Re: large format ortho

Hi Gord,

Just to clarify it, how do you pre flash these filmes ? I mean, what light
source, how long exposure, etc. Thanks,

Ric.

----- Original Message -----
From: "Gordon J. Holtslander" <holtsg@duke.usask.ca>
To: <pinhole-discussion@pinhole.com>
Sent: Friday, November 01, 2002 3:32 PM
Subject: Re: [pinhole-discussion] large format ortho

> Hi:
>
> I use 8x10 ortho to make big negatives. I mostly print cyanotype though.
> The key is using a very low contrast developer.
>
> People have had success using a highly diluted print developer - such as
> dektol, selectol sprint etc. diluted (10:1 to 30:1).
>
> The ASA of the film is around 6 with these developers.
>
> I find these are still too contrasty with the ortho film I use (kpgraphics
> CGP)
>
> A very good low contrast developer formulated specifically for producing
> low contrast negatives from ortho film is Dave Soemarko's LC-1 developer
>
> http://members.aol.com/fotodave/Articles/LC-1.html
>
> This developer is not commerically made - you must mix it yourself.
>
> By varying the dilution and mix its possible to control the contrast
> effectively.
>
> LC-1 does result in a significant speed loss though - film processed in
> LC-1 has an ASA of 1.
>
> This does become an issue with very large format cameras, if your pinhole
> is small, the f stop is so small that the expsosure time can stretch to
> hours.
>
> You might try seeing how large of a pinhole you can tolerate (and its
> fuzziness) before you start shooting 16 x 20
>
> I think an XTOL ascorbic acid based developer at a low pH seems to work
> better
>
> See Mytol http://www.jackspcs.com/mytol.htm
>
> Chemical Amount Units
>
>
> Distilled Water 750 ml
> Sodium Sulfite 60 g
> Sodium Metaborate 4 g
> Sodium Ascorbate 13 g
> Phenidone 0.15 g
> Sodium Metabisulfite 3 g
> Distilled water to make 1000 ml
>
> This formula mixed without the alkali agent (Sodium Metaborate) may work
better.
>
> I also find that pre-flashing the film at an exposure just less than
> something that would fog the film extends the range and sensitivity of
> the film.
>
> Testing with a Stouffer step tablet I'm able to get an 18 step negative.
> Using a similar developer to Mytol and preflashing the film.
>
> Gord
>
> On Fri, 1 Nov 2002, Tim Midkiff wrote:
>
> > Hello all,
> >
> > Does anyone have firsthand experience using large format ortho film,
> > 16x20, in camera for gum prints? I've been doing a few the hard way,
> > making the first exposure, then making a high density neg then making
> > the gum prints. any ideas or suggestions, etc would be greatly
> > welcomed!!!
> >
> > thanks, tim
> >
> >
> >
> >
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>
> ---------------------------------------------------------
> Gordon J. Holtslander Dept. of Biology
> holtsg@duke.usask.ca 112 Science Place
> http://duke.usask.ca/~holtsg University of Saskatchewan
> Tel (306) 966-4433 Saskatoon, Saskatchewan
> Fax (306) 966-4461 Canada S7N 5E2
> ---------------------------------------------------------
>
>
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Received on Sat Nov 2 02:10:39 2002