joel lederer (lederer@netvision.net.il)
Thu, 18 Feb 1999 19:10:00 +0200
Joao Ribeiro wrote:
> Hi,
>
> How can I determine the speed of an emulsion?
> I am preparing some silver gelatin emulsion and I'd like to know its
> speed.
> I guess that I can read the lux amount in my enlarger with my photometer
> and them find out by testing strips the minimum time to get the darkest
> black but how do I calculate the emulsion speed?
> TIA
> Joao
Hey Joao,
If I was doing that test I would start with the "sunny f/16 rule". For
Example, if a subject in bright sunlight's shadow tones regester properly
at a 15th of a second at F/16 than your film speed is EI 15. Of course the
film's spectral sensitivity will also affect things. Maybe you should
photograph different coloured subjects to check this too.
It occured to me now that you might be refering to a printing emulsion
and not a camera film as I assumed.
Okay.
Joel Lederer
This archive was generated by hypermail 2.0b3 on Sat Nov 06 1999 - 10:06:51