Mike Kirwan wrote:
>
> Back in 2005 Sandy King published some findings on computing
> reciprocity failure and came up with the formula for corrected
> exposure time for reciprocity failure calculated using the
> tr=tc,1*(tm^1.62)+tm
>
> Does anyone remember this? Does Sandy still subscribe?
>
> I made charts for TMX, TMY, HP5 and Delta 100 and they were pretty
> accurate and was wondering if anyone had the constants for other,
> still in production, films.
I don't remember Sandy King's work, but Micheal Covington in
"Astrophotography for the Amateur" and Robert Reeves in "Wide-Field
Astrophotography" each provided formulas, and testing procedures for
determining film reciprocity failure constants.
You can find Robert Reeves' methods and (very old results) via the
Internet Archive at:
<http://replay.waybackmachine.org/20081228114031/http://www.robertreeves.com/filmtest.htm>
I can look up Micheal Covington's results (I seem to recall that he
found T-Max 100 and E200 to be the best of the films he tested), but
all the Kodak films have changed since these books were published, so
I think it would be better to do your own test.
--
Brian Reynolds | "It's just like flying a spaceship.
reynolds@xxxxxxxxx | You push some buttons and see
http://www.panix.com/~reynolds/ | what happens." -- Zapp Brannigan
NAR# 54438 |
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