Sigma lens/10d focus problem-new everyting?

[jro727]

I currently shoot with a Sigma 28-70 2.8 and 70-200 2.8 lens on my 10d. The 28 to 70 worked great on my film camera but on my 10d it seems to prefer to focus on any hi contrast item in the background as opposed to the intended subject. Unfortunately the camera locks on and everything looks good in the view finder, but things are different when I get home and view the images on my computer. I set the camera to only use the middle focus point, fill the view finder with only the subject and then recompose to take the shot. Many times I still get really nice backgrounds. This technique is way to slow anyway. I need a system that works. The 70-200 seems to work fine.



I am going to buy a 20d. Will this problem go away do to better focusing technology?



If I buy a new lens, what should I buy? I shoot a lot of indoor events ( parties, meetings) so low light performance important (I do use flash). Most of the work is on a volunteer basis so cost is a factor too.



17-40L I suppose this lens takes great images due to being an L, but seems like it would be way to slow for indoor work.



17-85is Nice broad range zoom, but does image stabilization really make up for slow speed?



18-55usm kit lens Cheep with nice range, but still slow and many on this forum complain of image quality – looks cheep too.



Sigma 18-50 2.8 No hsm motor but constant 2.8 aperture is fast. Image quality? Camera compatibility?



Sigma 17-35 2.8-4 At what end of the zoom is the aperture 2.8 and which is 4.0. Designed for digital but works on all canon bodies.



Any others to consider?



Thanks for the help!!

[CyberDyneSystems]

How do you have the 10D AF set up?

I think this should be addressed before you buy more stuff,.

Select a single focus point,. forget about the default setting that autoselects any one of 7 AF points,.

set the 10D's custom function 4 to 1 and use the * button to focus,. keep the camera set to AI servo and single focus point.

I have used the Sigma 70-200mm EX HSM extensively for indoor event photography in low light with no flash.. and it was allways nothing short of perfect as a performer.


Lets try and get the existing problem sirted before buying new cameras and lenses..

[RichardtheSane]

I am going to buy a 20d. Will this problem go away do to better focusing technology?

Are you going to buy a 20D because of this problem or for other reasons?

As CDS said it does seem to be the camera setup rather than the lens with your AF problem, centre point only is the way to go!

As a sidenote, if you are photographing indoor subjects that move (Sports, clubs, people etc) then the IS on 18-85 will be of no use whatsoever. IS can make up for camera shake at low shutter speeds but of your subject is moving it will still be blurred.

[jro727]

I have the camera set to use only the middle focus point. I have been using one shot focus, but if the subject is standing on a stage that should work.


Thank you again for your help!

[CyberDyneSystems]

Hmm...

O-kay we've eliminated the most common error,. ei multi focus point issues..

Is the problem with one lens are both?
Is it consistant?

[jro727]

It dosen't happen with every exposure, but it happens often with the 28-70. I don't think it happens with the 70-200, but I don't use it much and not inside where there are more distractions to acheiving good focus. Im going to go expeirment with the short lense now.


This wasn't the only reason for looking at new equipment though. 20d is supposed to be much better in speed at start up as well as continuouse shooting, focus is supposed to more accurate, exposure with flash is supposed to be much better, and other things too.

[CyberDyneSystems]

Well there is no question that 20D will be an improvement over the 10D on a lot of levels,. maybe if you are thinking of upgrading anyways... it just might solve your problem as well..

[Faz]

Have you considered it simply a compatibility problem? My Fathers 28-300 Sigma worked fine with an EOS50E for a long time. Upon purchasing an EOS30 he experienced all maner of problems. The lens was returned to Sigma(UK) at their request who re-chipped it gratis.

I'm experiencing similar problems with my 28-300 which I used with an EOS55 but returns random errors on the 350D. Suffice to say it to is going back to Sigma this week, although they now charge £5 for the re-chip.

-=Faz=-

[robertwgross]

You might want to run a "ruler test" on the suspect lens.

---Bob Gross---