Sigma 18-50/2.8 for Fuji X mount tested on 40Mpix sensor

[BeatX]

Hello everyone

Im looking for universal zoom for using it exclusively on vacations/holidays/hikes.
Currently there is Tamron 17-70/2.8 on my radar, but before buying it, I thought I'd give Sigma 18-50/2.8 a try.
I heard many times that this lens is very good optically (very sharp etc), and its super compact size and low weight is something what attracts me.
So I rented Sigma 18-50/2.8 and I've needed only half hour of using it, to be 100% sure I'm sending it back
Usually, I'm trying in my reviews to be more precise and detailed, but Sigma 18-50/2.8 optical flaws and optical compromises are so big and obvious, that this time I didn't bother to do more in depth test and comparison against my other lenses.

Anyway, like always I will be brutally honest and as much unbiased as I can - in my opinions and insights.
Below are lab test with all mtf and charts You need:
https://opticallimits.com/fujifilm/sigma-18-50mm-f-2-8-dn-dc-contemporary/
https://www.ephotozine.com/article/sigma-18-50mm-f-2-8-dc-dn-contemporary-rf-fit-lens-review-36921

Sigma 18-50/2.8 build quality is very much ok, although casing is made of plastic - but it makes a very solid impression.
Nothing creaks - whole parts are perfectly fitted and assembled.
Zoom and focus rings turns smoothly, but I think in new Fuji kit lens all three rings turns even smoother and have more premium feel to it.
AF is blazing fast, almost completely silent and very accurate (in AF-S at least)
I didn't do proper AF-C test, so no clue if this lens can keep up with average moving subjects.

Now.. image quality.
First of all, it's really hard to objectively evaluate this lens, because on the one hand its size and weight while maintaining constant f/2.8 aperture for 18-50mm focal range (for aps-c size image circle) is a true miracle of miniaturization.
Really big applause for Sigma for creating such compact lens for aps-c platforms.
But on the other hand, to achieve such low weight and dimensions Sigma made huge optical compromises, which are visible to the naked eye and which are simply unacceptable to me.
Although I guess that for people with a greater tolerance for image quality, Sigma 18-50/2.8 will be absolutely fine

So, this lens is sharp at every aperture (even wide open) - but apart for 50mm focal length - only in the image center.
Frame edges on Sigma 18-50/2.8 at 18mm are so bad that they literally masked huge decentering in my lens copy.
(right side of the image is always much softer than left side)
This alone should make you understand how bad image quality is in the corners - at least for 18mm.
In general, image sharpness @18mm in Sigma 18-50/2.8 is very poor (at least for 40Mpix sensor resolution), period.
But when I've downscaled images to 26Mpix, results were not that much better (check sample images)

Corner sharpness is gradually improving while zooming in, but in my opinion only from 35mm corners are usable (more less XF 35/1.4 level of acutance) and Sigma 18-50/2.8 is finally fully usable @50mm in the entire frame.
CA is big, distortion is big, vignette is big etc.
Not a big deal, but poor corner sharpness basically across the whole zoom range is not caused due to to lens barrel/pincushion distortions - turning off in LR lens optical corrections don't help much.

So, I will not dig in further - You get an idea what are we dealing it with here.
Below I've posted full size sample images from 40Mpix sensor, at lens peak performance @f/5.6
This time however without link to .RAF files, as basically nobody cares in evaluating raw files
Photos are demosaiced in LR with "Enhance" tool, with default settings - only edits I made is to equalize exposure and recover some highlights (LR lens corrections are on)













Some bokeh/rendering test shots:









So, if You get close enough You can get some medicore results with bokeh, but in real use for 18/2.8 combination in normal distances there is hardly any play with bokeh/shallow DOF





Imo images are just flat, dull and boring.
Nothing unexpected - as every single zoom lens is acting like this, but I want to point out it clearly: constant f/2.8 aperture in Sigma 18-50/2.8 is only convenient because of exposure control, where apart from 50/2.8 combination in my eyes, images will come out flat and boring like from every other zoom with variable aperture.

So, who is this lens for?
I don't know to be honest
I guess for someone who wants constant f/2.8 aperture at every cost, and that about it.
Perhaps for some street shooters? But I heard, that for street photo You close aperture to at least f/5.6 anyway.
For low light photography f/2.8 aperture is very so so.
Sigma 18-50/2.8 will give poor results in landscape applications (for big prints at least), so even below average performing Fuji 16-80/4 is more appropriate option due to its greater zoom range and build in IS.
Perhaps Sigma 18-50/2.8 is ok for someone who want to do documentary of every day family life using only one lens?
It is some option, but for such use I would recommend of choosing new Fuji kit lens, which:
- has more useful focal range
- has much better overall IQ between 23-35mm focal ranges
- has internal zoom mechanism (!)
- has zoom ring which turns in same direction as other Fuji zoom lenses
- has dedicated aperture ring
- has WR
- has better build quality (imo)
- has even smaller dimensions and weight

Seriously guys, think twice before You will decide for Sigma 18-50/2.8 over Fujinon 16-50/2.8-4.8
Just as an reminder, here is my review of Fujinon 16-50/2.8-4.8
You can add to Your kit super cheap, super lightweight and compact Chinese MF lens, like TTArtisan 35/1.4 which will be fantastic complement for Fuji new kit lens.
And such combo (XF 16-50/2.8-4.8 + TTArtisan 35/1.4) will give much more creative options and finals results, than Sigma 18-50/2.8 alone for every scenario I can think off.
But maybe there is some sensible use for Sigma 18-50/2.8.. hard to tell.
If someone know such, please - let us know

At the end, because there is fantastic new Fuji kit lens, I don't recommend of buying Sigma 18-50/2.8
It has too many compromises for only one advantage in return: constant f/2.8 aperture.
Imo it's not worth it.. but YMWV.

I'm giving this Sigma 3.5 stars just because it's the world's smallest and lightest APS-C lens with a constant f/2.8 aperture, what is truly jaw dropping (its size and weight)
But that's about it, optically this lens rating should be 2.5 out of 5 stars in my opinion.

I hope this helps

--
My gallery: https://www.flickr.com/photos/maciej_k/

 

[coolrunnings]

i also got rid of this lens after 3 months myself. never tried it on the 26 MP sensor but on the XT5 40MP sensor minus the brighter aperture it performed worse that the XC15-45mm that i had maybe my copy was bad too i guess, happier with the new XF16-50 i got discount bundled for $300 but generally i gravitate to primes over zooms whenever possible.

 

[Erik Baumgartner]

Hello everyone

Im looking for universal zoom for using it exclusively on vacations/holidays/hikes.
Currently there is Tamron 17-70/2.8 on my radar, but before buying it, I thought I'd give Sigma 18-50/2.8 a try.
I heard many times that this lens is very good optically (very sharp etc), and its super compact size and low weight is something what attracts me.
So I rented Sigma 18-50/2.8 and I've needed only half hour of using it, to be 100% sure I'm sending it back
Usually, I'm trying in my reviews to be more precise and detailed, but Sigma 18-50/2.8 optical flaws and optical compromises are so big and obvious, that this time I didn't bother to do more in depth test and comparison against my other lenses.

Anyway, like always I will be brutally honest and as much unbiased as I can - in my opinions and insights.
Below are lab test with all mtf and charts You need:
https://opticallimits.com/fujifilm/sigma-18-50mm-f-2-8-dn-dc-contemporary/
https://www.ephotozine.com/article/sigma-18-50mm-f-2-8-dc-dn-contemporary-rf-fit-lens-review-36921

Sigma 18-50/2.8 build quality is very much ok, although casing is made of plastic - but it makes a very solid impression.
Nothing creaks - whole parts are perfectly fitted and assembled.
Zoom and focus rings turns smoothly, but I think in new Fuji kit lens all three rings turns even smoother and have more premium feel to it.
AF is blazing fast, almost completely silent and very accurate (in AF-S at least)
I didn't do proper AF-C test, so no clue if this lens can keep up with average moving subjects.

Now.. image quality.
First of all, it's really hard to objectively evaluate this lens, because on the one hand its size and weight while maintaining constant f/2.8 aperture for 18-50mm focal range (for aps-c size image circle) is a true miracle of miniaturization.
Really big applause for Sigma for creating such compact lens for aps-c platforms.
But on the other hand, to achieve such low weight and dimensions Sigma made huge optical compromises, which are visible to the naked eye and which are simply unacceptable to me.
Although I guess that for people with a greater tolerance for image quality, Sigma 18-50/2.8 will be absolutely fine

I've seen and processed a bunch of RAW images from this lens and, while I don't think it's quite as bad as you make it out to be, I do agree that it's not anywhere near as good as some reviews suggest, especially for those averse to post processing. It's good that you show pretty much what you get from a RAW file with only the basic default corrective processing - not the greatest contrast (and significantly worse around the periphery), not the greatest CA/fringing performance (and significantly worse around the periphery), OK sharpness in the the center but, again, significantly worse around the periphery. The thing I dislike most about it is a tendency towards a not always subtle magenta/purple haze/color cast across most images. I didn't look closely at all the images, but I don't see any major decentering - both sides look about equally soft to me. Very nice images can be produced with this lens, and this is mostly stuff that can be dealt with pretty easily in post, but do you really want to have to do that with every image on a regular basis? I don't. Images from most lenses can generally be improved with some corrective tweaking but, in my experience, RAW images from the Sigma 18-50 pretty much always require more than their fair share for the best results. Maybe Capture One's or DxO's proprietary lens corrections do a better job automatically?

If size, weight and constant f/2.8 are the primary concern, then this lens is probably the way to go, but the optical compromises, along with backwards zoom ring, missing aperture ring, and the 18mm limitation at the wide end, make alternate (larger) options a lot more attractive to me. I'd much rather carry my mk1 16-55 around than one of these.

Here are the original images with a few tweaks to correct the CA, contrast, sharpness issues (primarily around the periphery) along with a subtle color adjustment to null out the magenta color cast. Not the greatest light, so still not the greatest photos, but they now look, to me anyway, generally sharp and relatively decent overall, it's too bad you don't get that from the get-go.




With a few corrective tweaks

With a few corrective tweaks

 

[John Bean (UK)]

Your review doesn't surprise me. I've never used this lens on Fuji but a few years back I bought one in Sony mount - and didn't keep it.

Like you, I found no comparison in real-world results with the glowing reviews I had read. In particular the images lacked any kind of "bite" and were flat and characterless. I don't rate "sharpness" in the vague way it's used to describe characteristics, I'm more interested in real detail and micro-contrast which are both lacking in the Sigma.

You can sharpen up the dull images for sure, but then you could have done just as well (perhaps better) with a phone camera. Not one of Sigma's best; it reminds me a lot of the absolutely terrible kit zooms they churned out for cheap film SLRs back in the day.

 

[Xbot]

I have this lens and use it on an X-T5. Mine doesn't seem to have the decentering issue yours did, but I agree that once you move out from the center of the image it's only ok at best even when stopped down.

However, it still has its uses for me. For family or people shooting especially when the light gets low, it does perfectly well. I've used it for family portraits, for example, when the flexibility of a zoom prevents delays to switch lenses. Those are images that are never going to be printed very large so absolute sharpness doesn't matter. And, in any case, some softness on the borders won't matter to anyone.

 

[jonikon]

It seems that I have read many posts on this forum raving about the virtues of the Sigma 18-50 f2.8, but despite those and good reviews I was was skeptical of how an inexpensive small f2.8 lens of this type could be that good. Yours is the first real negative post I have seen for the Sigma 18-50 f2.8 on this forum, but I don't doubt your honesty and applaud your taking the time to do your testing to post it. From reading verified buyers reviews of the Sigma 18-50 f2.8 it appears there are quality control issues with this lens resulting in some bad copies, which complicates a buying decision to purchase this lens.
I was very tempted to purchase the Sigma 18-50 f2.8 lens, but in the end I purchased the XF 16-50 f2.8-4.8 and have been very satisfied with its optical performance, build.quality, and small size and light weight. For me the 16mm wider end and excellent sharpness of the Fujinon XF 16-50 trumped the constant f2.8 of the Sigma lens.

 

[MarcosV]

Thanks for posting your well thought out review in the Sugma 18-50/2.8.

FWIW, I also own the Tamron 17-79/2.8, Sigma 18-55/2.8, XF 16-55/2.8 Mk I and now Mk II.

I love the small size and low weight if the Sigma. It was good enough I the center wandering was a great option for snapshots I n vacation and at family parties.

As soon as I bought the XF 16-55/2.8 Mk II, I never used the Sigma again.

The Sigma 18-55/2.8 is a favorite for friends with 24 MO sensor cameras like the X-M5. It is the most popular lens I loan out.

I do use the Sigma 10-18/2.8 as my ultra wide. XF 10-24/4 and XF 8-16/2.8 are too big/heavy for my sling bag --- they work better if I am lugging a camera backpack.

 

[dccberry]

As someone who is at least as picky about optical quality as the OP, I would say that, for what it is, ( a small, inexpensive, fast walkaround lens ) the Sigma does a great job. It's not perfect, but for general hiking / travel photography, it produces really nice images on any of the Fuji sensors. The points he makes are valid, and I would not discourage anyone from using it either. Optical perfection is a myth, unless you're talking about the XF 200f/2 or a few other high-end lenses, and although I have not used the Sigma on a paid shoot, I would certainly do it if that was the lens that was available to me at the time.

The Big Picture Framing & Photography in Port Townsend WA

The Big Picture Framing & Photography (Linda Dugan & David Conklin) offers custom traditional, modern and archival framing, image conservation & restoration, fine art photography, as well as commercial, editorial, portrait, movement, dance photography, high-quality art copywork & gic

www.conklinphoto.com

 

[BeatX]

Erik, I know that photos I have shown as a sample images do not represent any other value, apart from the possibility of assessing optical performance of Sigma 18-50/2.8
I intentionally chose this and not another scenery, so that in addition to the possibility of evaluating lens acutance, one could also check CA levels.
Low contrast from forecast weather, and tree branches against cloudy sky in the background are great for this purpose

However, it is worth noting that this is an extreme situation for checking lens CA levels.
In normal use, there would certainly be no such big problems with Sigma 18-50/2.8

 

[BeatX]

For family or people shooting especially when the light gets low, it does perfectly well. I've used it for family portraits, for example, when the flexibility of a zoom prevents delays to switch lenses. Those are images that are never going to be printed very large so absolute sharpness doesn't matter. And, in any case, some softness on the borders won't matter to anyone.

Yeah, I imagine that for documentary type of photography (in particular, shooting people), Sigma 18-50/2.8 can deliver nice results, and for sure its very convenient.

Shooting video also comes to my mind, where Sigma's optical flaws should not be a problem

 

[BeatX]

It seems that I have read many posts on this forum raving about the virtues of the Sigma 18-50 f2.8, but despite those and good reviews I was was skeptical of how an inexpensive small f2.8 lens of this type could be that good. Yours is the first real negative post I have seen for the Sigma 18-50 f2.8 on this forum, but I don't doubt your honesty and applaud your taking the time to do your testing to post it.

Thank You Much appreciated!

You can be sure of one thing when it comes to my tests, comparisons and reviews of photographic gear and software - I always write truth, hiding nothing, and Im trying to be as unbiased and objective, as my mind allows me to be hehe
When there is something to praise, I praise equipment by clearly emphasizing its excellent parameters or features.
When something that passes through my hands has some obvious flaws, I will point them out loud and clear.

From reading verified buyers reviews of the Sigma 18-50 f2.8 it appears there are quality control issues with this lens resulting in some bad copies, which complicates a buying decision to purchase this lens.

Can't confirm that, but I suppose it could be the case.

I was very tempted to purchase the Sigma 18-50 f2.8 lens, but in the end I purchased the XF 16-50 f2.8-4.8 and have been very satisfied with its optical performance, build.quality, and small size and light weight. For me the 16mm wider end and excellent sharpness of the Fujinon XF 16-50 trumped the constant f2.8 of the Sigma lens.

I think You made good decision for choosing Fuji new kit lens over Sigma 18-50/2.8
At the time I was writing my review of XF 16-50/2.8-4.8 I didn't have a comparison to Sigma 18-50/2.8, so it was hard to say which lens was in general more reasonable choice.
But now I'm absolutely certain that for most users Fuji new kit lens is simply overall better option.

However, I realize that there will be users for whom features and optical performance of Sigma 18-50/2.8 are just great. Like for Xbot

 

[Pictures shooter]

BeatX,
I also have Sigma 18-50 and my impressions are close to yours, but in not all details.
First, it seems my copy is just passed better QC and accordingly optically better,
e.g., my copy does not suffer decentric at all, and it's really significant for an overall optical quality.
All the rest of the optical unpleasantness of this lens you described are familiar well for me, but again, they are not so dramatically with my copy.
E.g., I found that this lens is able to make a good job in the range about 30...50mm, not only at 50mm. Talking about 50mm exactly, my copy provides an absolutely excellent picture at 50mm FL, and 30...40mm range is enough good too, but might not be excellent in terms of perfect expectations.
Nevertheless, I'm absolutely agreed with you that Sigma 18-50 is able to provide just mediocre at best picture quality at the wide range, roughly somewhere about at 18...28mm, and its quality at the widest 18mm is close to the quality of cheap plastic zooms of mirror cameras age twenty years ago, and it's not good for landscape genre at all.
Been having said all this above, I nevertheless believe if we're ready to spend enough time post-processing we may get not so bad, may even the very good pictures and at wide range too.
And in the end, I'd like to remind a banality we often forget about. If we use the lens with nice ergonomics that's a pleasure to use mainly to record home memories, all our requirements to optical quality do not make too much sense; in other words, pictures with our lovely wives and/or children will be great for our hearts in ten or twenty years after, irrespectively would we be able to find there some distortions, aberrations or, let say, so unpleasant stuff as a sharpness failing of on the frame edges.

 

[Erik Baumgartner]

Erik, I know that photos I have shown as a sample images do not represent any other value, apart from the possibility of assessing optical performance of Sigma 18-50/2.8
I intentionally chose this and not another scenery, so that in addition to the possibility of evaluating lens acutance, one could also check CA levels.
Low contrast from forecast weather, and tree branches against cloudy sky in the background are great for this purpose

However, it is worth noting that this is an extreme situation for checking lens CA levels.
In normal use, there would certainly be no such big problems with Sigma 18-50/2.8

Not a great scene for a compelling image, but very good for testing purposes. You're right, the significant CA in the tree branches isn't going to show up in most photos, but I see that slight (and sometimes, not so slight) purplish color cast (also CA, not WB) turn up in a lot of otherwise nice photos. That, and the 18mm wide end limit is more than enough for me to eliminate this lens from mid range zoom consideration. Been there, done that. A mid range APS-C zoom needs to go to (and be great at) 16mm, IMO.

 

[BeatX]

BeatX,
I also have Sigma 18-50 and my impressions are close to yours, but in not all details.
First, it seems my copy is just passed better QC and accordingly optically better,
e.g., my copy does not suffer decentric at all, and it's really significant for an overall optical quality.
All the rest of the optical unpleasantness of this lens you described are familiar well for me, but again, they are not so dramatically with my copy.
E.g., I found that this lens is able to make a good job in the range about 30...50mm, not only at 50mm. Talking about 50mm exactly, my copy provides an absolutely excellent picture at 50mm FL, and 30...40mm range is enough good too, but might not be excellent in terms of perfect expectations.
Nevertheless, I'm absolutely agreed with you that Sigma 18-50 is able to provide just mediocre at best picture quality at the wide range, roughly somewhere about at 18...28mm, and its quality at the widest 18mm is close to the quality of cheap plastic zooms of mirror cameras age twenty years ago, and it's not good for landscape genre at all.
Been having said all this above, I nevertheless believe if we're ready to spend enough time post-processing we may get not so bad, may even the very good pictures and at wide range too.
And in the end, I'd like to remind a banality we often forget about. If we use the lens with nice ergonomics that's a pleasure to use mainly to record home memories, all our requirements to optical quality do not make too much sense; in other words, pictures with our lovely wives and/or children will be great for our hearts in ten or twenty years after, irrespectively would we be able to find there some distortions, aberrations or, let say, so unpleasant stuff as a sharpness failing of on the frame edges.

Yeah, sure - I see what You mean.
Like I wrote in my first post, Sigma 18-50/2.8 should work just fine for documenting everyday family life, to take snapshots on meetings with friends and so on
In general, for documentary type of photography it's not a bad option (under condition, that one is not so crazy about lens rendering like I'm haha)

 

[BeatX]

A mid range APS-C zoom needs to go to (and be great at) 16mm, IMO.

Could not agree more
For me 16mm on wide end is must, for standard zoom lens.

But to be honest, I wouldn't mind if Fuji designed a 13-50mm standard zoom lens.
It could be with variable aperture, or fixed f/4 aperture, just give me that extra couple mm on wide end with decent sharpness for wide angle landscape shots.
Like Sony 20-70/4 G, or Panasonic Lumix kit lens 20-60/3.5-5.6
These two zooms don't let me sleep
I would buy such Fujinon XF 13-40/3.5-5.6 R WR LM with IQ similar to new Fuji kit lens in first day of its release..
40mm vs 50mm is not a big deal, but 13mm vs 16mm makes a noticeable difference imo.

Olympus 8-25/4 PRO is evidence, that such lens CAN be designed and it still can have reasonable size and weight + outstanding and consistent IQ across the frame, in whole zoom range.

--
My gallery: https://www.flickr.com/photos/maciej_k/

 

[pifilos]

Seriously guys, think twice before You will decide for Sigma 18-50/2.8 over Fujinon 16-50/2.8-4.8

 

[BeatX]

Filippos, many great photos on a new stage of your photographic journey

Interesting lens choices You've made.
I'm just wonder.. why there is no Sony 20-70/4 G in Your gear kit (?)
Isn't this lens is one of best available travel zooms on the market right now?
Personally, I do rate Sony 20-70/4 higher than Fuji new kit lens, or even slightly more than XF 16-55/2.8 mkII, for travel/hikes/holiday photography.

--
My gallery: https://www.flickr.com/photos/maciej_k/

 

[Hans Z]

Appreciate the time you took to make the review and share it with us, BeatX.

It's hard to find a good zoom lens that is compact, and especially a good copy. Of course if one does not mind the optical compromises, then there is plenty to choose from. For my own part I like to zoom in on the details of my pictures so optical imperfections do bother me. Not right or wrong, just part of my own criteria.

When I first entered the Fujifilm ecosystem, coming from Canon, I had the 18-55mm kit lens that unfortunately was plagued by a soft side, so after that I have only purchased prime lenses. Now I am contemplating adding a Nikon Z6III/Z8 with the 24-120mm zoom. But Ideally I would be able to test a lens copy in the store before committing.

It therefore valuable to see tests like this that complements subjective statements about the quality of a lens. The elusive factor that is hard to eliminate is the copy-to-copy variation that exists despite modern technology.

 

[pifilos]

Filippos, many great photos on a new stage of your photographic journey

Interesting lens choices You've made.
I'm just wonder.. why there is no Sony 20-70/4 G in Your gear kit (?)
Isn't this lens is one of best available travel zooms on the market right now?
Personally, I do rate Sony 20-70/4 higher than Fuji new kit lens, or even slightly more than XF 16-55/2.8 mkII, for travel/hikes/holiday photography.

 

[BeatX]

Sure thing Hans!
Im happy that my mini review help You make a some sort of decision

Nikon Z 24-120/4 S is indeed one of very few super-zooms for holiday/travel, which I would suggest to pay a closer look if one is looking for such.

Nikon Z system in general is very attractive to me in terms of ergonomics, image quality, colors, etc, and just for Nikkor Z 35/1.4 lens alone I would be willing to switch from Fuji X to Nikon Z.
Nikkor 35/1.4 + Nikkor 24-120/4 S would be a very reasonable (for me) travel set, but the size and weight of this zoom put me off a bit.
Besides, I personally value wider angles more than closer zooms, which is why I always think back to Sony 20-70/4 G when I think about a zoom for vacations.
Ideally for me would be to get Nikon Z6III + Nikkor 35/1.4 S + Sony 20-70/4 G and connect 20-70/4 via Sony E -> Nikon Z adapter
Supposedly such adapters provide very good AF work and there are no problems with sharpness of photos across the frame:

https://flic.kr/p/2qScbfv

Sorry for OT