RE: lith film, bergger film, cyanotype

[Joachim Oppenheimer <joachim@microdsi.net>]

Please explain how a curved film plane can receive even exposure from a
point (pinhole or lens, for that matter). Each point of the film is at a
different distance from the pinhole so that the light fall-off differs
accordingly. I would appreciate your take on this. Thanks in advance,
Joachim

> -----Original Message-----
> From: Christina Z. Anderson [mailto:zphoto@montana.net]
> Sent: Wednesday, May 15, 2002 10:06 PM
> To: Alt Photo List
> Subject: lith film, bergger film, cyanotype
>
>
> Hi all!
>      I've been experimenting with different lith films in a
> pinhole camera,
> and different developers.  I have used Arista APH and APHS (no
> difference I
> can tell...) in Howard Efner's nifty 4"x10" pinhole camera, with
> an exposure
> of about 48 secs Sunny 16.  It is an f269 camera.  He made it so that the
> innards of the camera curve the film plane in a semicircle so exposure
> is even.  Fun stuff (hopefully he will manufacture said
> camera and sell it; the one he is letting me use is his prototype).
>     A couple things I've found.  One is that it sure doesn't seem
> that lith
> film experiences reciprocity failure at those long exposure times.
>      I used it at ISO 6 and 10; both work, but ISO 6 and development in
> Dektol 1:10 for 2.5 min as per someone's recommendation on this list works
> well.  at ISO 10 in Dektol 1:6 for 1.5 min it also works fine.
> Pinholes are
> now minimal without the weak acetic acid stop bath, just using water.
>      I've been testing the negs out with some old cyanotype
> solution--it is
> Mike Ware's stuff, 3 yr old, goes on a bright chartreuse green but exposes
> well and in about 5 minutes in full sun.  I tried it on kid finish Cranes
> and it was terrible; bled and washed out.  On Platinotype it is
> really nice.
> I tested the solution to make sure it was working up to snuff by comparing
> it to an old exposure neg that I had worked out 3 yr ago and it was just a
> tad lower in contrast and that is all, after sitting in my cupboard 3 yr.
>      I just got a packet of Bergger BPF 18 in the mail to test against the
> lith film and I will report back the results.  It is a continuous tone,
> ortho film.  I do not know the ISO of it--anyone on the list find
> one out in
> using this film?  John Horowy (sp) doesn't quite know either.  He
> told me to
> try it at a paper ISO so I will try it at 6, too, but it is
> expensive enough
> to not want to waste--about $2.40 an 8x10 with shipping.  Arista APH and
> APHS are, of course, pennies a sheet. Anyone have development times and in
> what, or any experience at all with this film?
> Chris
>
>
>