The worst image quality a lens delivers is generally in the extreme corners of the frame and zoom lens corners frequently have a level of mushiness to them. The good news is that the corners of 16-35 f/4L IS images are very impressive – prime-like.
Comparison Image Capture and Processing Details
All images on this page were captured on a pair of Canon EOS 5D Mark III DSLRs simultaneously triggered remotely. Two cameras were used due to unstable lighting caused by clouds and haze in the sky, insuring that same aperture images were captured at exactly the same time and that differences were not falsely created due to lighting changes. Both cameras were positioned within 2" of each other and were focused on the identical subject, placing the plane of sharp focus line with the flowers in the lower right corner of the frame.
Images were processed in Digital Photo Pro using the Standard Picture Style with a sharpness setting of "2" (low).
All crops shown below are from the absolute bottom right of the frame. I could have picked any of the four corners to compare and the results would be similar. I chose the lower right because the yellow flowers were nice to work with and this area of the frame had some depth to show/tolerate some field curvature.
I opted to not perfectly align the comparison crops so that the absolute corners would be shown. I trust that you will still easily recognize the differences. As vignetting is also most noticeable in the corners, it can play a role in the brightness of the crops shown.
The Canon EF 17-40mm f/4L USM Lens is not included in this comparison, but it is a very relevant alternative to the 16-35 f/4L IS. The 17-40 L performs similarly to or slightly worse than the 16-35 f/2.8L II.
Canon EF 16-35mm f/4L IS USM Lens Compared to the Canon EF 16-35mm f/2.8L II USM Lens
Ultra-wide angle zoom lenses are often most needed for and most used at their widest focal length as general purpose lenses typically cover the 24mm and longer focal lengths, so perhaps most important is the 16mm comparison. Use the links below the image to show the image for selected lens and aperture setting. As you mouse between the results, watch the difference between the results.
The 16-35 f/2.8L II is a very good lens, but the 16-35 f/4L IS is clearly better at comparable apertures. The 16-35 L II shows slightly more CA (Chromatic Aberration) and even with diffraction evening out the results slightly at f/11, the 16-35 f/4L IS holds an edge in sharpness/contrast.
Moving on to 24mm, the 16-35 f/4L IS takes a bigger lead in the results.
Even at f/11, the 16-35 has some corner mushiness remaining.
The comparisons at 35mm are similar to those at 24mm with the 16-35 f/2.8L II being soft even deeper into the frame.
The green spruce tree shown deeper into the frame should be well within the depth of field at f/8 from this moderately long subject difference and the 16-35 f/4L IS shows that to be true. That subject is not rendered sharp by the 16-35 f/2.8L II.
Looking at images as a whole, the 16-35 f/2.8L II and the 16-35 f/4L IS compete much more strongly in the center of the frame, but the 16-35 f/4L IS rules the mid and outer portions of the image circle.
Canon EF 16-35mm f/4L IS USM Lens Compared to the Zeiss 15mm f/2.8 Distagon T* ZE Lens
One is a high-end, very-high-priced prime and the other is a mid-priced zoom. You think you know which one wins that competition, right? You may be surprised to see how close the zoom compares to the prime.
15mm vs. 16mm
The focal length is different, but many can make either of these lengths work for their ultra-wide needs.
I still love my Zeiss 15, but ... it may not get as much love with the 16-35 f/4L IS joining my kit.
Not recognizable in this comparison is that the Zeiss prime has less distortion (though it is not completely distortion-free).
Back to the Canon EF 16-35mm f/4L IS USM Lens Review.