EF-S 10-22mm Review

The EF-S f/3.5-4.5 10-22mm lens is Canon's wide angle lens for crop body (7D, 50D, T2i, etc) cameras. When using this lens on a crop body (It is unable to be mounted a full frame body) the effective focal length is 16-35, similar to other wide angle lenses. If you have a crop body camera, one of your first impulses is to go out and buy this lens. (It was mine) While this is a good lens, remember that you cannot mount this to a full frame sensor. Not even 6 months after I bought this lens I bought a 5DMKII, which rendered this lens obsolete. It also is not the highest quality wide angle lens. It has good distortion correction and the horizon is always straight, but overall sharpness at most f/stops, save the small sweet spot, and especially the corners is not that great. That said, it is still a solid lens and if used correctly can do wonderful things, considering how hard it is to go ultra wide on a crop body.

First and foremost, Let's look at image quality all the way zoomed out at 10mm, for this focal length is why most people will be interested in this lens. Overall, sharpness at this focal length is good, but not great, or even very good. I mounted the lens to an EOS 30D, set it for 160 ISO, then mounted it to a tripod, and then utilized mirror lockup and used a cable release. This way, we can be sure only the lens could affect image quality and not motion of the camera/user. (For the sharpest images, always use a tripod with mirror lockup and a cable release. You will be shocked to see the difference between that and handholding your camera.) These are 300 pixel cut-outs at 100% magnification. Go ahead and download this to your computer and open them up at 200% or more to see the difference easily. As you can see, f/3.5 is not as sharp as f/5, 8, or 11. Then after f/11, f/16 and f/22 start to degrade visually. the latter is due to diffraction in which light bends like a wave through a small opening. I can't tell you anymore than that unless we delve into quantum mechanics and magic. At the larger apertures like f/3.5, the image becomes soft because of limitations on lens design called aberrations. From using this lens, I can say f/8-f/11 is probably the sharpest stop to be shooting on. If you can use that f/stop, get it on a tripod and use a low ISO (which should not be a problem because of the tripod) you will be ok. Many people will be using this lens for many different things, so why don't you look at these sample XXXXXXXX images and see for yourself. Download them and drop them into your favorite pixel editor and take a look at 200% magnification or greater.

One of the biggest issues with super wide angle lenses are horizon distortions, chromatic aberration, and corner softness. Some lenses have a habit of bending the (normally) straight horizon and make it seem like the you were drunk (were you?)when you took the image. This lens does a good job of straightening that bad boy out. In regards to chromatic aberration, you can see for yourself in the above examples. they are the purple and cyan colors on the edges of lines in your photo. They are small, but can be a problem at larger apertures. They are definitely noticeable at larger apertures around the corners on this lens. lastly we arrive at corner softness. This is a big problem with all but the most high quality wide angle lenses, and this lens suffers from it like most. You will see quite easily at larger apertures the corners of the image (these are 500 pixel cutouts from the bottom left of the full image) that the image is extremely blurred. Not until f/8 do we approach acceptable levels of corner softness. It only becomes "sharp" at f/11 or higher. You can also download this if you want to see it even closer.

Zoomed in at 22mm, we see improvement in the angular resolution (sharpness) of the image at almost all f/stops. Lens aberrations are not as noticeable when zoomed in and the largest available f/stop, 4.5, is noticeably sharper than the largest at 10mm. But, do you see the problem we have here? The largest f/stop at 22mm is f/4.5, while at 10mm it is f/3.5. This makes a big difference as that is quite a jump in sharpness, as most lenses have dramatically sharper images 1-2 stops up from the largest, this one included. The lens is pretty sharp at all f/stops up to f/11, but then diffraction rears its ugly double head of wave-particle duality. As you can see, at f/22 the image is again very soft. Check out all the images taken at this focal length in this gallery.

Remember: to even get this level of sharpness, always at least use a tripod and low (200 or less) ISO, if not also using a shutter release and mirror lockup. If you don't have a shutter release, use your self timer. I would not recommend hand holding this lens on any camera aside from ones with very good low light images (a 7D) because you have to shoot at f/8-f/11 on the wide end and if you aren't in ideal conditions it will be hard to get that without pushing your ISO up. My 30D is worthless past 640 ISO, but my 5DMKII looks like it's on low ISO at 1250. These differences in images because of aberration, diffraction, corner softness, and other black magic only make a difference if you are blowing these images up large (like more than 18 inches on the longest side) or enjoy looking at pictures only at 400% magnification and sitting 2 inches from your monitor. (like me) If you are just taking snapshots, getting a family portrait, or just don't give a !@#$, then at least this article will put these thoughts in the back of your mind, because now you know, and knowing is half the battle.