Re: rodinal developer for infrared

[Kayo Matsushita <kayo@xxxxxxxxxxxxx>]

At 13:51 -0400 9/12/96, JoePaduano@xxxxxxx wrote:

>Kayo-- The information contained in Laurie's book about the #15 & #25 filte=
rs
>producing the same effect with Konica infrared is incorrect. Obviously the
>red filter will absorb more blue light ( which the film is sensitive to )
>than the #15 orange-tests with the film support this. With the red filter,
>there is more contrast overall and less with the #15, due to more shadow an=
d
>highlight detail.

Hmmm...but Konica infrared isn't sensitive to wavelengths between approx.
510nm to 640nm (green, yellow, orange). And if the orange filter cuts out
wavelengths below 520nm (green through UV) and the red filter below 640nm
(orange through UV), why would there be a difference? I'm not necessarily
disagreeing with you, Joe - I'm just curious. I wonder if the #15 filter is
not as sharp-cutting as #25 filter is. Is the test you're referring to your
own test? And if so, could you tell me more about it?

>Also, the asa chosen to
>shoot the film with has no bearing on development time with infrared films,
>as they are not given a rating. Development is by time and temp. only.

This, I don't necessarily agree. Exposure certainly affects the appropriate
development time, especially if I were to push or pull process the film.
Indeed, I was thinking maybe that's why the big difference between Russel's
and my settings for ASA and development time - I mean, either he is pushing
the film speed in effect, or mine is resulting in "pull" processing of the
film. I guess this kind of manipulation for infrared film is not as clear
nor straight-forward as for regular panchromatic film, but it's still
possible, isn't it? I remember seeing "great pushability" as one of the
characteristics of the new Ilford film.


Kayo Matsushita - kayo@xxxxxxxxxxxxx -



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Topic No. 26