From: Ken Sinclair (photo1@telusplanet.net)
Date: 12/17/02-11:18:42 PM Z
In one of the phot mags (Photo Techniques??)... sometime in the past year
(or so) there was and article about a photographer using a long tube (3+
feet) in front of his "box" with a pinhole as a "lens".
His results were remarkable. I would not have believed the detail he
managed to record.
Having said that, I guess I am now going to have to do a search of my boxes
of magazines and report back with the magazine and the issue.. unless
someone else has it (readily) to hand.
Ken
>> At 2:23 PM -0800 12/17/02, Shannon Stoney wrote:
>>>Katherine wrote:
>>>
>>> One interim solution I've come up with
>>>> is to fix a pinhole to a lensboard and stretch the bellows out as far as
>>>> it will go, which is around 30".
>>>
>>>That's interesting. So, in effect that makes a pinhole telephoto aperture?
>>>
>>>--shannon
>
>Sam wrote:
>>
>> No, Shannon. Not a telephoto. Just a long lens. A telephoto lens of
>> 30" focal length will physically measure maybe just 10".
>>
>> If you load your 8x10 holder with a piece of 35mm film and put it
>> behind your 12" lens, you'll get a narrow field of view, but the 12"
>> lens would not have transformed into a telephoto lens.
>
>But, what if you change the pinhole aperture to have a focal length that
>matches the bellows extension of 30"? I'm looking at the chart in Eric
>Renner's book on p. 124 where he gives different pinhole sizes for different
>focal lengths. My pinhole camera is six inches deep, takes 8x10 film and
>has an aperture of f352. That's the "correct" pinhole aperture for
>sharpness at six inches focal length. So it's wide angle and it's in focus.
>If you wanted it to be telephoto and in focus, couldn't you increase the
>bellows length to say 30" as Katherine says, and make an aperture that would
>cause the image to be in focus, ie the "correct" aperture for a 30" focal
>length? (Eric's chart would say 1.0267 mm, or f750.) Wouldn't that be like
>making a pinhole telephoto image, in the same way that my camera makes a
>wide angle image? I wonder if the image would look like a telephoto image,
>sort of, taken with a lens.
>
>--shannon
[||/\/\/\/\//\/|| Ken Sinclair RBP, FBPA.
[|| ||-| Applied Photographic Services
[|| || | Lethbridge,
[|| || | Alberta, Canada,
[|| ||-| (403) 381-1654.
[||\/\/\/\//\/\|| photo1@telusplanet.net
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