Re: Tonal inversion (was (Gum) Tonal scale)

Joe, et. al.,

Your absolutely right, in fact I would add that every things (conditions,
variables, parameters or whatever) in play in a test like this will
influence the result in some way, may be it will be a very small influence
not to say an insignificant one but it will.

Yves

PS. Many of you use from time to time acronyms I think there called, like
here "IIRC" below. Would there be some place I could go to find out what
they mean if this exist???

----- Original Message -----
From: "Joe Smigiel" <jsmigiel@kvcc.edu>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, December 03, 2005 1:05 PM
Subject: Re: Tonal inversion (was (Gum) Tonal scale)

> Yves, et. al.,
>
> I just realized this effect is probably also related to specific
> pigments. (This would also support what Tom has observed IIRC, and
> perhaps also to Chris' observation regarding pH.) The reversal effect
> appeared when using bone black as the pigment but not cobalt violet.
> Each was given the same exposure which presumably would lead to similar
> heating of the test wedge (assuming the integrator is working correctly
> on the exposure unit). Since the bone black reversed and the cobalt
> violet didn't, something else must be contributing to or causing the
> effect.
>
> You are correct in that it may be very difficult to isolate the exact
> cause of the effect without introducing some other variable. I
> certainly don't have the means to do so.
>
> Still, it appears I have overexposed the bone black test by roughly
> 3.5-4 stops so I'll run a test at a much shorter and more normal
> exposure to see if the reversal effect dissappears at that level.
>
> Joe
> ---
>
> >>> gauvreau-yves@sympatico.ca 12/03/05 12:10 PM >>>
> Joe,
>
> This may well be the way to check this idea out but as you say it may
> introduce something else in the process. I think it would be somewhat
> complicated to verify this, with a high degree of certainty in practice.
>
> In my own test, this happened to me as well and as soon as I reduce
> exposure
> a bit it didn't happen. This makes me believe that there could be
> somekind
> of threshold involved but again this is all very speculative on my part.
> Maybe someday I'll have the time and the money to investigate crazy idea
> like this one.
>
> Thanks
> Yves
>
>
> ----- Original Message -----
> From: "Joe Smigiel" <jsmigiel@kvcc.edu>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Saturday, December 03, 2005 11:44 AM
> Subject: Re: Tonal inversion (was (Gum) Tonal scale)
>
>
> > >>> gauvreau-yves@sympatico.ca 12/03/05 11:06 AM >>>
> > >>... I think it could be caused by heat...<<
> >
> > I agree. This seems to be plausible explanation for the effect. I'll
> > run a couple more tests reducing exposures or perhaps doing
> intermittent
> > ones to keep the negative (test wedge) from overheating and see if
> that
> > has any impact (although I might be introducing some sort of weird
> > intermittency effect by doing so).
> >
> > Joe
>
Received on Sat Dec 3 12:51:15 2005