Canon 20D Backfocus Issue?

Started Dec 24, 2004 | Discussions thread
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HDLSparky
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Canon 20D Backfocus Issue?
Dec 24, 2004

Good morning.

I 'm wondering what other opinions may be out there, but I seem to be experiencing slight backfocus with the 20D. I have also tested 5 other demos from local shops and they, too, demonstrate slight backfocus using centre AF, no matter what lens I use. 17-85 f/4-5.6, 24-70 f/2.8, 70-200 f/2.8 - all backfocus slightly. Try this: print a page showing a row of vertical numbers/text, place the page on a table and from about 1 metre away at about 45 degrees (or whatever) zoom into 85mm and focus on a specific number - take a picture and then look at the result. Even at f5.6 (with the EFS 17-85 f4-5.6), I find the 20D is showing a slight backfocus. I get the same percentage of backfocus using the 70-200 f/2.8 at about 5 metres away. I can consistantly achieve better focus by tweaking the manual focus ring ever so slightly after AF has done it's job and voilla... perfect focus. I already exchanged one body, but I have the same problem; so to exchange this one does not appear to be the solution as other the 20D's appear to demonstrate the same problem. I sent some images to Canon and explained the problem and they recommended sending my 3-week old camera in for service! Has anybody else experienced this problem? It is subtle, but it's there. This, coupled with the fact that I can achieve perfect focus manually indicates to me there may be a problem... or is it that I'm expecting too much from a $CDN 2700 camera set-up? (not). The problem is very systematic, so if the focus is consistently out by the same amount, I'm inclined to think that it should be capable of acheiving perfect focus just as systematically. Perhaps it can be alieviated by a simple tweak to the firmware. Before I send it back... I would like to get some of your opinions?

Thanks for reading,

HDLSparky

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