Autofocus

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Gargoyle - 25 Mar 2006 11:06 GMT

Does the autofocus mechanism on digital cameras work bu using sound waves or
by calculating focus/sharpness via the CCD/detector?

I ask because I was wondering if it is possible to shoot pictures through
windows, say at birds sitting on trees, and suchlike.

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Mark Dunn - 25 Mar 2006 11:41 GMT

By measuring contrast. IIRC there was an SX-70 which used ultrasound but
it's a collector's item now.

> Does the autofocus mechanism on digital cameras work bu using sound waves or
> by calculating focus/sharpness via the CCD/detector?
>
> I ask because I was wondering if it is possible to shoot pictures through
> windows, say at birds sitting on trees, and suchlike.

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Gargoyle - 25 Mar 2006 12:02 GMT

Thanks Mark, that's what I hoped.

>By measuring contrast. IIRC there was an SX-70 which used ultrasound but
>it's a collector's item now.
[quoted text clipped - 4 lines]
>> I ask because I was wondering if it is possible to shoot pictures through
>> windows, say at birds sitting on trees, and suchlike.

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Alan Clifford - 25 Mar 2006 14:00 GMT

G> I ask because I was wondering if it is possible to shoot pictures through
G> windows, say at birds sitting on trees, and suchlike.
G>
G>

You do have to be careful that the camera does not focus on the window as
in this failed picture:

http://www.clifford.ac/photo/2006/Courmayeur.February/tn/dscn0633.jpg.index.html

Signature

Alan

( If replying by mail, please note that all "sardines" are canned.
There is also a password autoresponder but, unless this a very
old message, a "tuna" will swim right through. )

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Mark Dunn - 25 Mar 2006 15:13 GMT

Yes, mind it doesn't focus on a bit of dirt or something.

> G> I ask because I was wondering if it is possible to shoot pictures through
> G> windows, say at birds sitting on trees, and suchlike.
[quoted text clipped - 3 lines]
> You do have to be careful that the camera does not focus on the window as
> in this failed picture:

http://www.clifford.ac/photo/2006/Courmayeur.February/tn/dscn0633.jpg.index.html

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