Sigma 18-35mm F1.8 DC HSM Review: Digital Photography Review

Studio Tests

The Sigma 18-35mm F1.8 DC HSM turns in an exceptional performance in our studio tests, in essence matching a selection of high quality primes. It's remarkably sharp, even wide open, and both chromatic aberration and vignetting are relatively low. Distortion is kept pretty well under control too. Overall this is very, very impressive indeed.

Sharpness	The 18-35mm is remarkably sharp even wide open at F1.8, and in the wider half of its range (18-24mm), there's no measurable increase on stopping down (i.e. the lens is effectively diffraction limited). At the longer end (28-35mm) there's a slight improvement in sharpness on stopping down to F4, but in practice it's unlikely to be especially noticeable. For an F1.8 zoom, this is little short of astonishing.
Chromatic Aberration	Lateral chromatic aberration is pretty low. The graphs indicate a little green/magenta fringing at wideangle, and moderately strong blue/yellow fringing in the middle of the range (note though that this tends to be visually less intrusive). At the long end, chromatic aberration is essentially nonexistent.
Vignetting	Vignetting is remarkably low for such a fast lens, reaching just 1.3 stops wide open at all focal lengths. It also essentially disappears by F2.8. Overall it's unlikely ever to be problematic in real-world use.
Distortion	Distortion is kept reasonably well under control - it certainly doesn't exceed what we'd expect for this kind of lens. There's visible barrel distortion at wideangle, turning to pincushion distortion at the long end, but no more than you'd get from any other premium standard zoom.

Lens test data compared

To get a bit more perspective on just how good the 18-35mm is, let's compare it to a couple of benchmark lenses, using the comparison tool in our lens data widget. Click on the images below to open side-by-side comparisons in a new window or tab.

Compared to Sigma 35mm F1.4 DG HSM

The Sigma 35mm F1.4 DG HSM impressed us hugely when we reviewed it at the end of last year, and is probably the sharpest 35mm F1.4 prime on the market. When tested on the same camera, the zoom may be just fractionally less sharp at large apertures, but you probably wouldn't see any difference in real world shooting. The zoom also has slightly higher vignetting and distortion, but lower chromatic aberration. From this data, you'd be hard pushed to see any meaningful differences between the two in side-by-side shooting. Remember this is the 18-35mm's weakest focal length.

Compared to Tamron 24-70mm F2.8 Di VC USD

The Tamron 24-70mm F2.8 Di VC USD is probably the best value fast 'normal' zoom for full frame cameras, and like the Sigma 35mm F1.4, we had no hesitation in awarding it a Gold Award in our recent review. Not only does it offer built-in image stabilization, optically it comes as near as makes no difference to its Canon and Nikon counterparts, which are both much more expensive.

These lenses can be compared in several different ways, but its clear that regardless of whether we look at them them both tested on the same camera body, or at how the Sigma on APS-C compares to the Tamron on full frame, the 18-35mm easily holds its own in these studio tests.

Compared to Canon EF-S 17-55mm f/2.8 IS USM

Canon's EF-S 17-55mm f/2.8 IS USM is a highly regarded fast normal zoom for APS-C SLRs, and in comparison to the Sigma, offers an extended zoom range and built-in image stabilization, which makes it a very flexible lens indeed. But when we compare the two purely in terms of image quality, it's clear that not only is the Sigma noticeably sharper than the Canon when both are set to F2.8, it's actually sharper at F1.8 than the Canon is at F2.8. In all other respects, it matches up well too.

GearShop

Sigma 18-35mm F1.8 DC HSM Lens (Canon EF Mount)●	$799.00	Buy on GearShop
Sigma 18-35mm F1.8 DC HSM Lens (Nikon F Mount)●	$799.00	Buy on GearShop
Sigma 18-35mm F1.8 DC HSM Lens (Sony A Mount)●	$799.00	Buy on GearShop

Sigma 210101 18-35mm F1.8 DC HSM Lens for Canon APS-C DSLRs (Black)	$795.00
Sigma 210101 18-35mm F1.8 DC HSM Lens for Canon APS-C DSLRs (Black)	$795.00
Sigma 210306 18-35mm F1.8 DC HSM Lens for Nikon APS-C DSLRs (Black)	$799.00
Sigma 210109 18-35mm Lens for F1.8 DC HSM for APS-C sized sensors (Black)	$768.65
Sigma 30mm f/1.4 DC HSM Lens for Canon Digital SLR Cameras (Black)	$455.95
Sigma 210110 18-35mm Lens for F1.8 DC HSM for APS-C sized sensors (Black)	$774.49
Sigma 878101 USB Dock Lens Firmware for Canon Lenses (Black)	$59.00
Sigma AF 18-35MM F/1.8 DC HSM Lens Kit for Pentax	$799.00
Sigma 884306 17-70mm F2.8-4 DC Macro OS HSM Lens	$384.45
Sigma 30mm f/1.4 EX DC HSM Lens for Canon Digital SLR Cameras	$469.00
Sigma 30mm f/1.4 EX DC HSM Lens for Nikon Digital SLR Cameras	$309.95

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Comments

Total comments: 275

Will this lens work on my Canon Rebel T1i?

0 upvotes

Yes

0 upvotes

Hi Pros, this can be a good match to canon 6D? Im planning to buy 24-70mm tamron lens but its costly

0 upvotes

The lens is designed for use on APS-C cameras, not full frame like the EOS 6D. This is covered on page 4 of this review.

1 upvote

Yeah, just get some ideas from the Professional like you, so any suggestion for all around lens to my 6D except 24-70mm of canon & tamron they are costly.. what about the kit 24-105 but it was an old model. thanks for your reply Andy, hope you can help me to have a usable lens which is not soooo expensive : )

0 upvotes

I have the 24-105 f4 L for my 5D and it is a good lens. Yes the 24-70 2.8 will be a bit brighter and probably a bit sharper but as a general lens for Canon FF I have been very happy.

1 upvote

thank you guys, so I have to save money to buy canon 24-70 2.8 till next time..

0 upvotes

Put this baby on the new Canon 70D and see if there are any autofocusing issues. The two are a match made in video heaven.

0 upvotes

I have the 70d and had the sigma 1.8 18-35 but returned it yesterday because the auto focus was horrible. I thought I had a defective unit, but after reading the updated review, maybe not. Admittedly I was trying to test focus using the viewfinder, and maybe it might be better in liveview, but frankly taking photos in live view isn't that great on the 70d because of the slow recycle times. I also don't have the USB disk so maybe that may have helped, but out of the box, anyway, it was unusable for me. In retrospect, I wish I played with the micro adjustment a bit more, but compared with the kit 18-135 lens, it was so bad I thought it must be defective.

2 upvotes

Went out shooting like any other day with my 70D and the auto focus missed too often. I never shot below 1/125 sec. The colour and contrast was very nice and when it hit, the images were beautiful. What's the point of having f/1.8 if the hit rate for keepers is so low. I returned mine as well. After reading this review, I was reluctant to try another copy. Too bad, I really wanted to like this lens.

0 upvotes

I don't understand why sigma wouldn't calibrate the lenses better at the factory. Instead they offer a separate dock to calibrate it stand alone (without camera body) so that it can focus properly. I don't get it, do they expect that most people that buy this lens would buy a separate appliance to do something that should be done before it ships out? I had really high expectations for this lens based on all the previews. Maybe I'll give it another shot in the future if the problem is fixed, but for now, it sucks being the guinea pig.

1 upvote

I'd have liked to see it on a D7100, to see if the better AF on the Nikon would have helped its performance. I'd hate to have a good lens that is inconsistent re AF. Other relevant issu is flare, my Sigma (17-50mm f/2.8) is not that good in that respect, this one looks a bit better (but flare is ugly when it shows, with that greenish tint that is the same as in my Sigma).

0 upvotes

Excuse me for sounding dense, but isn't autofocus a function of the camera? How can you blame a lens for the shortcomings of the cameras autofocus system inability to lock on to the proper focus point? Also wouldn't a 51 point focus system behave differently than the camera AF you just tested?

1 upvote

AF has to be a lens issue in the first place.
why we need AF lens,
fast AF lens,
quiet AF lens,
smooth AF lens, and
accurate AF lens, etc.

Comment edited 3 times, last edit 3 minutes after posting

1 upvote

@ yabokkie,
I think your comment is inappropriate and show an incredible incomprehension of how works a digital camera. Perhaps you should learn how it works before adding comment that do not add any value to a post.

2 upvotes

No, it's not only a body issue. AF uses camera-lens comm and lots of calculations. I have tested carefully the Sigma 17-50mm f/2.8 and compared it to the Nikkor 35mm f/2, and the Nikkor performs much better re AF consistency and accuracy compared to the Sigma.

0 upvotes

@Eric Ouellet,
just ask yourself why we should ever need an AF lens which may be a good starting point and read something about the EOS system and EF lens design (AF changed the way we design lenses and it's still one of the major factors behind new lens designs).

0 upvotes

I've used this lens for a wedding and have to say that I really do not agree with the micro focussing comments in the review. It is a superb lens with amazing optical quality, a very usable f1.8 at all focal lengths, and spot-on focus in all light levels and for a wide variety of contrast levels. Out of 800 images I only had a handful that were blurred or soft focused. Maybe I've got a good one and the reviewer had a bad one, but from my own real world use it is a stunning lens!

0 upvotes

How is it re flare? The DPR tests says it's good, but that's my main problem with the otherwise very good Sigma 17-50 f/2.8 on the D7000. Even a sideways brigh window may cause ugly greenish flare that is absent when I use even the cheapest kit lenses.

0 upvotes

I will certainly consider this lens when there are rapports that the autofocus has been fixed and is consistent.
The test site SLRgear also noted this in their review:
http://slrgear.com/reviews/showproduct.php?product=1609

0 upvotes

Ordered mine this morning. Very excited to put it on the C100 - it will compliment my 24-105 and 70-200 perfectly.
I wasn't a huge fan of the Tokina 11-16 like everyone else - a bit too wide for shooting talent inside - as I do often, and the 24-105 isn't wide enough most of the time for me.
Sold the Sigma 30mm 1.4 as soon as I placed the order for this lens.

0 upvotes

Given the large size of this honker, I'd rather carry my smallish FF camera (Sony a850) and a conventional lens. Might as well be a prime, with this scant zoom range. Still, it's an achievement that it's as sharp as it is.

1 upvote

How much does a smallish FF camera (Sony a850) and a conventional lens cost and weigh compared to this lens and a crop camera.

0 upvotes

A lovely lens if you use that focal range. However, the argument for it over a 35mm prime is unconvincing for me. You always have to compromise on focal range if you want a large aperture and quality results. This particular compromise may suit more people than they realise. Try doing a careful analysis of the focal lengths you used in you 'best' what? 50 shots? I did this and realised that for 85% of what I do I could use a 35mm, so for a little flexibility this zoom will be fine. Or I can save money, get sharper glass, 1 more stop and walk a few yards forwards or backwards (oh, and save a few grammes to boot).

1 upvote

the image circle is tight but you can use it as a 35/1.8 on 35mm format.

0 upvotes

This lens is like three primes: 18, 24, 35 mm. Or in case you can live with large gaps: 18 & 35 mm primes.

I shoot with 35 mm prime most of my time and I am considering buying now a lens in the 18 mm range. So this one lens can replace 2 ... 3 primes.

1 upvote

Excellent review! My Sigma 30mm F1.4 also has very inconsistent focussing abilities, wide open it constantly misses the focus point..

0 upvotes

I don't have the issue maybe it's because different environment or handling but maybe that's why Sigma invented the USB dock.

just like Canon invented a great mount that all the modern mounts follow because they had so many troubles with their crappy mounts before.

0 upvotes

High praise indeed and long may it continue for innovation's sake.
My next prime lens (macro) decision would certainly involve considering Sigma.

This also brings to mind what I have said long ago. Optical View Finders are dinosaur/submarine/WWI tech. That is why the focus is impossible to ascertain in the viewfinder.

EVFs are the only way to go. They are so good nowadays, they even offer focus peaking which would allow the photographer to see the point/areas of focus. Its an essential feature which any photographer needs (if only they ditch the OVF).

6 upvotes

Your view on viewfinders is almost laughable. Why the hell would some of us even want EVF, it is terrible on battery life and most important of all it is more annoying to use than a standard viewfinder. Many photographers still use film and they wouldn't dare replace the viewfinder. I think you should try using a camera more than commenting trash mate.

Comment edited 2 times, last edit 55 seconds after posting

4 upvotes

Wow, Hetty. Preternatural Stuff's comment is far from trash. OVFs are archaic technology. EVFs offer far more advantages than OVFs. New DSLRs today offer live view purely for the reasons why people love EVFs. I figure you trust your camera's metering to rely on proper exposure, huh. Focus peaking on a manual lens is a godsend. Mirrorless tech and EVFs are the future.

4 upvotes

One thing that people forget about is that when using an OVF you look THROUGH the viewfinder, with an EVF you look AT the viewfinder.

The OVF is much easier on the eyes. If you have ever had to shoot a 10 hour sporting event you'd be really miserable with eye fatigue at the end of the day with an EVF.

Comment edited 27 seconds after posting

3 upvotes

Sigma knew about this in an interview. For newer, high resolution systems, contrast detect is the way to go to for their future high quality lenses. It must have been the reason, they went the trouble to create and give a USB dock.

3 upvotes

The cynical reason to release the USB dock is that they can skimp on quality control and pass some suboptimal lenses, then have the user pay extra for said USB dock and to top it off have the user spend their own time to actually make the lens behave as it should have out of the box...

1 upvote

Cons: "Physically rather large for a standard zoom" ... well, geeez loueeeze, whattay expect for a constant 1.8 zoom :(

4 upvotes

simple comarison in weight:
- Sigma 18-35/1.8, 810g
- Sigma 24-70/2.8, 790g
- Tamron 24-70/2.8, 825g
- Canon 24-70/2.8L2, 805g
- Nikon 24-70/2.8, 900g

quite similar weight for a narrower zoom range but relatively longer back focus to overcome.

1 upvote

It's a valid point though. It simply IS large which is a consideration.
If you were to go landscaping and you have to choose between this and your standard 18-70 at half the weight and size, knowing you will not go below f/8, the size is objectively a con.

The f/1.8 OTOH is clearly listed at the plus side, so DPR are consistent.

1 upvote

the size, weight, and price are all in line with existing lenses beautifully except the performance for an APS-C SLR lens.

Comment edited 2 times, last edit 2 minutes after posting

0 upvotes

What the heck? Why are third-party lenses tested on the smallest available sensor with which they are compatible? Test it on a 1.5x crop APS-C sensor and make your results valid to a wider audience.

3 upvotes

We have data for plenty of lenses on both 1.5x and 1.6x crops, and the difference between them is utterly insignificant in terms of assessing how well a lens performs.

2 upvotes

the difference is just under 5%.
the limit that we tolerate (or we used to tolerate?)

0 upvotes

Who is "we" in your statement?

1 upvote

@KerryBE: 'We' in this statement refers to this very website, dpreview.com: I write all the lens reviews here. Here's a comparison between the Sigma 17-70mm F2.8-4 DC OS Macro HSM |C on Canon and Nikon cameras. The slight difference between sensor sizes has little impact on the lens measurements.

Comment edited 2 minutes after posting

0 upvotes

Thank you. I was wondering who @yabokkie viewed as "we". Is he/she on your staff?

0 upvotes

I think the problem is that sensor resolution has outpaced autofocus system accuracy. I noticed this with the previous generation of cameras as well. If you don't focus with live view on its highest magnification the camera is not going to focus on the exact point you want it to and the shot will look off. Maybe Hasselblad is going the right direction by sticking to a single focus point.

3 upvotes

I agree that with current high resolution of sensors and current high resolving lenses at large aperture focus becomes very critical indeed.

That being said, I now have a company which I can move the AF point over quite a large area. It does so swiftly and the AF is always spot on ( low light, wide open, high res). So after I say this can be done, you could never sell me single AF again.

0 upvotes

I think DPR is being really unfair on the focus issue about this lens.

This Canon 19-point AF module(used in 7D and 70D) is not really known for its extreme accuracy. The same can be said for the rest of the Canon APS-C AF modules. Lensrentals did a excellent test on Canon bodies, and it can be read here:
http://www.lensrentals.com/blog/2012/08/autofocus-reality-part-3b-canon-cameras
In the test, they are using the 28mm f/2.8 IS, which is less demanding then this sigma, and still get very inconsistent AF results.

I highly suggest DPR do the same AF "evaluation" with a fast prime on the same body and tell us how consistent the result is. I suspect that those fast primes are so soft at F1.8 that it's hard tell slight focus consistency.

The reality is that current PDAF sensors simply does not have resolution to satisfy ever higher pixel count main sensor. With CDAF, this lens will be sensational.

Comment edited 2 times, last edit 3 minutes after posting

10 upvotes

I can confirm your observation about general AF precision on Canon APS-C bodies. I have had a 7D for more than three years now. While I like the camera overall, I never fully understood all the buzz about its purportedly great AF module. It has let me down more often than not with inconsistent focusing.

About the Sigma 18-35: I recently orderered one. My first tests didn't show any more inconsistent focusing than I am used to from my 7D. However, depending on focal length and subject distance, the AF was either OK or (consistently!) off (always frontfocus, sometimes needing around +20 microadjust). Sounds like a case for the USB dock, but it was so bad that I decided to not take any chance, I think my copy was defective. Since I liked everything else about the lens (IQ, speed, built), I opted for a replacement, which I am now waiting for.
BTW: I tried the Sigma on three different bodies, my 7D and 450D, and a colleagues 60D, focus deviation was more or less the same on all of them

5 upvotes

I don't think DPR are being unfair. They found this issue, went in-depth to find if they could resolve it, and reported back with what they found.

In the end they scored the lens 86%, gave a glowing review and a Gold Award, and padded the focus issue with several clear YMMV statements.

I think that is exactly what could be expected of them, but many peeps here seem to have only read the critical part of the review.

3 upvotes

I don't know how others tested but 7D's AF module is quite conservative that it covers only a small area at center for better accuracy, and the accuracy is good (though I strongly prefer 51-point Nikon which covers much large area on APS-C).

Comment edited 18 seconds after posting

0 upvotes

The autofocus problems - is it Sigma or is it Canon? You really should make a followup with other bodies.

4 upvotes

Question: Do all F/1.8 lenses have this "focus" issue, or just the Sigma 18-35mm? Or are we mistakenly blaming the Sigma for what might really be a body PDAF issue? What if the PDAF is tuned for an F/2.8 light cone? Then the AF tolerances might be fine for the 24-70 F/2.8 but not an F/1.8 lens?

2 upvotes

From my experience, usually large aperture prime lens like the Zeiss 85mm f/1.4 or even the Canon 85mm f/1.2L MkII has focus shift issues. As long as one understand it and know how to adjust accordingly, its OK. The focus shift normally will occur when one try to focus at close distance at the wide open aperture.

This problem seldom occur on f/1.8 lenses like the Canon 85mm f/1.8.

So far, no other brand except Sigma has made an 18-35mm f/1.8. As such, it is difficult to compare.

Other possibilities could be poor quality control and "not so compatible third party firmware" Remember, this is a third party lens after all. Sigma does it by reverse enginneering.

Comment edited 2 times, last edit 15 minutes after posting

1 upvote

I'm pretty sure if Sigma made an 18-300 f/0.95 lens that was 3 inches long was built out of unobtanium, weighed 3 grams, nailed focus on every shot, was sharp at all focal lengths across the frame and cost $35, that 75% of the people here would STILL find something to complain about.

5 upvotes

Can I preorder that lens, please?
I won't complain, I promise!

3 upvotes

Wide angle is not wide enough! Bad lens! =)))

3 upvotes

Amen ...

0 upvotes

Too bad this lens has inconsistent focus issues.

0 upvotes

I'd buy this lens for indoors pictures of my kids. I need a wide and fast lens. My ideal lens would be a prime 18-20mm F2. But this zoom is also appealing. Sadly, the pictures in your gallery are not very relevant for my interests. So, can you guys go into a pub, in the evening, and take some pics of the people there? Please! I might even pay for a pint! No flash - just the indoor lights!

Comment edited 37 seconds after posting

1 upvote

I don't have pub pictures, but these were taken in very poor lighting in a closed of city Street. Hope it helps:

http://www.reddit.com/r/photography/comments/1lksqe/need_the_speed_sigma_1835mm_f18_dc_hsm_indepth/cc0y5db

3 upvotes

Thanks!

0 upvotes

Why those micro focus adjustment are necessary and would it be true for the new Canon EOS 70D also ?
The focus adjustment should be necessary on any lenses because it is the camera who read its and tell the objective to focus nearer or further.
How this could only affect this lenses ? Is this only a question of incompatibility between brands or could it be corrected by a firmware update ?

2 upvotes

I have the impression that you penalize the lens for a problem of the camera body itself (focus evaluation) ???

3 upvotes

It seemed a bit strange that in the DXO test article not a single Nikkor lens was included in the extensive list of comparison lenses.

1 upvote

DxOMark's article is titled "Sigma 18-35mm F1.8 DC HSM A Canon mount lens review", which might explain the lack of Nikkor comparisons. Expect those to show up when DxOMark gets a Nikon mount version to test.

Comment edited 2 minutes after posting

7 upvotes

I think DXO also kind of borked their test of the Nikkor 17-55. Their perceptual resolution shows the 17-55 at only 6MP on the D7000, a performance that would leave it well short of 35mm film and no better on the D7000 than on the D200 which has very heavy anti-aliasing and 40 percent less resolution. I can tell you that isn't the case at all. I suppose there was something wrong with DXO's test — perhaps a D7000 AF system out of adjustment or something like that. I can only say that my own experience of the 17-55 leaves me very curious to see how it would perform with a D7100 — in other words, it's in the ballpark with the Sigma.

The other question, of course, is focusing accuracy out of the lab. f1.8 gets into some pretty demanding territory on the AF system so I'll be interested to hear how that pans out for people. The combination of the 17-55 and most Nikon bodies is finicky enough already; the AF on the body has to be PERFECTLY in adjustment to run that lens reliably.

2 upvotes

DxOMark's lens testing doesn't rely on autofocus, but uses manual focus instead, carefully checked to ensure that the lens is optimally focused.

A far more likely reason for getting disappointingly low sharpness data would be that they may have tested a 'bad copy' of the lens.

2 upvotes

we are all human but I don't think people at DxOMark are stupid enough to use AF in their tests. MF on live view should be the standard for many years. only the sharpest shots will get processed and the highest number used.

btw, I only see bad copies of DX17-55/2.8, a good example of "good build, no good glass."

Comment edited 3 minutes after posting

3 upvotes

I agree with Daniel that the DxOMark test of the 17-55 Nikkor seems flawed to say the least. I owned the 17-55 f/2.8 a number of years ago pre-D7000 days, but remember it being bitingly sharp lens with extremely good color/contrast typically found in higher grade Nikkors.

Note that 17-55 f/2.8 performed extremely well in the Photozone and Lenstip resolution tests.

1 upvote

These comments have made me realise that lots of people don't understand what the 'standard' in standard zoom means....

5 upvotes

it could mean different things and can be made clear with one word, standard aperture/grade or zoom range.

no problem unless some one call standard super high grade.

Comment edited 3 times, last edit 2 minutes after posting

0 upvotes

A "standard zoom" traditionally goes from wide-to-short telephoto like the classic 24-70 f/2.8 FF zooms. The APS-C equivalents are the 17-50 or 17-55 f/2.8 lenses.

The Sigma 18-35 f/1.8 only goes from wide-to-normal (27-50 on Nikon/Sony, or 29-56 on Canon) and therein lies the confusion.

Since it lacks the telephoto focal lengths it would seem to be a more specialized, slightly less versatile lens than a traditional standard zoom.

Comment edited 1 minute after posting

2 upvotes

This is crap. Who can define a standard zoom? For that, we need first to fix that standard. If you look at other manufactureres, a fast Zoom with such an aperture is always short in range, the Nikon 17-35/2.8 for example, the Tokina 11-16/2.8 is another one. The faster a zoom gets, the shorter the range. Doing a zoom of a displacement of more than 20 mm with such an aperture is a challenge, and imagine the size you need to do this.

So, if Sigma brings us a 18-35 with 1.8, one can only say, "hats off" it's a performance. Now, if they did a 18-55/1.8, it would be the size of 300/2.8 barrel, and I doubt that anyone would buy it. My only concern is that it is somewhat expensive, but, i will not buy it anyway, I prefer to invest that money in a huge prime with 1.8 or 1.4 aperture.

0 upvotes

it used to be 35-70mm before but makers have been pushing it wide and wider to 28-70 and 24-70 now.

18-35/1.8 is about 28-54/2.8 equiv. so only thing we may complain is the narrower range which makes it more "standard" than standard 24-70/2.8 ones.

2 upvotes

@Shamael

"the Nikon 17-35/2.8 for example, the Tokina 11-16/2.8 is another one."

But that's my point - those aren't standard zooms. They're both wide zooms - the first for Full Frame, the latter for APS-C.

1 upvote

hey, would "a premium aperture standard-range lens with standard wide-end and a bit shorter-than-standard tele-end" designation do? :)

0 upvotes

Can
"Physically rather large for a standard zoom"

And whats standard about a f1.8 18-35mm lens.

Nice review and a very impressive achievement by sigma. Shame the likes of Canon can't innovate on anything less than £10,000

4 upvotes

f/2.8 zooms for 35mm format are good reference.

Sigma 24-70/2.8 is sold for less than half of C/N so price is not a special issue for this lens.

0 upvotes

Just to tidy up the unexpected controversy over my use of the term 'standard zoom' - this is traditionally used for a zoom that covers the 'normal' focal length range (~28-35mm on APS-C), and so might plausibly used 'as standard' for everyday shooting. The 18-35mm fits within this category.

4 upvotes

When is controversy ever unexpected on this site?

1 upvote

From the Lenstip review: "accuracy of the autofocus, our assessment is very positive". Any AF errors were less than 4%.

Note they tested it on a Canon 50D.

The Lenstip Con list for the Sigma 18-35 is appropriately short.

Any large aperture lens shot wide open, especially handheld will give occasional focus errors.

The Gold Award is cool but DPR's rather long list of "Cons" for this ground-breaking lens is unfortunate as Sigma truly deserves nothing but Kudos for.

5 upvotes

The lens's AF accuracy is great if you sit in a studio and point it at high contrast, well-lit test charts. Much less so if you go out and actually take photos with it in the real world. Personally I think photographers should be more interested in the latter. YMMV.

7 upvotes

Valid point Andy. Lenses do need to be tested under lots of different types of lighting otherwise problems like the one you discovered are well... not discovered. As soon as you test two or more lenses that show the same issue then it starts to turn into a major issue.

1 upvote

No my mileage is pretty much the same. The point is your review even talks about focus errors "wide-open" in "less than ideal conditions". But judging by the comments, the big takeaway from this review is that the 18-35 has an AF problem.

ALL lenses shot wide open in low-light have a lower accuracy hit rate related to the thin plane of focus. This "problem" is even greater on FF.

3 upvotes

@marike6: "ALL lenses shot wide open in low-light have a lower accuracy hit rate related to the thin plane of focus."

Obviously I know that full well (chances are I've shot with more different lenses and systems than almost anyone commenting here), but in my judgement the 18-35mm has an unusually high misfocusing rate when shot wide open in real-world use. This is corroborated by my colleagues who've also used the lens. The limited depth of field is not all that there is to it here - it misfocuses more often, and more obviously, than a Canon EOS 6D + 24-70mm F2.8 shot side-by-side at F2.8.

6 upvotes

Relevance of AF accuracy in bad light

I frequently shoot with 35mm f/2 wide open. And I actually do shoot wide open more in less than ideal lighting, because then you need to. So AF in real life in low light to be accurate is important, as it would be a popular shooting condition for people who would buy such a lens.

Is repeatedly accurate focus in low light 35 mm f/2 in real world even possible?

Until a few months ago, I would have set no. With cameras I shot in the last decade I could not accomplish it. With my own dated DSLR AF was so bad wide open that I always focused manually with split screen. Works 100% with tripod and fixed target. In real life everything moves and I lived for a decade with more misses than hits.

Then I got a new camera and suddenly pretty much all my pictures are accurately focused. Bad light, wide open and moving subjects.

I was stunned. Now I would not accept less with new equipment at this price level. I guess that is what Andy is saying.

2 upvotes

How the heck can you have limited zoom range as a "con"? If you buy a 18-35mm, then that is what you get.
If you buy a 16mm prime, you cant say that it is a negative that it is too wide. It is what it is!

15 upvotes

The lens doesn't exist in isolation. If you compare to other standard zooms that you might buy to put on your camera for everyday use - a 17-50mm F2.8, for instance - it has limited zoom range. If you go out and shoot with it, the limited compositional flexibility this imposes really is quite obvious.

The list of 'Cons' is simply things we find users may need to consider when making a purchasing decision. The whole idea is that you can look at them and decide whether they matter you to you. If not - no problem.

9 upvotes

But the 18-35 is not a Standard zoom, and there aren't ANY standard zooms with f/1.8 max apertures.

2 upvotes

18-35/1.8 is a standard f/2.8 equiv. zoom for APS-C SLR. Sigma did a great job that it's much better than small aperture 17-55/2.8 zooms from Nikon and Canon.

what's great is not the aperture, but a high quality wide-standard angle zoom for APS-S SLR which is the most difficult mount (that happened to become popular for some technical reasons we had more than a decade ago).

Comment edited 3 minutes after posting

0 upvotes

Would you ever go and buy a 18-35mm zoom? Probably not. Unless it's a 1.8 throughout the whole range and has some superb optical performance - which makes one wish it stretched a bit further to perhaps 50mm, no? As much as I'd love to have this lens, the limited zoom range is a dealbreaker for me.

2 upvotes

Good job in the AF tests IMO. Thanks

2 upvotes

Any still labouring under the illusion you can still use film camera lens circles of confusion as guides to the acceptable focus errors of a lens? Sorry, that ended around the 4-5 megapixel mark, perhaps even less than that. Cameras now are capable of such high resolution that any focus discrepancy is visible.

0 upvotes

E-mount please!

3 upvotes

You kind of get this already with the alpha mount and an adapter, don't you? It's still a PDAF optimized lens. It's also near as 2 lbs. Buy an SLT to stick it on, sheesh.

Comment edited 41 seconds after posting

0 upvotes

this is the greatest lens that I had been expecting and it came with better quality than expected, but I decided not get it for it doesn't add value for me. would be a no-brainer before 5D, good before 5D2.

still, great job and go ahead (f/1.8 zooms for APS-C mirrorless, too, and f/1.4 zooms for 4/3").

Comment edited 4 minutes after posting

0 upvotes

Wow, this "AF issue" is being blown completely out of proportion. I've had this lens for over a month now and haven't had even the slightest indication that there is anything wrong with the AF. If there is any inconsistency I'd say it is well within the limits of what is normal for any lens using phase-detect focus.

And since the open-loop AF myth has been de-bunked (i.e. PDAF *does* confirm focus after shifting) then a large part (all?) of any inconsistency will be the fault of the AF sensor.

6 upvotes

You are quite right. According to "lenstip.com" in their reveiw which is much earlier than DPR, they have not notice any problem with AF except a little at 18mm.

However, they have encountered flares to occur in their test.

Overall, they have a very possitive conclusion.

So, we do not know how DPR reached their conclusion.

Now, we have to wait for "photozone.de" for their review and conclusion.

4 upvotes

In fact, none of the previous reviews I have read have mentioned any AF issues.

2 upvotes

We reached our conclusion in much the same way as usual - by shooting hundreds of real-world shots across a range of subjects and under different lighting conditions, using Canon bodies from the EOS 7D to the EOS 100D. As explained in the text, we looked at AF microadjustment (both in-body and via the USB Dock), which improved AF accuracy but didn't fix the shot-to-shot consistency we saw. Finally we got hold of a second copy of the lens to see if it showed the same symptoms which it did. Then the three of us who'd used the lens that most (all highly experienced SLR users) discussed it and decided the 18-35mm's focusing inconsistency was beyond what we'd usually expect.

I'm not sure what more we could do.

Comment edited 2 minutes after posting

8 upvotes

@Andy Westelake:

What about trying a sample for another mount, like for Nikon?
I have owned a Sigma EX 18-50/2,8 for Canon, exhibiting quite "outspoken" AF-issues. Friends have owned Nikon and Sigma w no trouble at all. Actually, I have seldom heard of such issues with Sigma in Nikon or other non-Canon mounts. Surely there have been such issues, but I have a distinct gut feeling that Canon is the mount Sigma have had most trouble with, historically and possibly even today.

Comment edited 2 minutes after posting

3 upvotes

Thanks for the details. I'd really like to see this tested by Lensrentals.com too with a comparison vs a few other lenses. I just find it a little strange that this hasn't been noted anywhere else, and I believe I've read/watched pretty much every review out there.

Obviously, having bought this lens I know my view is probably biased, but I'm really trying to look at this issue objectively.

Btw, did you notice if the AF inconsistency was any different at 18 vs 35mm?

2 upvotes

@revio - we can't try the Nikon mount version, as it's not yet available.

@David Naylor - my personal impression (which I haven't systematically tested) is that AF inconsistency is a little worse at 18mm compared to 35mm, but no focal length is immune. For the record, the lens also focused more accurately and consistently in live view than when using the OVF.

Comment edited 44 seconds after posting

1 upvote

Very informative review Andy. Thanks for your efforts.

While I've had the 18-35 for less than a week and have had limited opportunity to use it, I have to agree with David Naylor about the AF. I have not had any concerns with it thus far. I was surprised to find it was a concern in the review.

By way of contrast, my 50mmf1.8 is totally untrustworthy re: AF. I do not feel that way about the Sigma f18-35. Yes I know, apples and oranges. I'm just trying to give my sense of the magnitude of the problem: I don't doubt that the reviewers have identified a legitimate issue, but I simply haven't found it to be a limiting factor thus far. It certainly is a limiting factor with my nifty-fifty.

1 upvote

quote from the review
"... when focusing manually with most Nikon SLRs you have to remember to set the aperture to F1.8 before entering live view, as they're incapable of adjusting the lens's diaphragm during viewing."

Definitely not true for Nikon cameras and lenses in general. Just tried it with my D800 and 85/1.4 and it works just fine adjusting the aperture in live view. It even works with old mechanical link aperture lenses (like the AF DC Nikkor 105/2)

Maybe it doesn't work with Sigma lenses, but that is then their incompatibility.

2 upvotes

"they're incapable of adjusting the lens's diaphragm during viewing."

Yes, 3rd party lenses sometimes forget a few nuts and bolts, here and there. but hey... that's what makes 3rd party lenses exciting!

The GOTCHA!

1 upvote

@Octane - your D800 is, along with the D4 and D3 series, one of the few exceptions to the rule (which is why the text said 'most'). Of course these are all full frame cameras, and unlikely to be used with the 18-35mm. All of Nikon DX format SLRs show this rather unexpected behaviour in live view, where changing the aperture setting doesn't adjust the diaphragm. I've modified the text to make this more clear.

@CameraLabTester - this isn't anything to do with 3rd party lenses, but is inherent to Nikon's implementation of live view in all but its most expensive SLRs.

Comment edited 4 minutes after posting

7 upvotes

AF inconsistencies for the different focal lengths across a zoom lens aren't too uncommon, which is why Canon started including the ability to set independent AF adjust values for either end of a zoom lens, with the firmware interpolating between the two for the intermediate focal lengths. The 70D is Canon's first APS-C body that supports this zoom dual-AF adjust facility; it would be interesting to see if that sufficiently resolves the AF inconsistency problem you observed. Perhaps you can revisit this when you have a 70D on hand?

0 upvotes

As we explained in the review, Sigma's USB Dock and Optimisation Pro software allows more detailed AF microadjust setting (4 focal lengths x 4 distances) than any SLR body. Even so, while it improved AF accuracy, it didn't fix the inconsistency we saw.

The 70D, however, is quite likely to give the best possible focus accuracy and consistency, as well as speed, when using its Dual Pixel AF in live view.

Comment edited 18 seconds after posting

2 upvotes

Thanks Andy. I read the review but the conclusion is incorrect. That nature of a PDAF system limits the utility of a lens-based MA feature. It's actually much more effective to adjust in the body than in the lens. A PDAF acquisition involves multiple phase-detect sensing and lens movement cycles. Altering the magnitude of any single movement by the lens (lens-based MA) is an out-of-band correction for which the PDAF system will readjust for in the next sensing/movement cycle. In other words, it's an alteration that is lost in the feedback loop.

0 upvotes

I guess the main argument I'd use against this conclusion ('In other words, it's an alteration that is lost in the feedback loop') is that in-lens MA demonstrably works in practice, and can be set to give consistently accurate AF under favourable conditions. This was very obvious when I set microadjust up using the USB Dock and Optimisation Pro.

How might this work? Presumably, after using in-lens microadjust, the camera's AF system is happy that the lens is correctly focused after the initial focus movement, and doesn't readjust it again.

Overall, my experience is that armchair theory is all very well, but is no substitute for testing things out in practice.

1 upvote

Andy, the determination on when the PDAF system has achieved sufficient focus (within DOF marign) is based on the phase detection. The need for AF adjust occurs when the optical path through which phase detection is measured has a misalignment or lens aberration which affects the accuracy of the phase comparison. Focus-element positioning errors (mechanical errors) are self correcting via the multiple PD cycles. But those errors are detected/calibrated against the phase sensing mechanism, which has no self-calibration mechanism and thus requires AF adjust. It may seem like an armchair theory but it's based on my development of DotTune, which you can read about here: http://www.dpreview.com/forums/post/50774257 and here: http://www.dpreview.com/forums/post/50883023

0 upvotes

And again - Sigma's in-lens microadjustment demonstrably works in practice, and that really is all that matters.

Comment edited 2 minutes after posting

0 upvotes

Our discussion is whether in-body AF adjust works better than in-lens, and my assertion remains that in-body is better. I've experimented with Sigma's in-lens AF adjust on the 35mm Art (compared with in-body AF adjust) and my empirical results match the theoretical assertions. You say the Sigma's AF adjust works in practice yet you still report that its AF is inconsistent. Perhaps you're defining "work" as an improvement over the baseline, or perhaps as just observing a noticeable change in AF behavior. Going back to my original post I still believe the 70D's dual-AF adjust for zooms has a good chance of yielding more consistent AF results than what you observed using Sigma's adjustments.

0 upvotes

The Sigma's AF is inconsistent under less-than-ideal conditions. However, with a well-lit high-contrast target of the type used for measuring AF accuracy and determining microadjustments, it's much more consistent. Under these conditions, without in-lens AF microadjustments it's consistently (slightly) inaccurate, but with them it's consistently accurate. Therefore, in-lens AFMA works.

However, even after microadjust, the 18-35mm's AF remains inconsistent under less-ideal conditions on every camera we tested it on.

Comment edited 2 times, last edit 2 minutes after posting

0 upvotes

Thanks Andy. For reference, an AF adjust value that appears to be correct/accurate but is not can manifest as inconsistent shot-to-shot results, esp in marginal AF conditions. Can't say that's what's causing your issue but just wanted to mention it as a possibility. I have a post describing why here: http://www.dpreview.com/forums/post/50781856.

Also, was the lighting temperature for your low-light AF test the same as your abundant light tests?

Comment edited 2 minutes after posting

0 upvotes

I didn't do a low-light AF test. I went out and shot with the lens in real-world use, and that's where its AF inconsistencies became clear. Obviously, camera/lenses need to be able to focus under all types of light.

0 upvotes

This lens would be even more interesting on m4/3 giving you 36-70mm-e (moderate wide to moderate telephoto) at f/1.8.

4 upvotes

more interesting because of longer focal length? or
because m4/3" lenses are smaller aperture ones?

you will waste 0.6 stops mounting this on 4/3".

3 upvotes

More interesting because 36-70mm is a more practical working range. You have wide, normal, and telephoto, in one fast lens. On APS-C, it only covers wide and normal.

See the reviewers' conclusion that its "relatively narrow zoom range is undeniably a little restrictive."

I suspect they would not have made that comment if it were an m4/3 lens covering 36-70mm-e.

1 upvote

'you will waste 0.6 stops mounting this on 4/3".'

Sigma wasted 0.6 stops making it an APS-C lens.

2 upvotes

shameful that Canon cameras are resolution challenged but D7100 got 14.8MP within 4/3" range (it's 13.4MP for 70D).

it's much better to be able to do post-cropping for we can have better framing and less chance to clip-out wanted image when composing too tight or shooting fast moving subjects.

Comment edited 2 times, last edit 2 minutes after posting

0 upvotes

> Sigma wasted 0.6 stops making it an APS-C lens.

we deserve f/2.8 ones for 35mm format, so
we deserve f/1.8 zooms for APS-C, and
we deserve f/1.4 zooms for 4/3" not stopping at f/1.8.

Comment edited 2 times, last edit 1 minute after posting

0 upvotes

Both my Canon and Nikkor 50mm 1.4's are not consistent focusing in very low light. In fact most lenses are not that good focusing in low light. And none of them have microadjust.

My Sigma 50mm 1.4 and 85mm 1.4 are better performers in low light. Maybe it's also dependent on the body used?

1 upvote

i'm seriously interested in ... a 16-35 f1.8 for FF. :)

1 upvote

Great... but now please make a 16-35 version.
Yeah... people are never happy :p

2 upvotes

Focus issues? How about testing OEM lens in the same under less-than-ideal conditions? Are you kidding? White horse "miles" away with no contrast to focus at all at F1.4, seriously?
How about testing on Nikon instead of Canon? There are so many variables here that it is hard to believe this review.

3 upvotes

We can't test on Nikon because the F mount version of the lens isn't yet available. The example shown on the review is illustrative, but simply one of many which were misfocused at F1.8. If you'd been standing beside when I was shooting it (and I'm pretty sure you weren't), you'd know it wasn't 'miles away', but about 3m.

3 upvotes

For this lens even 3m is like miles away if you consider that the eye of the horse is so small and no contrast at all. Might as well focus on the white wall. Plus camera like 700D could easily be fooled to focus on the background with a lot of contrast. So if you have more misfocused examples but with better target we sure would love to see them. And also would love to see Canon 35mm F1.4 in this situation side by side.

Comment edited 2 minutes after posting

0 upvotes

Just use a split-prism DOH! This way you know exactly what you're focussing on. AF is over-rated.

0 upvotes

I just don't understand why any brand would sell a lens which needs tweaks for focus from the moment you buy it.
Looks like a FAB lens but as others have said, the focus issues suck.

0 upvotes

The way PD-AF as technology works is such that the precision needed to make a lens that always focuses perfectly well at max aperture like at F:1,8 is next to impossible to reach in mass pruduction like most lenses are the results of, so to speak.
Even if not mass produced it would still be next to impossible, simply because of the way such AF-systems are desiggned to work.
That´s why the need for "after manufacture adjustment" have come into existence, and why it is the chosen way of manufacturers to make their products more usable.

The constantly risen resolution (higher pixel count) of modern cameras made this necessary; had all cameras stopped at fex 6 megapixels these things (micro adjustment of AF) would not have came about.

Comment edited 3 minutes after posting

0 upvotes

This lens is not for me, not because I want a wide-ranging zoom, but because I want a long-ranging one. The 18-35mm range is just not one I use very much.

But if Sigma came out with a 35-70mm f/1.8 ASP-C companion to this lens, then I would WANT it.

4 upvotes

That would be great.

0 upvotes

I'd take both, and then a 70-210mm on top just to cover range I could possibly want. But 18mm at APS-C is a bit too narrow still, where's my 16mm-35mm eh?

1 upvote

For a given aperture the weight (and the cost!) of a lens increases basically with the third power of the focal length. So a 35-70mm f/1.8 lens would weight about 6.5kg and cost about $6400. Still interested? :-)

Comment edited 4 minutes after posting

2 upvotes

I'm not sure. The Olympus 35-100 F/2 costs around $2500 and weights a little over 1.5kg.

0 upvotes

If the cost and weight of a lens increases with the third power of the focal length, then this implies that there ought to be a big pile of good, cheap wide-angle lenses - that instead of "Nifty Thrifty 50s" there ought to be "Nifty Thrifty 15s". It implies that a Nikon 50mm f/1.8 prime should go for $600 - or even more for an FX version, given the 35mm f/1.8DX that goes for $200. It implies that either the Nikon 17-55 f/2.8 is way overpriced (especially for a DX lens), or the 24-70 f/2.8 is a serious bargain.

Something is wrong with this theory.

1 upvote

@kimchiflower
The Olympus 35-100 F/2 was designed for the 4/3format, so it covers an area much smaller than an scaled 18-30 for APS-C. The Olympus designers could use relatively small rear optical elements, mitigating somewhat the effect of the "third- power law". Consider also that if the Olympus lens aperture were F/1.8, instead of F/2, the weight and cost of the lens would be considerably higher. To get an idea of how the weight increases fast with the aperture, compare a 50/1.4 lens with a 50/1.2.

0 upvotes

@EKB
The "third power law" is a general trend, not an absolute law. If all the linear dimensions of a lens are scaled up by a factor k, the focal length increases by k, the f-number keeps constant, but the volume (and the mass) of the lens increases by k^3. In practice, this "law" is not so horrendous because the masses of the several parts are scaled only partially, or not at all, by the third power, as is the case of the mount. In general, the weight of the front optical elements tends to follow the third power law, but the diameters of the rear elements are related more to the sensor size than to the focal length, so the third power law applies only partially to the rear elements.

0 upvotes

@Frank_BR
In the 18mm to 70mm range, the general trend is so weak as to hardly be worth calling a trend at all. In fact, can you even name a single pair of Nikon F lenses of 70mm or shorter focal range that fit this third-power trend?

If I had to guess, I'd guess that a 35-70mm f/1.8 APS-C lens would be somewhat heavier and more expensive than the 18-35mm f/1.8. But not by a factor of 8. In fact I'd be suprised if it were more expensive by a factor of more than 2. On the other hand, I would *not* be suprised if a 35-70mm f/1.8 turned out not to weigh or cost *any* more than the 18-36mm f/1.8.

0 upvotes

Prime lenses for the FF format with focal length below 70mm can have very dissimilar design: retrofocus (35mm or lower), double-gauss (around 50mm) and telephoto (70mm or higher). Of course, direct scaling does not apply for different types of design.

You should compare lenses of similar designs, like the Nikkors 105/2.0 and the 200/2.0, for example. These lenses weight 640g and 2930g, respectively, with a ratio of 4.57. This value is below the "expected" 6.91 (1.9^3), but the discrepancy shouldn't be a big surprise because the weight of certain elements that made up the lens (mount, barrels, motors, etc.) does not follow the "third power law".

0 upvotes

"Prime lenses for the FF format with focal length below 70mm can have very dissimilar design."

Yes. Exactly so. And the same applies to zoom lenses and to lenses designed for the APS-C format that have focal lengths below 70mm.

"You should compare lenses of similar designs"

Why? Why should I expect a 35-70 f/1.8 to have a similar design to the 18-35 f/1.8?

In fact, I would expect it to have a different design - to *need* to have a different design - in much the same way that, e.g., the Nikon 24-70 f/2.8 has a different design than the 14-24 f/2.8

As it turns out, the 24-70 has about the same cost and weight as the 14-24 - in fact, it's a bit lighter (900 vs 1000g) and a bit less expensive. By analogy, I'd expect a 35-70 f/1.8 to have about the same cost and weight as the 18-35 f/1.8 - not eight times the cost and weight.

0 upvotes

"I'd expect a 35-70 f/1.8 to have about the same cost and weight as the 18-35 f/1.8 - not eight times the cost and weight".

I wouldn't be so optimistic. Consider first the Nikkor 24-70 F/2.8 lens that weighs 900g. Now consider a hypothetical 24-70 F/1.8 lens. The front elements of this lens would have a 2.5x larger frontal area compared to the 24-70 F/2.8. Usually, an F/1.8 lens has a much more complex design (more elements) and is physically longer than an F/2.8. What would be the weight of the hypothetical lens? Possibly more than 3kg, I guess.

In summary, with due respect to you opinion, I doubt it would be possible to design a 35-70 F/1.8 with the same weight of the Sigma 18-35 F/2.8.

0 upvotes

1. I'm not considering a hypothetical 24-70 f/1.8 lens, I'm considering a hypothetical 35-70 f/1.8 lens - and one that APS-C rather than FF, to boot.

2. By your logic here, the Sigma 18-35 f/1.8 couldn't possibly exist either:

Consider the Nikon 17-35 f/2.8 that weights 745g. Now consider a hypothetical 18-35mm f/1.8. The front elements of this lens would have a 2.5x larger frontal area compared to the 17-35 f/2.8. Usually, an f/1.8 lens has a much more complex design (more elements) and is physically longer than an f/2.8. What would be the weight of the hypothetical lens? Possibly more than 3kg, according to this logic.

3. Or to put it this way: The old Nikon 20-35 f/2.8 weighed 588g. The old Nikon 35-70 f/2.8 weighed 664g. The Sigma 18-35 f/1.8 weighs 811g. So a Sigma 35-70 f/1.8 should weigh what? Maybe 900-950g? Or maybe less, because the Nikon lacks the weight-adding 2mm at the wide end.

0 upvotes

"1. I'm not considering a hypothetical 24-70 f/1.8 lens, I'm considering a hypothetical 35-70 f/1.8 lens - and one that APS-C rather than FF, to boot."
-------------------------------------------------------

A hypothetical 35-70 F/1.8 lens for APS-C wouldn't be much lighter than a 24-70 F/1.8 lens, because in this case the overall weight would be given by the upper limit of the focal length, which is 70mm for both lenses.

"2. By your logic here, the Sigma 18-35 f/1.8 couldn't possibly exist either:
Consider the Nikon 17-35 f/2.8 that weighs 745g. Now consider a hypothetical 18-35mm f/1.8. The front elements of this lens would have a 2.5x larger frontal area compared to the 17-35 f/2.8. Usually, an f/1.8 lens has a much more complex design (more elements) and is physically longer than an f/2.8. What would be the weight of the hypothetical lens? Possibly more than 3kg, according to this logic. "
--------------------------------------------------------------------
to be continued…

0 upvotes

That was not a proper comparison! Even though those lenses have almost the same focal length, their angular coverages are very different for the wide angle end: 104º versus 73º. The difference of coverage makes a profound impact on the lens design. The Nikon is an ultra-wide- angle retrofocus zoom lens of very complex design, whereas the Sigma works in the relatively easy range of 73º to 43º. To have an idea of how difficult is to design a lens for a 104º angular coverage, please take a look at the Fig.29 (*) at:

https://dl.dropboxusercontent.com/u/60804047/British%20Journal%20of%20Photography%20-%20Feb.%201980.tif

Sadly the graph stops at 90º, but it is reasonably to conclude that a 104º angular coverage (Nikon) would demand 3 to 4 times more optical resources than 73º (Sigma).

(*) excerpt from "New Developments and Trends in Photography Optics at Zeiss", by Walter Wöltche, Head of Mathematics Department, Photo Optics Division, Carl Zeiss, Oberkochen

to be continued…

0 upvotes

"3. Or to put it this way: The old Nikon 20-35 f/2.8 weighed 588g. The old Nikon 35-70 f/2.8 weighed 664g. The Sigma 18-35 f/1.8 weighs 811g. So a Sigma 35-70 f/1.8 should weigh what? Maybe 900-950g? Or maybe less, because the Nikon lacks the weight-adding 2mm at the wide end."
-------------------------------------------------------------------------

The Nikon 20-35 F/2.8 lens is an ultra-wide-angle, so it shouldn't be used in the comparison with the Sigma. However, I think it is valid to compare the Nikon 35-70 F/2.8 with a hypothetical Sigma 35-70 F/1.8. The question is: How heavy the hypothetical 35-70 F/1.8 would be? I don't know for sure, but, again, the Fig. 29 again gives a hint. Although the graph stops at F/2.0 and is specific for a normal lens, the Fig. 29 suggests that the cost of raw optical glass for an F/1.8 lens would be several times more than for an F/2.8 lens. This agrees with my perception that the weight of a 35-70 F/1.8 lens would be several kg.

0 upvotes

I'm not convinced. I still think that the 20-35mm f/2.8 is a proper comparison. Yes, it's harder to get 104º on an FX sensor than to get 73º on a DX sensor, but it's also harder to get 73º on a DX sensor than to get 73º on an FX sensor. So is getting 73º on a DX sensor closer in diffiulty to getting 104º on an FX sensor or to getting 73º on an FX sensor?

I believe that it's much closer to the former (given the same lens mount and flange distance), but I also think that we'll have to agree to disagree about this.

1 upvote

I don't like hauling lenses around and especially short focal lengths. This would be useful. The AF comments have cast serious doubt though. Maybe an update?

0 upvotes

Its AF problem is with low-light at low contrast targets. It may well be more usable than one might think from the review. Aimed at eyes and faces it may well be just fine for the average wedding photographer.

0 upvotes

I think this is an impressive lens design...but why the AF issue? WHY? Come on Sigma, this MUST be solved, I have sold my entire set of Sigma lenses for the same reason: AF was horrible! Cheers...!:)

3 upvotes

I've been lead to understand that this is partly because the manufacturers of camera bodies often don't share the electrical connection protocols which sigma and others have to then reverse engineer, so to speak. So essentially it would be Canon being proprietal "Come one Canon, release the details...."

0 upvotes

I always wonder about the whole APS 1.8 vs FF 2.8 equivalency:

Are FF sensors as sensitive as APS-C, per mm^2? Because the equivalency only works if they are.

And I am not sure about that, seeing that APS-C outsells FF by more than an order of magnitude and correspondingly, the processes would be more optimized...

0 upvotes

The APS 1.8 vs 2.8 FF equivalence mentioned here is for depth of field ONLY !
About sensor sensitivity, if ISO is a standard scale to characterize it, then a 200 ISO FF sensor as the same sensitivity than a 200 ISO APS-C sensor. If not, then handheld light meters are just useless...

2 upvotes

Yes 200 ISO is 200 ISO no matter the sensor size (even if there are discrepancies between brands), but the noise is different.

FF sensors are about as sensitive per mm² as APS-C sensors because if you look at DXO Mark results, the ISO performance is proportionate to the sensor surface (for same generation sensors of course).

Comment edited 2 minutes after posting

3 upvotes

"it offers a 28-54mm equivalent zoom range, and promises similar depth of field control to an F2.8 zoom on full frame" -- It offers everything the same as 28-54/2.8 lens on full frame, not only FOV and DOF -- why is that difficult for the DPR staff to say the whole truth out loud?
Another thing they should have mentioned. The lens and most APS-C DSLRs it supports are just as large and heavy as an equivalent 24-70/2.8 lens + FF camera. But the latter offers better range, better resolution, etc. That's an important point if somebody considers acquiring this lens.

Comment edited 5 minutes after posting

3 upvotes

This is a lens for APS-C shooters. It doesn't matter what the full frame equivalent is. The full frame 24-70 F2.8 lens on aps-c would be Like 36/105 mm F4 on Full frame. But the choice is between lenses for people who have already chosen a sensor format. For these people Full Frame is non existent as long as they are shooting aps-c. But this is probably to hard to get into your thick skull.

Comment edited 42 seconds after posting

5 upvotes

When a person decides on an APSC lens, one doesn't compare it to an FF equivalent. Sigma also created this on that principle too, there isn't anything like this on APSC, besides this still is f1.8, giving faster speeds.

The constant aperture and the constant high IQ in all focal lengths just costed it too much size and weight though. I'm all for IQ but I don't see myself using this for hours.

1 upvote

Ive not worked with anyone that cares about equivalency ramblings. FF fans: Don't buy the lens. Simple. Kthnxbye.

2 upvotes

Sorry. Can't hear it anymore. There is no such thing as equivalent to APS/FF/m43...whatever. Hence this lens is exclusively for APS it's even more absurd talking about any FF equivalency. A 18-35mm F1.8 lens will always be a 18-35mm F1.8 lens.

I guess a lot of people will enjoy this lens.

3 upvotes

Stefan M is exactly correct.

1 upvote

I agree with Stefan M.

In fact, there are so many digital shooters using cameras with an APS-C camera that it would be better to move forward by just stating focal lengths for APS-C sensored cameras.
People are used to APS-C sensors, and the view that an 18 mm lens will give them on such a DSLR. There's no need for so many people to convert everything to full-frame equivalency when the majority of DSLR and mirrorless camera shooter aren't shooting FF.

I know some people will disagree, since the history of 35 mm film goes back decades, and SLRs have existed well before the advent of digital. However, I read that there are currently a far greater number of active DSLR users today than there were SLR in the decade before digital.

We don't state equivalent focal lengths and apertures in terms of medium format, and that used to be "full frame". I don't know why we treat 35 mm as some sort of standard, especially when those people who use the smaller sensor far outweigh FF users.

Comment edited 1 minute after posting

4 upvotes

Glad to hear I'm not the only one completely sick and tired of this equivalency nonsense. I use APS-C and full-frame 35mm digital. And (real full-frame) medium format as well. I even dare to use film sometimes.

I am odd, perhaps, but I do not walk around all day making equivalency computations and DOF charts, "light gathering" comparisons and whatnot.

I shoot.

0 upvotes

"The lens has a 50 mm focal length, or approximately a 35 mm equivalent focal length on an APS-C DSLR."

;)

1 upvote

At least in fixed lens cameras the lens should be described with picture angles like 80-4 diagonal degrees for a 20x zoom. Then the buyer would know exactly what the zoom range is no matter what the sensor size and the actual focal lengths are. People would get used to this quite fast, I think.

I shoot with APS-C and so called FF cameras and used to shoot also 120 film with several different film gate sizes, so I need not convert focal lengths to any equivalencies. It also seems that many are quite ignorant about the basic optical laws when doing the useless and often misleading/mistaken equivalency conversions.

And yes: 4x5" is the real "full frame", 135 is a miniature camera, originally made to use motion picture film...

Comment edited 2 times, last edit 1 minute after posting

3 upvotes

I totally disagree and probably the DPR staff too, they don't do that just because 35mm is considered standard or any important. It's only because we need one format to compare other formats. I didn't liked it when I was new to camera reviews but it made sense or understood it later on.

For example, if I am an APSC and a Nikon 1/RX100 user, I would like to have a standard unit to compare lenses of different formats and focal lengts.

2 upvotes

View angle would be a perfect measure of that. 60 degree lens would be the same on a smartphone, APS-C, 135, 6x7, 4x5, whatever.

0 upvotes

Dubious focusing in low light wide open is nothing new.
Canon's older primes provide inaccurate focus in low contrast situations. (From my experience: EF 85 1.8, EF 50 1.4, EF 50 1.8).

1 upvote

Would have been nice if they made a full frame version also!

0 upvotes

'Inconsistent autofocus in difficult conditions even after microadjustment' - for me this is the KILLER - sorry Sigma I won't be buying one....

0 upvotes

Canon 70D with new live view AF, should solve the problem. Too bad, the review didn't test that.

4 upvotes

Maybe it's a bit like some instances of the Sigma 85 1,4: different AF depending on whether coming from mfd or infinity, hopeless to micro AF adjust away.

0 upvotes

I second this. A in article assessment of the focus consistency addressed via DP-AF in live view with the 70D seems a must. These two products are THE current hot news for APS-C. If the reviewer does do a follow up please PM me with a link to your results.

0 upvotes

I used Canon 50mm 1.4 that wide open AF was not consistent, worse than my copy of Sigma 30mm 1.4.

1 upvote

Total comments: 275

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