Re: extremely long exposures

Hi Guillermo

I am interested in using the reciprocity formula that you posted for Fuji
colour film too but the formula and the formula that you use in the example
are different.

(1) Corrected Time = (4.44 x Time x Time) + (1.311 x Time) - 3.55

vs. (2) Corrected Time = (4.44 x Time) + (1.311 x Time) - 3.55

Which of these is correct? I am guessing that it is the second as the first
seems to give excessively long exposure times.

Cheers and thanks.

Tim

>From: "G.Penate" <penate@home.com>
>Reply-To: pinhole-discussion@pinhole.com
>To: <pinhole-discussion@pinhole.com>
>Subject: Re: [pinhole-discussion] Re: extremely long exposures
>Date: Sat, 6 Jan 2001 19:46:45 -0500
>
>
>----- Original Message -----
>From: "Stephen Harris" <smhcine@email.com>
>To: <pinhole-discussion@pinhole.com>
>Sent: Saturday, January 06, 2001 9:54 AM
>Subject: [pinhole-discussion] Re: extremely long exposures
>
>
> > > Stephen,
> > > Tell us what film you intend to use and we may be able
>to
> > > help you.
>
> > Guillermo, I'm using Fuji 400 ASA Portra Neg in 120 roll film.
>
>Color film, eh? Unfortunately I have no experience with that kind of
>material.
>
>Let's see if this can help you, taking the exposures indicated by Fuji for
>"long exposures", if I try to find an equation that "fit" a polynomial
>curve
>joining those exposures, a little program I have came up with this:
>
>Corrected Time = (4.44 x Time x Time) + (1.311 x Time) - 3.55
>(Time should be expressed in seconds)
>
>For example for 5 minutes = 300 seconds the corrected time would be:
>
>Corrected Time = (4.44 x 300) + (1.311 x 300) - 3.55
>Corrected Time = 1722 seconds or about 28 minutes and 42 seconds
>
>Let us know if you give it a try.
>
>Guillermo
>
>
>
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Received on Sun Jan 7 06:48:17 2001