20D Autofocus

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Donald Gray - 08 Dec 2005 08:49 GMT

Canon 20D with 2.0.3 Firmware
EFS18-55mm lens (Cheap but sharp enough for now.)
EF 70-200 f/4 L (Very sharp)
When I use manual fucussing the results are sharp.

Query on what controls the auto focussing:

I am having problems with Auto focus. Reading the NG, I think it may
be 'backfocus syndrome.' Is this a problem inside the lens or is it
a problem associated with the camera?

IE: should the lens go to Canon or the camera?

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Pete D - 08 Dec 2005 10:28 GMT

Test it to see where the focus actually, don't just guess.

http://www.photo.net/learn/focustest/

> Canon 20D with 2.0.3 Firmware
> EFS18-55mm lens (Cheap but sharp enough for now.)
[quoted text clipped - 8 lines]
>
> IE: should the lens go to Canon or the camera?

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Donald Gray - 08 Dec 2005 19:30 GMT

>Test it to see where the focus actually, don't just guess.
>
>http://www.photo.net/learn/focustest/

No I did not guess.

The question is: Is it the lens at fault or the camera?

>> Canon 20D with 2.0.3 Firmware
>> EFS18-55mm lens (Cheap but sharp enough for now.)
[quoted text clipped - 8 lines]
>>
>> IE: should the lens go to Canon or the camera?

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Donald Gray - 08 Dec 2005 19:47 GMT

>Test it to see where the focus actually, don't just guess.
>
>http://www.photo.net/learn/focustest/

Thanks for the link - I have only glance at it but I shall read with
interest (And learn). The problem I have experienced is the auto focus
on 70-200 is not spot on but when I manual focus, the image is sharp,
very sharp.

I have not yet determined if it is forward or backward. It looks OOF
in the view finder.

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Randall Ainsworth - 08 Dec 2005 16:03 GMT

> Query on what controls the auto focussing:
>
> I am having problems with Auto focus. Reading the NG, I think it may
> be 'backfocus syndrome.' Is this a problem inside the lens or is it
> a problem associated with the camera?

Turn off all the focus points except for one.

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Donald Gray - 08 Dec 2005 19:31 GMT

>> Query on what controls the auto focussing:
>>
[quoted text clipped - 3 lines]
>
>Turn off all the focus points except for one.

I have already done gone down that route but the question remains; is
it a lens fault or a camera fault?

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Charles Schuler - 08 Dec 2005 21:50 GMT

>>> Query on what controls the auto focussing:
>>>
[quoted text clipped - 6 lines]
> I have already done gone down that route but the question remains; is
> it a lens fault or a camera fault?

There is no way for us to answer that question. It could be either ... it
could be both.

In fact, if you contact Canon, they will ask you to take or ship both items
to a repair center.

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