So I decided to buy a Sigma zoom.


EOS 5D Mark IV
Feb 1, 2013
After some time and consideration, I decided to buy a Sigma 120-400 f/4.5-5.6 OS zoom lens, to use with my crop camera (for now). I apologize if this mini-review is too might help if I tell you I compare this lens with other Canon L lenses I have tried, and own. I did consider buying the 150-500 Sigma instead, but ultimately I wanted to try this one more.

I had originally considered renting a Sigma zoom. But the only one for rent, is the 50-500 (besides the big 120-300 f/2.8 OS...I'm waiting on the new "art" version with the dual fluorite elements, before renting that one)...and I decided I could do without 500mm...especially considering the reviews that said above 400mm, that lens wasn't very sharp. Funny how that kind of thing can show up in their other zooms...

This is the third Sigma lens I have bought. (I also owned a Sigma camera, and loved it, despite its quirks.) The first Sigma lens was in early 2009, a 17-70 (non-OS, first introduced possibly somewhere around 2004-06?). It was incredibly sharp with brilliant color and contrast. However, it refused to ever AF correctly no matter what. I finally sold it last year (for nearly what I paid for it new), but did hate to see it go anyway. One of my images done with it, got published in Outdoor Photographer last year.

My second Sigma lens purchase, was in Dec 2012; a 17-50 f/2.8 OS. This one has more barrel distortion than the 17-70 at the wide end, but overall, the color and contrast are similar, the bokeh is better, smoother, and obviously more pronounced/artistic...the sharpness is similar...the CA is low, and thus similar...and the AF accuracy is basically dead on throughout the zoom range with no micro adjustment necessary! The OS is a true 4 stops, and works perfectly. I think a semi-pro or even full-pro event shooter or portrait photog, could churn out spectacular work with it. If I decide to sell this lens in the future, I will hate to see it go. They do hold their value very well on the used market (another deciding factor at purchase). The reviews all seem to be's better than the Tamron 17-50 f/2.8. It also seems to make the much loved but over-hyped Canon 17-55 f/2.8 IS, seem to also be over-priced. If it is any better than this Sigma, it's not worth paying the $300 premium for a lens that still can't be used on full frame bodies. Ok, getting off my soapbox on that one, haha!

But back to the new lens...the third Sigma I have ever bought. I have to say, the build quality is very nearly Canon "L" quality. The fit and feel of the lens hood, the feel of the lens body, the feel of the focus and zoom rings...the feel of the tightness of the barrel as it telescopes outward...the printed all looks and feels like it might cost more than it does. And the lens ring/tripod mount/grip...well holy ****, that thing is very close to the equal of the very best Canon L supertelephoto's !!! I absolutely love it! Fits perfectly in the hand for carrying upside down or any angle, with the perfect distance from the lens body, and the perfect molded finger indentions. This lens was introduced in either 2007 or 2008, I believe. Sigma really are turning into a terrific lens and camera company, in my opinion (optical imperfections of the lens aside).

It arrived March 4. After spending only about 2 hours shooting with it so far (and even longer perusing and tweaking the files on computer)...It has less contrast than I thought it would. (I already knew it had less than the Canon zoom, thanks to the reviews and folks on this forum), but it's definitely still usable with post editing...and has a nice color balance. It has quite a bit more contrast below 200mm, than above, so that's at least a plus. It's softer than the Canon 100-400...yes...but not by a lot (however, it possibly is noticably softer than the Canon all the way at 400mm...but up to about 340mm it's still usable for very mild cropping). Sharpening in ACR seems to be mostly from 1.4 to 2.3 pixel radius. Far from ideal, but still usable for a medium amount of cropping (definitely not for a large amount of cropping...where sharpening from about 1.3 down to .5 pixel radius is necessary. The Canon 400 f/5.6L prime...was good for that. But it doesn't have stabilization, isn't a zoom, and costs more). And keep in mind, this is via a crop camera. I attribute some of the softness to a lack of focus accuracy/consistency (which again, I was warned about on this forum...I'm very glad to have you all!). Overall, it's not remotely as sharp as my excellent copy of the Canon 70-200 f/4L (non IS...I didn't think it would be)...but for a zoom of that Canon's size and price range ($600)...nothing in the world can come close to that one anyway, in my opinion. Certainly the 24-105L does, but that's a wide zoom.

One aspect I like a lot, is the close focus ability. The impression I got was that only the Canon zoom could focus closely...but this one does too.

The biggest problem, and biggest enemy of sharpness with this Sigma lens, is the "OS". It blurs the image a bit when in use. It's a shame, because the stabilization actually works quite well, and is closer to 4 stops (rather than the negative reviews that say it's just 2; although I'm not convinced how well it works in panning mode...I need to experiment more with that). I got something recognizable at 1/10 second at 400mm on my motion blur, just the OS fuzziness. However, even with a really fast shutter speed, that same OS fuzziness sets in, especially compared to the superb IS of the Canon 300 f/4 IS. Even though the Canon 300 f/4's stabilization is claimed as 2 stops...those 2 stops do not interfere with ultimate sharpness much at all (it was so sharp I never even switched it off...and I used it on the monopod about half the time...the other half hand-held).

So again, besides the difficulty getting very good sharpness above 340mm on my crop camera...The autofocus is indeed hit or miss (the main concern that might make me send the lens back and not try another one), at least on more distant objects (say more than 50 feet away). It's nothing like as accurate as the Canon 400 f/5.6 prime. Although even that Canon didn't AF very accurately in low light on very distant objects via my camera...say over 400 feet away...where again, the Sigma's problem seems to start about 50 to 80 feet away. Not a huge deal for small bird photography...more an issue for large distant birding...however, keep in mind I've not really used this lens in "good light" that is a big factor with focus accuracy as well. But as of now, I do attribute the problem either to the lens's lack of fine control over its focusing lens array by its AF motors...or to a lack of control of my camera's AF system over the lens's electronics and motors...or both. Or...for all I know, the way those elements are suspended on their rails, may be a factor. At distances near infinity, where literally you would move the focus ring a fraction of a millimeter to affect subtle changes to the plane of focus...focus accuracy can usually get very tricky (in my experience and opinion). I admit my camera's less-than-ideal AF sensor and system, are certainly in play here.

My AFMA seems to have no effect on this Sigma, even at plus or minus 20...which is extremely odd and disturbing, but I'll keep experimenting with it. I'm not even sure adjusting it would help anyway. It achieves what it thinks is focus more than fast enough for doesn't seem to move slowly (like, for instance, the Canon 85mm f/1.2L's autofocus!). I admit I haven't tried it in servo mode yet, so that could suddenly slow things down. Anyway, as for the single shot mode, I'm guessing (from my memory) the Sigma is not a lot slower than the Canon 400 f/5.6 prime...but it's quite a bit slower than the 300 f/4's autofocus. (Again, my camera's ability was in play here, besides the faster aperture and more light from the f/4).

I also plan to try the Sigma on my cousin's 5D3. If his AF nails it a lot more often than mine (very hard to believe it would not)...I may just keep the Sigma 120-400...Because I feel it will work much better on a full frame camera with larger pixels and better AF, than on my crop camera. And I do want to buy a full frame sometime in the next 6 months to a year. The extra $500 to $800 I saved by buying this lens over the Canon zooms (or the Canon 300 f/4) (the Canon 100-400 is long overdue for a version 2 update anyway)...will help fund my purchase of a full frame camera. I think I'll wind up keeping my good old 50D, though. Used prices have fallen to around $450...but 4 years and many many shots later, I still don't really want to part with it. The only reason I might, is if the 7D falls to $750 or so, after its replacement comes out. That may not even at $950 or so, I think I will pass.

I will probably post more comments here as I discover for myself, more about this much maligned, often over-looked Sigma telephoto zoom.


Photographer & Graphic Designer
Nice review.

But I don't see many positives. Whats the point of buying a lens if in the areas you want it to perform - AF, Sharpness and IS aren't particularly great and are detriment to the image.

I understand the saving money bit but I would rather spend more and get a better performing lens. Its cheaper for a reason. if your making money which it sounds like you are then why not get something better and more reliable...

But then again the 50Ds AF isnt amazing either. It may perform better on a 5DMKIII but also the FF sensor will make the lenses problems more pronounced as your crop camera is using the best part of the glass. So I would say it will be even more disappointing on FF.

Ive never liked the Sigma lenses. Ive had two, both of the front elements fell out. Canon lenses are just better and more reliable IMO.

This lens doesn't carry sigmas EX label either, sigma hasn't rated this lens to its highest class. Aimed more toward the advanced amateur not the protog. So really its not surprising it doesn't match the quality of the L glass. Suppose if your on a budget then its ok. Is the 5.6 really 5.6 tho? A lot of sigma lenses are more like 6.3 at the long end and fool the camera to 5.6 for focus.


Kodak Brownie!
Jul 19, 2011
I think one has to choose lenses very carefully. I believe that owning perhaps fewer carefully chosen lenses of great quality is the way to go. I own a Sigma 50mm f/1.4. Great lens...very happy with it. I would also consider the new 35mm f/1.4...looks like a real winner..(looking forward to what the next Art Line lens will be), but, after all I have read..I would not buy a Sigma Zoom.... I would save my money and get a lens that really performs that I could truly create images with that would excite me and others.


Apr 24, 2012
Sigma lenses are quite good. I also had the first generation of the 17-70mm and it had nothing to envy the Canon 15-85 for.

That said, the 120-400 is the lowest line of their supertele zooms. The best one would be 50-500 (affectionately called Bigma), by many preferred to Canon's own 100-400 L for having longer reach and better bokeh.


EOS 5D Mark IV
Feb 1, 2013
Thank you all for your input! As I said, I frankly don't see its performance that far behind the Canon 100-400, based on the tests I've seen online, and on the images. Really the main thing that hobbles the sharpness is the OS. (And the OS really is 4 stops...where Canon's 100-400's is only 2). Kind of seems like some of you skipped to only the criticisms of the lens, and forgot the positive aspects.

As I said, the 50-500 didn't look any sharper in the tests and photos I have seen online. It also costs $1500, weighs 6 pounds, is not f/5.6 at 400mm...I could go on.

As for the 120-400 not actually being f/5.6...I don't see why that would be? It has the same proportions and front element size as the unless you think that one is also not f/5.6 (along with the Canon 400 f/5.6 prime)...I don't really see why it wouldn't be f/5.6?? In fact, that kind of comment seems like some kind of silly snobbish slam on Sigma, based on rumor rather than fact.

In any case, at this time, no, my budget won't allow for spending $1600 on a lens, and then another $2200 on a full frame body (preferably that's with a 24-105...especially it won't if I decide to get a 5D3 with 24-105, rather than a 6D).'s not better to just wait and save up for some huge expensive lens. Not at all. If I need one of those, I rent one. And no, I am not making money from my wildlife photography, do any of you?

The Canon 100-400 just is not worth the money to me. If I had loads of disposable income, I would just collect the latest supertele lenses like some of you, but I can't.

As for the 50D's AF being not all that great...maybe it's not, but it works pretty well considering its age. I doubt the 60D's works any better. Even the mighty 5D3's system is lacking, compared to the 1DX.