RE: [APML] 4x5 astrocamera (again?)

["Loke Tan" <tan@cox.net>]

I have a 4x5 camera from Planettown which I got from Hutech a while ago. For
some reason everyone who builds these cameras would restrict the light path
by placing an 80-100mm diameter tube in front of the 4x5 plate. I thought it
was such a waste. So I had my friend machine a body for this camera so that
the entire 4x5 film can be illuminated. However, this was the least of the
problems. Most large format lenses or astrographs have severe light fall off
at the edges, even the ones made for 8x10. You can improve the illumination
if you stop them down but they already start at f/5.6 or slower. Stopping
these lenses down really slows down the light gathering capability to the
point of being unuseable. The other problem which has already been noted is
the total lack of good astro color film at these sizes. So if you want
really good work you are forced to do tricolor with hypered Tech Pan (which
is the best B&W). But hypered TP is slow and if you are already stopping
down to f/5.6 or slower the exposures would be extremely long, not to
mention having to do 3 of them to get a color image. I have come to the
conclusion that tricolor TP are made for Schmidt cameras <g>.


You can see the camera before we got it annodized at:
http://starryscapes.com/tmp/101_0182-72.jpg
http://starryscapes.com/tmp/101_0181-72.jpg

The lens in front of the camera is a 210mm f/5.6 Rodenstock Apo Sironar W.
It was designed for 8x10 or larger.



Loke




> -----Original Message-----
> From: astro-photo-bounces@seds.org
> [mailto:astro-photo-bounces@seds.org]On Behalf Of Steve Walters
> Sent: Thursday, May 06, 2004 5:04 AM
> To: Discussion of Film Astrophotography
> Subject: Re: [APML] 4x5 astrocamera (again?)
>
>
> Well, with a 2" attachment point, you won't be getting any where close to
> covering 4x5 film. It won't show much more than 35 mm film.
>
> I don't shoot 4x5, there are some folks on the list that do, but
> isn't E200
> available in 4x5 sheets?
>
> Steve...
> www.StarryNights.us
>
>
> ----- Original Message -----
> From: "Jeff Crilly" <jlcapml@sbcglobal.net>
> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> Sent: Thursday, May 06, 2004 4:33 AM
> Subject: [APML] 4x5 astrocamera (again?)
>
>
> > I've been considering alternatives (less cost?) to medium format
> > and came across the Sky Scientific Astrocamera Model C45.
> >
> > http://www.skyscientific.com/prod02.htm
> >
> > Any comments?  (private if need be?)
> >
> > An alternative (I'm sure you're all familiar with) is ..
> > http://schmidling.netfirms.com/cam.htm
> >
> > The downside, I've read, is film choice.
> > This may be the showstopper.
> >
> > jeff
> >
> >
> >
> > _______________________________________________
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> > Astro-Photo@seds.org
> > http://seds.org/mailman/listinfo/astro-photo
> >
>
>
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