Re: HP5/Rollo Pyro reciprocity

From: William Laven <wmlaven@platinotype.com>
Subject: HP5/Rollo Pyro reciprocity
Date: Thu, 18 Mar 2004 13:20:27 -0800

> Having been away from shooting for ages, I shot some HP5 for Rollo
> Pyro development today (for Pt/Pd printing) and was getting indicated
> exposures in the 5-20 second range. Using an old reciprocity chart
> for Tri-X/HC110 I gave a hefty amount of exposure to compensate for
> reciprocity failure (always my albatross) and, lo and behold, gave it
> too hefty an amount.
>
> Anyone have some suggested reciprocity exposure times for HP5?

If this exposure condition is your typical, or at least this isn't a
rare case, I'd suggest to have one more film at hand. For this
purpose, I recommend Fujifilm Acros or Kodak T-MAX 100. T-MAX 400 is
better than HP5 Plus or Tri-X, but not as good as those two. At the
metered time of 15 seconds for ASA 400, you'd have to expose for about
60 seconds with HP5 Plus. This is about the same as what you would
need with Acros anyway.

Reciprocity failure is caused by inefficiency of making latent image
and is practically independent of developer of choice.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)