20D with Sigma lens - Not as quick as 10D

[Croasdail]

Okay - I have gotten used to the less then quite 20D going thwack-thwack when it shoots, but two days ago at sunrise in Bryce Canyon I put on my 70-200mm f2.8 sigma HSM - and for the first time ever I had the lense go hunting... I have never had this lense do this on this on my 10D. It eventually found focus - but it was more like a 1-1000, 2-2000 - then lock... unlike when on the 10D when it is a buzzz - click and then locked - less then 1-1000. Anyone experience this too?

[robertwgross]

Dim lighting can make any lens a little slow on autofocus. What autofocus mode was the camera set for, and what was the subject?

---Bob Gross---

[ScottE]

My Sigma 105 macro lens worked fine on my D60, but completely froze the camera on my 20D when I got it. I sent it back to the distributor to have the operating chip upgraded and it works as well as it ever did now. There was no cost other than shipping to Sigma. They did the upgrade, gave the lens a good cleaning and shipped it back for no charge.

If your problem persists, check with Sigma to see if the chip needs to be upgraded.

[Croasdail]

Bob - at first I was letting the camera pick the focus point - but I changed over to center focus point. I was not using ai servo or anything like that. The subject was Bryce Canyon as sunrise which was pretty contrasty - and light was resonably good - I think I was shooting f7 or less at between 250 and 500. I started with the polerizer on - then popped it off to see if it made a difference... which it didn't. I wish I had tried my 10d to do an apples to apples comparison but had left that body back in the car.

I will be heading back into the back country again today up in the sawtooth mountains in Idaho and will try some more. It was cold that morning... perhaps that was it. who knows. Maybe it was a one time thing with colors it didn't like. I'll mess around and see what happens.

ScottE - thanks for the advice..... I have only had the lens a short time but it could have been old stock I guess - so if it does persist - of to Sigma it will go. I like the 20D... but all this is also making me appreciate my 10D more. It may not have all the bells and whistles... but it is a solid performer.

[CyberDyneSystems]

Croasdail.. I am freash out of Sigma lenses to try.. used to have quite a stable of them with my old 10D.

All I can say is that the 20D AF is noticeably faster and more accurate with my current Canon lenbses than the 10D was...

The 70-200mm f/2.8 EX HSM should not require any rechipping (no EX HSM should) they are too new for this issue to effect them.

[robertwgross]

You know, a polarizer can cost you as much as two stops of light. That might have been enough to force the camera down into the marginal-autofocus range of light.

I find sunrises to be very tricky. There are so many things going on that can each provide a challenge, and throwing them all together will cause something to fail. If nothing else, then the mere fact that the photographer can't quickly see all of the controls will make it tough.

In general, for a sunrise shot, I am aimed somewhat into the sun direction. At that angle, a polarizer won't do much (positively), but the negative effect of the light loss makes me throw it off. I find the best time to shoot a sunrise is about 30-45 minutes prior to when the sun hits the horizon. Exposures are very long then, but the color is great.

---Bob Gross---

[Croasdail]

Thanks... I learned I have a lot more to learn. Sports is so much easier. thanks for the advice. I switched back to the 10d and it behavied better. Not sure why... but now I know and work around it in the future.

[felix21685]

yeah but its still supposed to work the same if not better on your newer 20D..i wouldn just let it be...IMHO

[Mohawk]

One thing I have noticed, reading here and other such sites, is that the 20D seems to be rather finicky if using non Canon lenses. I know that my Bigma, when attached to the 20D, will hunt for focus, even in mid day lighting. All of my Canon lenses are immune to this hunting problem on the same subject. I gave up on trying to use the other guys lenses, they just don't do the job from my expierience. I keep the Bigma around more for the novelty I guess, It's a nice lens for what it is.

Mike

[jimtfoto]

One thing I have noticed, reading here and other such sites, is that the 20D seems to be rather finicky if using non Canon lenses. I know that my Bigma, when attached to the 20D, will hunt for focus, even in mid day lighting. All of my Canon lenses are immune to this hunting problem on the same subject. I gave up on trying to use the other guys lenses, they just don't do the job from my expierience. I keep the Bigma around more for the novelty I guess, It's a nice lens for what it is.

Mike

I've noticed quite the opposite. Compared to my 10D, my newly-acquired 20D seems to hunt less for focus with the Bigma.

cheers,
jim

[EOSAddict]

Interesting thread - thanks.

Also, Croasdail, ....."at sunrise in Bryce Canyon ...."

YOU LUCKY ****** ;) I am so envious. Did it 4 yrs ago and shot more slide film than was good for me. Can;t wait to go back again.

[Mohawk]

I've noticed quite the opposite. Compared to my 10D, my newly-acquired 20D seems to hunt less for focus with the Bigma.

cheers,
jim


Really! I wonder what it is with the AF on these 20D's. I had a couple of Tamron lenses that had hunting issues, amongst other things, on the 20D. I sent them back and excanged them for the "L" equivalant. No problems now.

Mike

On edit: And not to say that my Canon lenses never hunt. All lenses will occaisionally hunt, I just find that my Bigma will take a few seconds longer then say my Canon 400mm 4.5L on the same subject in mid day light. The Tamron 2.8s were the same indoors with what I would consider exceptable mid day light coming in the house. Those two did allot of hunting, to the point it was annoying.