It's all geometry. I don't think you need to worry about this unless you
allow enough shift, rise or fall so that the lens moves beyond the edge of
the tunnel (note that you can get more shift by using swing on both front
and back standards, see a good view camera technique book). If your tube is
smaller than the amount of shift you allow, then you need a clear line from
the lens to the edge of your tube to the edge of the film. The worse case
is with the widest lens you allow with the max shift in the corners of the
film.
Oops, I forgot about rear swing. Rear swing will cause problems even
without shift. You just need to draw some pictures giving max swing and
shift with the shortest lens you want to use (at infinity the distance
between front and rear standards is aprox the focal length of the lens,
closer focus uses more distance between front and rear standards). Shorter
lenses generally need less swing and tilt and allow less shift (smaller
coverage) so this may be all more theoritical than a real problem, but a few
drawings should make this more clear.
Having used cameras with rotating backs vs reversable backs (ones you can
take off to swap from horizontal to vertical), I much prefer the smaller,
lighter and simpler camera you get with a reversable back to the rotating
back. Having some tube arrangement at the back other than the flat metal
ones I've used is going to be even more awkard, especially since this makes
the camera thicker and harder to use with short lenses.
John Sparks
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Bradley Small
Sent: Wednesday, January 24, 2001 10:27 AM
To: [EMAIL PROTECTED]
Subject: Re: [Cameramakers] rotating back
Wayde --
I am not sure we have addressed it. I am talking about the back not the
lense and bellows area. When I create this tunnel between where the rear of
the bellows ends and the film plane begins, will I not risk interfering with
the flow of light?
-- Bradley
---------- Original Message ----------------------------------
From: "J. Wayde Allen" <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
Date: Wed, 24 Jan 2001 09:21:49 -0700 (MST)
>> The question I have is with size. At what point does a vignetting
>> problem occur?
>
>I think we've kind of already answered this one.
>
>- Wayde
> ([EMAIL PROTECTED])
>
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