Canon 17-40

[Rose]

Am thinking of buying a Canon EF 17-40mm f/4L USM lens for my 5D MKII. Anyone got one and care to share their thoughts ? I have two uses in mind - (i) indoors with flash, as I get asked to cover official events at work (ministerial events, policy launches, seminars etc); and (ii) outdoor landscapes where my 24-105 doesn't quite give me enough of a wide angle. I'd love a 16-35mm f/2.8 L lens of course but my budget won't stretch to that ! Will the f/4 lens give me a shallow enough DOF for indoor events ?

Thanks, Rose

[Mike Farley]

I am not sure how how much of an issue it is with the 5D MkII, but there is a problem with edges when using the original 5D and this lens. Digital sensors work best when light strikes them at the perpendicular. With a wide angle lens, the light falls on the sensor at a more acute angle and this results in lower definition. Stopping down helps, as does increasing the focal length, both of which go against your aims of having a wider view and minimising depth of field. It is not an issue with film as the angle of light does not matter fro that medium.

The attached image shows the effect with the lens mounted on the original 5D and was taken specifically to test the camera and lens combination. The focus is on the central part of the hedge and the front of the bay window behind it. Whilst it might not be readily apparent in a small, low resolution image, the hedge and planter on the left are not particularly sharp in the orginal. I would not pay too much attention to the bricks of the house, as these are quite a long way behind the point of focus. The Raw file was processed in Canon DPP and no additional sharpening was applied.

I believe that some of the same issues apply to the 16-35, although they do not seem to be quite so severe.

Most flash guns will only cover a maximum of 24 mm on full frame, so you will need some kind of diffuser to spread the light, although this will weaken its power of course.

A depth of field calculator will give an idea of how much DOF you will have at 17 mm and f/4.

Notwithstanding any of the above, the lens does get good reviews, although there is some softening beyond 35 mm, which would probaly not trouble you too much given the intended use.

Possibly the best option would be to borrow or hire the lens and try it out before making a purchase.

[Simon Clarkson]

I take most of my photos with the 17-40 on a 5Dmk2 body. I have no issues with it or its sharpness. Infact its a stunning lens... I also own the 24-105 L which has never come out since having the 17-40.

I dont use flash so I cant comment there..

[Rose]

Thanks Mike - & Simon interesting that you hardly use your 24-105 now ? This has been my default carry-around lens from the day I bought it. Guess it depends on your photographic interests of course. I often pair it with the 100-400 when I go away and that combination covers most things - but I am hankering for a bit more wide angle, hence the 17-40. I miss the sort of shots I used to get with my 40D and Sigma 10-20.