I recently purchased a Canon 17-40mm f4/L USM lens as a wide angle lens for my full frame Sony a7ii using a lens adapter, and I thought I would share my thoughts on it. I typically do not go into the techincal aspects in my reviews, but give more of a real world impression and performance of it.

I am mainly a landscape photographer and I wide angle lens is a much for my type of compositions. I have been using the Canon 10-22mm lens for the past 3 years or so on Canon 550D which is a crop sensor camera, so after switching to a Sony a7ii which is the full frame camera and I needed a lens that would support the sensor size.

Sample Images

I will be making comparison to the Canon 10-22mm lens through out the review as that is a good reference point for me to go from, I have also embedded multiple sample images I captured with the 17-40mm as a practical example of the type of images that can be created.

My previous Canon 10-22mm lens was the equivalent of a 16-35mm lens on a full frame sensor so there was only 2 options, either the Canon 16-35mm or the Canon 17-40mm and I ended up choosing the 17-40mm because it is considerably less expensive and its lighter and more compact while still providing the good focal range.

The 17-40mm doesn’t go quite as wide as a 16-35mm but thats not a big deal for me, and it is only slightly larger than my previous 10-22mm

I have been using the lens for just over a month now, and overall I am very pleased with it.


Icey Field Canon 17-40mm

The perspective this lens has really lends itself to giving that epic feel when shooting landscapes.

Epic Hunter Photo Canon 17-40mm

At 40mm this lens results in a decent amount of scene compression, I found this useful as I dont need to change my lens as often.

Speed

The auto-focus speed is nice, fast and accurate which isn’t exactly a high priority in landscape photography but it doesn’t hurt.

Weather Proofing

The lens is rated as being weather proofed, there is a rubber ring around the lens mount to prevent water and dust. However you need to have a UV filter attached to the front to provide a seal on the front glass element.


Forest Teepee Canon 17-40mm

The lens captures plenty of detail, with a little bit of falloff around the edges.

Sharpness

The lens is nice and sharp in the centre of the frame, the corners are noticeably softer if you examine them but its not a big deal when viewing an image as a whole.




Distortion

Compared to my Canon 10-22mm the distortion and vignetting seems to be reasonably more noticeably on the Canon 17-40mm, the corners have a distinct darkness to them but it is an easy fix in Lightroom. The distortion at 17mm is quite severe, which you would expect with an wide angle lens and it is much more subtle at 40mm.


Long Exposure Canon 17-40mmThe color reproduction makes for some great effects in bright frames.
Overall

I am really happy with this lens and it has a great wide angle focal range for landscape photography, the fact that it can go to 40mm means that it can be used as a wide general prupose lens as well which I have found useful as I dont need to swap lenses as often.

The vignetting is a little more than I am used to, but it is an easy fix in software like Lightroom.

A fairly surprising shallow depth of field can be archived with this lens at f4 and and nice sharp frame north of f8, I would recommend this lens for anyone looking for a more compact wide angle lens for a full frame camera compared to the Canon 16-35mm.


Winter Bridge Canon 17-40mm

I love the perspective this lens gives when its set to 17mm.

Foamy Shores Canon 17-40mm

Getting low to the ground can give some nice effects