[pure-silver] Re: Kodak vs Ilford

  • From: "Jason McPeak" <mcpeak.jason@xxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Sat, 22 Mar 2008 20:17:29 -0500

Richard K,

    I finished the roll of ADOX 100 ASA. I did several shots in the gardens
in front of my apt, a couple of the cat, etc. I got lucky, I have inherited
the GRAFLEX, but also a CHICAGO MAJESTIC tripod and head that I use with it
for it's extreme stability. I will be developing it in a few hours or so.

On 3/22/08, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>
>
> ----- Original Message -----
> From: "mail1" <mail1@xxxxxxxxxxxxxxxxx>
> To: <pure-silver@xxxxxxxxxxxxx>
>
> Sent: Friday, March 21, 2008 10:26 PM
> Subject: [pure-silver] Re: Kodak vs Ilford
>
>
>
> > Richard, Your comments on film curves verses film types is
> > excellent.
> >
> >
>    Thank you:-)
>    I didn't talk about the shoulder because most modern
> films don't really have a shoulder until they reach
> impractical densities. Most B&W films have an enormous
> overexposure latitude, six to 10 stops in many cases. This
> is not the _range_ of the film but the amount the exposure
> can be increased from the ISO exposure and still have good
> tone rendition.
>    I suppose I should define a shoulder. Just as the film
> has a low contrast area for very low exposures (the toe) it
> also looses contrast for very high exposures. At some point
> the film reaches its maximum density and will just go no
> further. The theory books will show an area of reversal for
> extremely high exposures but modern films do not seem to
> ever reach this point. As the highest densities are reached
> the contrast is reduced and this part of the curve is called
> the shoulder.
>    A shoulder can also be produced by the developer. Some
> developers just are not active enough to develop the highest
> possible densities on the film. If you look at the data
> sheets for Kodak films which show development in the
> Versamat automatic processor you will find the higher
> densities shoulder off at noticably lower densities than
> when developed in something like T-Max or even D-76.
>    It is possible to generate an artificial shoulder by
> using what is called a "compensating" developer. These are
> highly diluted or otherwise designed to have too low an
> activity to reach the highest densities. Also, development
> without agitation will result in local exhaustion. In the
> dense areas the developer reaction products build up slowing
> down development. In normal processing the agitation removes
> these reaction products and allows fresh developer to
> penetrate the emulsion. Not all developers are equally
> sucessful in stagnant development because some reaction
> products actually accelerate development rather than
> restraining it. A developer containing Metol as the sole
> development agent will exhibit compensation and also edge
> effects because the reaction products of Metol are
> restrainers. Rodinal, which is related to Metol behaves the
> same way. The reaction products of hydroquinone, OTOH, are
> accelerators and a hydroquinone developer will not show the
> same sort of effects from low agitation as one having only
> metol in it.
>     Printing negatives with very high density highlights is
> a problem. If the image is not too complex the exposure of
> different areas can be adjusted by burning and dodging. To
> do this well (so that its not obvious on the final image) is
> not too easy and requires a lot of practice.
>     Local contrast can also be reduced by the use of
> contrast masks. These can be made with a contrast higher
> than the negative so that they result in a non-linear final
> curve. Contrast masks used to be common in color printing
> especially with Cibachrome. They are not too difficult to do
> for B&W. Similar effects can be gotten from electronic image
> editing programs like Photoshop but many are not aware that
> they can be generated photographically albeit with more
> work.
>
>     A last word on film curves: I think the best explanation
> of their effect is in the older Kodak film databooks. I have
> no idea where to find these other than camera swap meets or
> dealers specializing in this kind of thing. Its possible
> some library systems may have them. The edition is not
> important because the same text was reprinted with the film
> data sheets tipped in. Its the text you want so having
> obsolete data sheets is of no consequence.
>
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
>
>
> =============================================================================================================
> To unsubscribe from this list, go to www.freelists.org and logon to your
> account (the same e-mail address and password you set-up when you
> subscribed,) and unsubscribe from there.
>



-- 
I am a leaf on the wind! Watch how I soar.
                 -Hoban "Wash" Washburn
                        (serenity movie)
-----------------------------------------------------------------------
http://mcpeak.jason.googlepages.com/home

Other related posts: