Re: Pinhole Light Meter

John Fletcher wrote:
> It does not currently cater for reciprocity failure primarily because
> the Provia F100 I use does not seem to have much. Being a film based
> parameter that would necessitate, currently, under or over stating the
> film speed you are using after taking a meter reading. Reprocity failure
> compensation would actually not be hard to program I am just worried
> that there may be hundreds of different papers / films people can use
> all with different characteristics.

If you look in Michael Covington's "Astrophotography for the Amateur"
you'll find a discussion of reciprocity failure, a formula for
adjusting exposure based on time and a film parameter, and a method
for testing film to determine the parameter.

Robert Reeves has a web page online
<http://www.robertreeves.com/filmtest.htm> that show a similar method.
This is also discussed in his book "Wide-Field Astrophotography".

-- 
Brian Reynolds                  | "It's just like flying a spaceship.
reynolds@panix.com              |  You push some buttons and see
http://www.panix.com/~reynolds/ |  what happens." -- Zapp Brannigan
NAR# 54438                      |  
_______________________________________________
Post to the list as PLAIN TEXT only - no HTML
pinhole-discussion mailing list
pinhole-discussion@spitbite.org
FAQ at http://spitbite.org/pinhole-discussion/list.html