maxshirley.net: photography - Comparison of the Canon 17-40 f/4 L and 18-55 f/3.5-5.6

Comparison of the Canon 17-40 f/4 L and 18-55 f/3.5-5.6

Pictured above is a Canon 20D with 17-40 f/4 L lens attached. Thanks to anselpixel for the shot. Note that the following tests were taken without the lens hood.

UPDATE: I no longer have access to the 17-40, so this will never be finished!

Disclaimer: I have not finished this page... it is just a starter. Also, this is obviously not a professional test rig. You should only look at these examples to compare the two lenses to eachother rather than to some other benchmark.

The most striking difference is the vicious light fall-off or vignetting that occurs at wide apertures on the 18-55. You can see this in the third table which shows 100% crops of the upper right corner.

An interesting find that I haven't quite figured out yet is that even though the camera, tripod and the subject stayed perfectly still, obviously the 35mm focal length produces completely different photos. The focal lengths were within 1mm or so.

Interestingly, at dead center, the 18-55 seems to keep up with the 17-40.

Never use f/25 or f/29 on the 18-55 unless you have to for some reason (I can't think why you might need to). The softness is unbelievable.

With the 18-55, try to keep it at least f/7.1 or preferrably more like f/8 or above to avoid the severe light fall-off and edge softness.

Also, keep in mind that this is merely one optical test. The 17-40 is built like a Mercedes and the 18-55 like a Kia. They'll both get you places and under certain conditions, the Kia is almost as good as the Mercedes, but in the end - the Mercedes is still clearly the preferrable car to drive - no matter what.