24-70 is vastly superior in range to 29-57. I'd need at least one wider f/1.8 zoom on the 7D to make up for it.

Well, obviously, physics is not your cup of tea.
According to this ingenious calculation,
f/2.0 on sensor on camera with crop factor x5 will be equivalent to FF f/10, which is a complete nonsense.
There's a very simple way to check it - just use both cameras and compare actual DOF.

why. the performance of f 1.8 on aps c is no better that 2.8 on full frame. and there is an amazing range of 2.8 zooms. there is one measley f1.8 zoom for apsc and it doesnt even cover a particularly useful range. Full frame is better on strict image quality grounds why on earth would this tempt someone to switch

@Kodachrome200

Well, look at this from a different point of view...2.8 limits how much light the sensor gathers, but 1.8 is pretty fast. You get both 24 and 35mm at 1.8. If I had a Full-frame, I would consider getting an APS-C camera as 2nd camera just for this lens. Imagine now a 24-70 f/1.8?

There is atleast a 1 stop advantage in ISo going to full frame so again your argument holds no water

Oh it's prediction time, here's mine! In 2 years the new APS-C sensors will once again surpass full frame ones. Then you'll have to wait for the D5 and the 2DX to have it reversed back again.

Not switch. But ALL FF lenses are heavy, and with 1.5/6 crop this need be only one. Other crop lenses to be used are lighter & cheaper. So overall it's a better smaller lighter setup than going all FF. Cost...est. about 1400. IMO

7 minutes, you're getting old. :)

your dreaming yabokkie that 24-70 is a garbage lens this probably wont be and equivalnece does not apply to price

um.. what? I understand the benefit of "full frame" sensors but there is nothing inherently better with the lenses just because they have a larger imaging circle. Why not adapt large format lenses to your 35mm if bigger=better? And since when are aps-c lenses more expensive than the 35mm counterpart..? plus, its not like all lenses for 35mm were awesome.. I bet the nikon 35mm f/1.8 would run circles around most older 35mm lenses as well as collecting more than twice the light, its an aps-c lens and costs $199. You said we already have F/2.8 lenses, are you aware that you will be able to shoot with a shutterspeed TWICE as fast at F/1.8 than F/2.8. Stop trying to sh1t all over something new.

you are just full of sh1t. The nex5 uses the same sensor as a d7000 you say it takes better photos? dont just spout off like you know about something when you clearly don't.

Given same design, 1.6x larger in each dimension.

> equivalent lens for FF bodies.

we have better lenses for ages.
Canon/Nikon 28-70/2.8
Canon/Nikon 24-70/2.8
this Sigma is only 28-54/2.8, or 29-56/2.9 equiv. on Canon.

1.53x for APS-Cs other than Canon,
1.53^2 = 2.34 for weight and price (not cubic)
the price could go higher (up to cubic) for smaller volume.

not to mention that you get an integrated flash with entry-level DSLRs, so you have to factor in the cost of an external flash when making purchasing decisions.

but, ok, if you fant FF to win you can set the price of the Sigma lens to 3000 euro, 5000 dollars, 15000 credits or 300 bars of gold-pressed latinum, and win every argument using the same logic that "analysts" predict stock market trends. it's not like anything can go wrong.

Sigma and Tamron (f/2.8 zooms) are usually half the price of a similar Canon /Nikon (f/2.8 zoom) or about the same as a slower Canon /Nikon (f/4 zoom).
Given the price of Canon 16-35mm f/2.8 at $1400, I don’t see this (18-35mm f/1.8) lens going above that figure.
Sigma’s other lens in the range is the ‘slower’ 17-50mm f/2.8 at $700, so again $1400 seems the maximum they could go with this f/1.8.
For me $1,400 is still a lot, I’m hoping for something like $1,200 for release and later to drop at $1,050.

Sorry people if you're going to believe this lens is anything like 1500 or less, you're fooling yourself. Sigma got very self-confident with their pricing in the new lens lineup (and I absolutely do not doubt their right to be it - I actually lust for the 35/1.4 and 120-300/2.8, the latter got almost twice as expansive as the previous lens of the same specs). And it is a f/1.8 zoom after all - with all the bragging rights that come with it (if you don't do the maths). So I really would be surprised by an initial street price in the region of 2000€.

$2,000 would make it the most expensive lens built for APS-C sensor only (way more than any Nikon DX).
I'm not saying nobody ever put a $2,000 glass on a DX body, but I doubt anyone will buy a $2,000 lens which is designed for crop only.
Do you think Sigma first designed and built the lens, and only afterwards established the price,… or was it the other way around? So either Sigma didn’t make any market research, or they did it and found that there are lots of DX users willing to pay that amount - to justify development of a new lens.
Time will tell!

better buy one for better cost-performance.

Let's wait 'til we see the likely aberrations,,, before we start getting all moist.

Have you seen the performance of the new Sigmas? I own two of them. Impressive. Very likely this one is no different.

A group portrait at f1.8 !!! You need to stop down for more DOF for a group portrait.

wouldn't call it break-through.
it's an f/1.8 for APS-C only,
that can do the same work as an f/2.8 on 35mm format.

if there is a break-through, it's the equivalent flange-back,
which is longer for APS-C, why we see a bloody 5 SLD plus
4 glassmold aspherical.

the fact is, nobody else have done it, specially for canikon aps-c (not following m4/3) -> breakthrough

okay, a break-through of neglect mind.

Canon and Nikon are abandoning the APS-C SLR for a simple reason, it's not technically competitive as, of higher cost/lower efficiency than 35mm format.

an APS-C 16-46/1.8 can do the same work but will be more difficult to make, cost more than 24-70/2.8.

This lens is a f1.8 lens NOT a f2.8 lens. DOF for sure will be similar but NOT speed. The f1.8 lens will be more than a stop faster which is a big deal for low light shooters.

"Canon and Nikon are abandoning the APS-C SLR" - Abandoning? I see something quite contrary (eg. only non-AA alternative to 800E in Nikon lineup is APS-C camera). The fact that there are more FF cameras recently doesn't mean anyone abandons APS-C. Don't be ridiculous.

"Canon and Nikon are abandoning the APS-C SLR for a simple reason, it's not technically competitive as, of higher cost/lower efficiency than 35mm format."

yes, because $700 is more expensive than $2500. when you only have so much to spend on a "good" camera, what do you do, buy what you can afford or just give up?

I find it interesting.
why you stop at f/1.4 and not go for f/1.0 or f/0.4?

Maybe, but there is a giant installed base of APS-C and thus less risk. If this is successful FF will follow with a base of believers to sell to on the strength of this lens.

but with the crop you're stuck with one magic lens. With the 6d you can put on a F1.2 lens (to make a light sucking machine) to a pancake lens (low weight and cost.) It works it's FF magic on all lenses. But I'm not knocking anything, this is a cool lens, but its just another trade off--not a B&W decision.

@vodanh1982. Lets get real, why you need that much resolution and do you shoot with tripod and perfect focus all the time?
These days, resolution is not a limiting factor like it used to be in the days of 6MP cameras. Besides I see this new sigma lens extremely useful for video (2 Megapixels)

@TKO. C'mon, what are the chances of most people able to afford a F1.2 lens, and there is nothing to stop you using it in crop bodies.

It's not "real equivalence" until you fix the fact that 18-35mm on a 60D is only equivalent to 29-56mm on the 6D.

So, toss in a 24mm f1.8, the Sigma weighs in at $550 (It also weighs 485g, and takes different size filters than the 18-35).

Then toss in a 43mm f1.8. What? You say Sigma and Canon don't have one? Why not? Pentax does. How about a Canon 50mm f1.8. It's a touch long, but just $125. Of course, it has not very pretty bokeh, yet another filter size, and 130g.

Now, how much "equivalence" is there between a Canon L zoom and a Sigma? Let's fix that, too, and set the 6D up with a Sigma 24-70mm f2.8. Sauce for the goose and all.

6D + Sigma 24-70 = $2725
60D + Sigma 18-35 + Sigma 24 + Canon 50 = $2475

That's only part of "real equivalence". How do you put a price on these things?

6D - bigger, brighter viewfinder

60D - hassles of carrying three lenses, with three different filter sizes, an extra 615g, the hassle of changing lenses, the need for a bag where you might have gotten away without one?

"@vodanh1982. Lets get real,"

You keep using the word "real". I don't think it means what you think it means.

What are the chances this lens will cost $1100? I'd expect closer to $1700-2000. Remember that an Olympus Zuiko 14-35 f/2 cost $2300. Or the price will be $1100 with optical quality much lower than Canon's 24-70 Mark II and even mark I :).

And Joseph above summed it up pretty well : add an extra wide lens to cover 24mm equivalent and a 50mm lens to cover the ~70-75mm equivalent. There is a very good reason why 24-70mm FF lenses are so popular -- both 24mm and 70mm are very useful.

@Joseph. Is true that the Sigma doesn't go as wide or long but that is the beauty of it for people that dont want to compromise image quality for focal range or need just that focal range. Of course IQ on the Sigma is yet to be assessed.
Perhaps a better comparison is against the Sigma 24-70 f2.8 which is cheaper than the Canon. But still you are left with $1000 if you go the crop body route.
I mentioned equivalence in terms of rough value, not accurate metrics.

@ppastoris. Considering the amount of comments (mostly positive ones) this lens has received, it could easily be considered product of the year.
In other words, people find this lens very interesting, myself included.

Photato, the lens is certainly interesting. But how interesting and how valuable it is will depend on its price and optical performance. If it costs $2000 and has an optical quality of a $1300 full-frame Canon or Tamron 24-70 f/2.8 lens, then it's not a very good value as it has narrower AoV range and isn't much lighter or smaller. If it costs $1300 then maybe it's not a bad choice for those with a big investment in APS-C cameras and lenses.

As to the "excited comments" : I bet many of those excited people tend to think of the lens as 27-52 f/1.8 35mm equivalent, which it isn't. When you realize that this lens on an APS-C is merely an equivalent of 27-52 f/2.8 on a 35mm camera your initial excitement goes away ;).

@pastoris. Lets put it this way. I need the focal range and aperture this sigma has. There is nothing like this in the APS-C market. The other option is to go Full Frame but that means more money and abandoning my crop lenses.
I know the sigma start at 29mm FF equivalent and that is fine.
Now, if this lens has bad optical geometric distortion and CA, then I'd just pass.

Can't disagree with you -- if you understand the limitations of the lens and own a lot of APS-C only equipment already then this lens could be perfect for you.

On the other hand, I personally would consider switching to a full-frame system with all the extra niceties that it gives you : zoom lenses with really well chosen focal length ranges (e.g. 17-40, 24-70, 70-200), effectively one stop brighter primes (e.g. FF f/1.4 is effectively f/2.2 on APS-C), and finally generally better DR at the base ISO. I did exactly that when 5D Mark II came out and never regretted ever since :-P.

These whole calculations about "light sucking machine" assume that FF is equally 1EV better in low light than APS-C. Meanwhile that's not always the case and through the history we've learnt that APS-C not only can be closer than that but even outrun some FFs. So I wouldn't go as far as saying that suddenly f/1.2 glass becomes f/1.7 - it's still 1.2 only on APS-C, major consequence of it being field of view and depth of field.

And to end the story - if you follow this "light sucking machine" paradigm - show me your 135 f/1.7 on full frame - cause on APS-C according to this logic I can get it easily if I shoot Canon and got enough $$$. An ultimate perfect portrait lens.

A joy to 7D users, crop sensor users in general.

sensors are cheap and are getting cheaper. little we can save by having small sensors. what's the point to have a small sensor behind a big lens?

sensor size should be chosen that quality lenses can be made easily. if the quality requirement is low, the lens and sensor size can be small. or if the size is the priority, the image quality will be low (Google Glass).

also there are different APS-Cs. mirrorless ones with short back-focus are good, SLRs are bad.

"APS-C has 1 stop worse ISO noise" - that's not an universal truth. It often is, but let's face it - year ago it wasn't that easy and APS-C was much closer than that. I'd say that depending on comparison even right now APS-C is closer than that.