When Sigma announced this lens I really wasn’t at all interested as I thought it would just be a budget lens with lots of compromises leading to mediocre image quality and poor handling like I experienced with some of the earlier models of third party tele-zooms. However when reviews started coming up I read a couple that suggested that this lens actually had decent image quality and I started looking into it more closely.

I do mostly bird photography and my main lens is the Canon EF 500mm f/4L US USM, which does a great job. However, when I am out there are often times when 500mm is just too much focal length and over the years I have missed plenty of shots as a result. My thought was to buy the Canon 100-400mm f/4.5-5.6L IS USM II which I have had a good deal of experience with and is an all around fantastic lens. The story would have been over right there except this new Sigma lens was supposed to have comparable image quality to the Canon lens that costs 2.5x as much. Another bonus with the Sigma is that it is a pound lighter in weight than the Canon (about 1 pound lighter). In addition Sigma sells the USB dock that allows the AF to be adjusted more precisely by the end user (me) than can be done with the Canon. I can also adjust the Sigma AF for my Canon SL1 which doesn’t have the AFMA feature which is a benefit over the Canon.

The Canon has the advantage of a closer minimum focusing distance, 97.5cm vs 1600 cm for the Sigma. Interestingly the max magnification between the two lenses isn’t that big, 0.31x for the Canon vs 0.26x for the Sigma. This can be a significant difference for my use as I often like to photograph smaller insects. The Canon also has a tripod collar that makes working from a tripod easier which the Sigma lacks.

With all that in mind I went ahead and ordered the Sigma to see if it will do the job for me. After spending several days taking pictures with it on a Canon EOS 70D and EOS 7D mk2 the way I plan to use it moving forward I have the following thoughts.

The image quality of the Sigma is excellent, definitely a match for the Canon. I find that the Sigma can deliver excellent contrast and detail even at its widest apertures. The only reason to stop down that I can find is when more depth of field is desired. Definitely a big thumbs up for the Sigma here.

Both lenses have stabilizers to help when using them hand-held. My experience so far is that the Canon’s IS is significantly more effective than the Sigma’s OS (at least when considering these two models). I find it is often difficult to tell that OS is active when looking through the viewfinder while it is easy to tell when the Canon’s IS is engaged. What’s more important is that in my far from rigorous testing, the Canon does actually deliver a higher percentage of sharp shots and lower shutter speeds, at least as low as 1/30 second or so. I didn’t really do any testing below that speed. The difference doesn’t seem to be huge but it is there.

The next obvious difference between the two lenses in actual use is that the AF speed on the Canon is noticeably faster. The Sigma isn’t what I would call slow but the Canon is obviously faster. Also, the Canon is less prone to hunting making it easier to catch action/flight shots with the Canon. This isn’t to suggest that the Sigma can’t be successfully used for these types of shots, it most certainly can.

What I found more alarming, was that when I received the Sigma I immediately needed to apply AFMA to the lens to get either of the test bodies to “consistently” give properly focused shots. I found that I needed a setting of +10 at 100mm and +14 at 400mm to get the best consistency. This is more adjustment than I have ever needed for any lens. The Canon 100-400 mk2 on the other hand needed zero AFMA to give optimum AF, though plenty of my other Canon lenses do need some AFMA for best results.

Having sorted out the AFMA settings for the Sigma, I found that