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Old Jul 4, 2005, 7:11 PM   #1
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Hi all...

Can anyone help me with this? I shoot with a Canon EOS20D and with a Sigma 28-300mm F3.5 - 6.3... When my lens is pointing in an area of bright sunlight I have problems with my AF... It hunts & hunts & the other day the camera froze. I had to remove the battery & then replace to get the camera working again. I heard that maybe the lens has to be chipped!! Is it FREE or does it cost. Any help will be greatly recieved....

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Old Jul 5, 2005, 2:39 PM   #2
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If it is an older Sigma lens, it may. If so, Sigma does it at no charge, assuming you have proof of purchase. The only cost will be shipping. If you are having this problem with a recent vintage Sigma, however, you may have a different problem--a defective lens or camera. Sorting that out may be a trick if you don't have a friend with a 20D to test it for you.

Good luck with it.

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Old Jul 10, 2005, 7:59 AM   #3
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When shooting into the sky or bright /Highcontrast areas the camera might not find something to focus on. So it will hunt trying to find something to focus on.

Try focusing on something that is a little darker or with less brightness. once the camera has focus hold the the shutter button at the halfway point and recompose your shot to where you want it.

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Old Jul 10, 2005, 8:56 AM   #4
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I agree with bluwing, I think it is more a problem with your subject than your equipment.
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Old Jul 26, 2005, 11:55 AM   #5
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Hi all... Had it chipped by Sigma... What a difference... If I now point at a set of net curtains the focus locks on fast where before I had to rely on my manual focus... I only had that problem with the Sigma lens and found all my Canon lenses worked fine...
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Old Aug 9, 2005, 6:48 AM   #6
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How do you go about getting one chipped if you didn't buy it new? I bought mine second hand from a reputable camera shop, but not locally.

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Old Aug 9, 2005, 9:07 AM   #7
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Question about your posting.... when your 20D and Sigma lense froze up, did you have a "00" in the apeture readout? I have a 20D w/ a Sigma 24-70/f2.8 and that is happening to me also. The two ways I can fix it is 1) dismount and remount the lense, or 2) remove and replace battery. It sounds like the same issue. I'm going to send my lense back to Sigma to get it re-chipped. thanks.

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Old Aug 9, 2005, 9:55 AM   #8
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Yip its on the list.
Sometimes. Unfortunately certain third-party lenses not built by Canon, notably many older Sigma lenses, will not work correctly on some newer EOS camera bodies like the Elan 7/EOS 30/33 and the digital EOS 10D. The most common symptom is the mirror flipping up and then the camera freezing when you try to take a photo. You then have to switch the camera off to unlock it. The only solution to this problem is to see if Sigma will upgrade the lens for you. If they still have inventory of the control chip they apparently will happily do so for free.

The only third-party maker of EF-compatible lenses with no major compatibility problems so far is Tamron. Some people have suggested that this is because Tamron have licensed official lens protocol data from Canon, but Canon USA's Chuck Westfall has stated repeatedly in public fora that Canon have never licensed their lens mount protocol to any other manufacturer. So Tamron have either been very lucky or very clever in their reverse-engineering of the Canon lens system. They seem to be a reasonably safe bet right now for compatibility, given their track record, but it's impossible to predict future developments in this regard.

The following Sigma lenses require upgrading for compatibility with newer EOS cameras, according to Sigma:

24-70mm 3.5-5.6 aspherical UC
28-80mm 3.5-5.6 mini zoom macro aspherical
28-80mm 3.5-5.6 mini zoom macro aspherical HF
28-80mm 3.5-5.6 mini zoom macro II aspherical
28-105mm 2.8-4 aspherical
28-105mm 3.8-5.6 UC-III aspherical IF
28-135mm 3.8-5.6 aspherical IF macro
28-200mm 3.5-5.6 DL aspherical IF hyperzoom macro
28-300mm 3.5-6.3 DL aspherical IF hyperzoom
70-210mm 4-5.6 UC-II
70-300mm 4-5.6 APO macro super
70-300mm 4-5.6 DL macro super
100-300mm 4.5-6.7 DL
135-400mm 4.5-5.6 APO aspherical RF
170-500mm 5-6.3 APO aspherical RF
8mm 4 EX circular fisheye
15mm 2.8 EX diagonal fisheye
24mm 2.8
28mm 1.8 II aspherical
50mm 2.8 EX macro
105mm 2.8 EX macro
300mm 4 APO tele macro
400mm 5.6 APO tele macro
500mm 4.5 APO
500mm 7.2 APO
800mm 5.6 APO
28-70mm 2.8-4 UC
28-105mm 4-5.6 UC
28-105mm 4-5.6 UC-II
70-210mm 3.5-4.5 APO macro
28-200mm 3.8-5.6 aspherical UC

Buy Canon, its anL of a better Lens :blah:
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Old Aug 9, 2005, 11:36 AM   #9
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Lboy is correct, many of the older Sigma lenses did have problems.

Either stay with L (for some reason they seem to work on Canons)
or with the Sigma EX line, none of them have had any problems either.

Only annoyance I have with Tamron is their lack of an Ultrasonic drive, so they focus slow.

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