Re: Opacity of digital negative substrates, was Re: Gum a la Sam Wang

Hi Sandy,
     This is good to know. The Apollo which I am using is really cheapy,
and very thin compared to Pictorico, which seems thicker in mls and has a
somewhat of a milky (?) coating on it. I'll check it out and see how it
relates to Pictorico. Thanx.
Chris
----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Sunday, November 23, 2003 10:22 AM
Subject: Opacity of digital negative substrates, was Re: Gum a la Sam Wang

>
> Chris,
>
> As you know there are many substrates being used for digital
> negatives but Pictorico is perhaps the most common. If you read a
> plain piece of Pictorico with a densitometer in UV mode you will find
> that it measures about log 0.15 or slightly higher. The UV reading of
> most film substrates, by comparison, will read about log 0.05. In
> other words Pictorico is less transparent to UV than film, not more.
> Other substrates I have seen appear to be thinner and would probably
> have less opacity.
>
> Sandy
>
>
>
>
>
>
> >This is interesting; I think I'll take a neg into school and measure it
on
> >the densitometer, but for sure the transparency substrate is pretty darn
> >flimsy compared to film.
> >
> >Question: in the Epson 2200 box there is a little thing (scientific,
no?)
> >where you can raise the gamma; does anyone do that when making negs?
Does
> >it do anything?
> >Chris
> >
> ><Judy said, large cut>I've always found that digital negs on paper or
other
> >NON-FILM material
> >take about half or 2/3 the exposure of negs on film, all other things (eg
> >emulsion & mix) being equal. I concluded that the difference is due, not
> >to difference in contrast and density of the film negs v. digital negs,
> >since the densitometer finds them comparable-- I develop lith film for
gum
> >to a contrast range of about 0.9, & print out digital negs at about the
> >same range.
> >
> >My assumption has been that the substrate for the digital negs is more
> >transparent to UV than film is, that is, it transmits UV more completely.
> >And somewhere in distant memory I hear a "voice" on this list saying the
> >very same thing.
>
>
Received on Sun Nov 23 10:06:55 2003