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FORUMS Cameras, Lenses & Accessories Canon Lenses 
Thread started 07 Dec 2006 (Thursday) 02:36
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Focus tracking with 20D and large aperture?

88 posts
Joined Jul 2006
Location: Finland
Dec 07, 2006 02:36 |  #1


I'd like to know whether I should suspect the dreaded mis-focusing here.
Yesterday I was shooting some dogs playing with 20D and 85mm f1.8. Because it was rather dark I often used apertures 2.2-2.5.

However, when checking the results from my pc I got the feeling that about 80% of the shots were off-focus -mostly behind if they were coming towards me. Of course, the dogs were running fast, but I had thought that 85mm f1.8 could follow them more accurately.

So, would you say this just because of shallow DOF combined with 20D shutter delay and lesser-than-1D-focusing? (I've never experienced this with 70-200f4)

BTW, can 20D focus predictively so that the shutter delay is taken along? (ie. focusing-shutter pressed-still focusing-click-done -- NOT focusing-shutter pressed-focusing stopped-click...)

Thanks for any help..!

Sample here:

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Larger version at http://picasaweb.googl​ …photo#500551956​7358215026 (external link)

All shots are taken with the same set...

Extra batteries / Rocket blower / Small tripod :rolleyes:

Senior Member
335 posts
Likes: 1
Joined Oct 2006
Location: West of Scotland
Dec 07, 2006 09:13 |  #2

Looking at that picture in a little more detail, it looks like you have motion blur all round . . . non of the ground is in perfect focus, so i wouldn't be blaming the lens too much in that one.

Looking at #9, if anything, it looks like its slightly focussed to the front rather than the rear.

Overall, at the resolutions of the images, i think they look alright. Or more to the point, I dont think they look bad ( if you get what i mean )

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Focus tracking with 20D and large aperture?
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