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Terry Lovejoy | profile | all galleries >> DSLR's For Astrophotography - Tech Notes >> The 300D filter Modification >> Modified 300D and daylight Photography >> Adjusting AF tree view | thumbnails | slideshow

Adjusting AF

The replacement of the standard Canon IRcut/AA filter with the Baader high transmission IR/UV cut filter caused the focal plane to move forward. This was because the Baader filter is about 70% the thickness of the standard filter. Anticipating this the existing shims under the CMOS were removed during the filter replacement which also moved the CMOS 0.2mm forward.

The removal of the shims was still not enough to fully correct Autofocus, but by adjusting the AF screw at the rear of the shutter compartment autofocus is now spot on.

Please note that some people have reported that the screw cannot be turned and is locked. I will investigate this further....
Autofocus Fixed!
Autofocus Fixed!
andreas bock 20-Apr-2006 19:09
Hi.
How exactly did you do this?
I found your article more or less by chance while searching for autofokus problems, since the canon service insists that my camera is alright while i have a frontfokus of 50 cm at an range of 3,5 meters with all lenses..............
so I want to do it myself
Terry Lovejoy 19-Dec-2005 20:19
ruzsa,

Its 1mm square.
ruzsa jános 17-Dec-2005 20:05
Tell me please, which key do I need for the autofocus screw? is it a square type or hex?
Which size
Art Morrison 27-Oct-2004 23:36
Hi Terry:

I so appreciate your website and that there are people like you who can perform mods and improve equipment. We do have something in common - we both like to take things apart. I'm just not as good at putting them back together as you are. So, is there anything you can tell me about adjusting the AF screw on the 300D? Such as where it is, how much dissasembly is required (I am not doing the IR filter mod, just want to adjust the autofocus.) I am just trying to see if this is something I can attempt.

Thanks so much in Advance.
- clear skies

Art Morrison
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