Autofocusing Canon 15mm on 10D/20D

[jkantor]

I want to know if this lens is actually usable in autofocus mode on

a 10D and 20D.

 

I have the Sigma 15mm. It is an incredibly sharp lens - but it will

not autofocus at all on my 10 and 20D cameras. (Focusing by eye is

impossible too). Instead, I have to zone focus it, which is very

slow and often leads to missed shots(at weddings). (I've used it on

3 bodies and returned it twice: once for repair and once for

replacement - same problem.) It seems to focus pretty well on my

EOS3, so maybe it's a compatibility problem.

 

What I need is a 15mm that focuses quickly and accurately in low

light on the 10D and 20D. Has anyone used the Canon 15mm - wide

open - on a 10D or 20D?

[jkantor]

And this is for action shots of people at weddings - not tripod shots of landscapes or buildings.

[mcgarity]

I haven't used the 15mm but I do own the EF-S 10-22mm. I have found that at ultra wide you actually have to work to get something thats not in focus. At 15mm the f4 hyperfocal distance is 9.8 feet. At f5.6 its 7.02 feet.

 

Unless you are extremely close to your subject, you could get excellent results by prefocusing in manual mode at the hyperfocal distance and then forget about it. I would thing that would be fast and easy.

[chrisjb]

Hi, we`ve been using a sigma 15~30 for a number of years and have no focus problems with it, though its not as sharp as the prime.have you tried it with just the centre focus point on a contrasty subject as being so wide the camera is probably just focus on the brightest object.

 

This shot taken last nite is 15~30, 1/10th sec f4.5 1600ISO handheld focus with only centre focus point on sax mouthpiece

 

Good luck<div></div>

[chrisjb]

Forgot to mention this shot was without flash and about 1/2 a stop under but focus was not aproblem, most of our reception work and restuarant pics with flash we rarely have trouble with this lens but it is prone to flare in bright daylight.

[david_kieltyka]

I only use AF with my 15mm when I want to focus on something close. Like within one meter. Otherwise I manually focus to one meter, halfway between one meter & infinity, or infinity depending on guesstimated subject distance and aperture. DOF with this lens is huge even wide open. Too huge for accurate AF beyond two meters or so.

 

-Dave-

[andrew robertson]

There is extreme shadow noise in that shot. Did you shoot JPGs? RAW files might allow

you to open up the shadows without as much noise.

[chrisjb]

Hi Andrew, the shot was in jpeg and hasn`t been adj for noise, I`ve just started using a kodak plugin called `Digital Gem professional` so should have adj before posting. Just pointing out focus was ok in such low light with AF. I think a 20D would perform better at the 1600ISO