Topic: i almost hate to ask.... (Read 1773 times)

Sune Wendelboe · « **on:** August 03, 2005, 06:22:42 am »

I have the same problem with 70-200mm f/2.8L IS USM and 24-70, 100-400 too.

Sent the camera to Canon Denmark, they found nothing wrong, now I don't trust AF anymore for infinite.

The problem wasn't present in the 10D and hopefully wont be in the next body.

--Sune
www.globalphotographic.net

Jonathan Wienke · « **Reply #1 on:** August 03, 2005, 02:03:54 pm »

The reason the lens allows the focus ring to rotate past the infinity mark is to compensate for slight manufacturing variances and expansion/contraction due temperature changes.

If you rotate the focus ring past the point where true infinity focus is achieved (regardless of whether that corresponds with the infinity mark on the focus scale), whether manually or via autofocus, nothing will be in focus, and the farther past infinity you go, the more OOF everything will become. If your autofocus is consistently focusing the lens past infinity,then either the body or the lens, or both need to be sent to Canon for recalibration. If sending in the body doesn't help, send the lenses as well.

mark tipple · « **Reply #2 on:** August 03, 2005, 03:10:27 am »

hey all, after reading the last 4 page discussion about the 20D front focussing problems, hopefully mine will be simple. i'll start by saying that....

i'm a full blown rookie.

there it's out in the open. now to the problem.

on a bright sunny day, with my 20D, and 70-200 f4, it seems as though when i auto focus on an object past the infinity mark, i think it's about 10 meters for this lens, the camera (lens) cant quite make focus and focuses a little shallow.

i remember reading that the variation on the infinity mark is due to the temperature,(?) and i have to manual focus between 2 millimeters rotation with the focus ring.

without confusing us both even more, it sems from the other posts that my lens may need to be recallibrated? or is it the body?

if you need any more info i'll try to suss it out, but maybe there's an easy fix, maybe firmware or so?

thanks in advance, mark.

mark tipple · « **Reply #3 on:** August 03, 2005, 06:30:09 am »

yeah, i tried my lens on my friends 350D and worked better than mine, kinda frustrating for long shooting.

mark tipple · « **Reply #4 on:** August 04, 2005, 05:23:43 am »

yeah thats kinda what i was dreading...i'll chase them up. thanks guys.

Author Topic: i almost hate to ask.... (Read 1773 times)