Re: HP5, Delta films and reciprocity

Yes, you take the metered time, raise it to the 1.51 power, and then
multiply it by .91. Shannon posted that the time raised to the 1.48 power
was given by an ilford technician, so that might be better.

John
----- Original Message -----
From: "ragowaring" <ragowaring@btinternet.com>
To: <pinhole-discussion@pinhole.com>
Sent: Saturday, July 20, 2002 10:12 PM
Subject: Re: [pinhole-discussion] HP5, Delta films and reciprocity

> on 20/7/02 12:11 pm, John Yeo at jonnieo@thegrid.net wrote:
>
> I use the formula, y=.91x^1.51, where x is the metered time and y is the
> corrected time. It approximates the reciprocity pretty closely, and has
> worked for me for exposures up to 2 hours on FP4+, which shares the same
> reciprocity failure as HP5+. I've always processed normally, with pmk
> pyro.
>
> John
>
>
> This is fantastic John.
>
> Please excuse my ignorance but does the little arrow after the x mean
raised
> to the power of?
>
> Alexis
>
>
>
>
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Received on Sun Jul 21 07:26:26 2002