Re: Goofy project idea

[William Chang <wchang@xxxxxxxxxxxxxx>]

VERY interesting binoculars effect :-)  Thought
I was the only one with that goofy idea.

Perhaps try a focal-plane shutter camera like Pentax 645
-- mount a Pentax 35mm extension tube inside a 645 extension
tube, somehow.  SLR and no shutter worries.  I might try it :-)

BTW are you a machinist?  I have a ton of wacko ideas
(stereo or panoramic) but no machinist experience or
tools other than a Dremel...  I'd love to learn how
to do this.

Best,
-- William (wchang@xxxxxxx  Berkeley, CA)

> 
>   I've been admiring a Pentax screwmount
> fisheye lens that is on consignment at
> a local store. It is a full frame fisheye
> rather than a circular fisheye. This
> is both good and bad. You don't get the
> "see half the world" effect of a circular
> fisheye. It is only 180 degrees of view
> across the diagonal.
> 
>   The good is that it means the image
> circle of the lens is at least 43mm
> (the diagonal of 24x36mm). So I'm thinking
> maybe it could be rigged up to produce
> a 40-some mm circular fisheye image on
> 120 film.
> 
>   The rear element of the lens is pretty
> small so you could potentially put
> a leaf shutter behind the lens and still
> project the full circle onto the film.
> 
>   My first thought is to destroy the
> non-working diacord that I have. But
> cutting far enough back to get the
> lens close enough to the film would
> ruin the bottom film spool holder.
> After a bit of thinking I decided that
> maybe a 6x6 folder type camera would
> be best. The spools are off to the side
> out of the way. And by removing the
> bellows etc it should be possible
> to get close enough to the film plane
> to get infinity focus from the screwmount
> len.
> 
>   The second aspect is the shutter.
> The shutter that came with our Tominon/
> Polaroid 127mm lenses looks like it might
> do the job. So I unscrewed the lens
> elements. The clear aperture of the shutter
> is good, but the front thread is only 40mm
> diameter or so. Pentax screwmount is 42mm.
> Darn!
> 
>   I could machine down the fisheye's M42
> threads but that's kind of drastic. I'd still
> like to use it for 35mm photos too.
> So I guess I need a bigger shutter, unless
> the lens could mount in front of the Tominon
> shutter, rather than thread into it, and still
> be able to project the full circle.
> 
>   Some of you have seen my semi-fisheye stereos
> taken with my Bronica with 75mm lens and a 0.42x
> fisheye adapter. I liked the effect but wasn't
> happy with the sharpness away from the center.
> The Pentax lens is much sharper so I think it would
> make some very interesting shift type stereo
> shots.
> 
>   So, does anyone have any ideas about a
> camera body that might work, and/or a shutter
> to place behind the fisheye lens?
> 
> Thanks - Greg
>