Archived posting to the Leica Users Group, 1998/11/21

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: [Leica] [Fwd: Re: Testing Film Speed / California Coast Trip]
From: Nathan Wajsman <>
Date: Sat, 21 Nov 1998 21:11:54 +0100


If you have all the necessary equipment then you can be really scientific
about it, like Erwin. If not, than the only method I can think of is to take
some shots of a grey card, first at the indicated meter reading, then
bracket in both directions in 1/3 or 1/2 stop increments. Develop the film.
Then print a contact sheet with an exposure such that the perforated edges
of the film are black on the print. Take your print and compare with the
actual grey card to see which exposure matches closest. If you shot nominal
100 speed film but the closest matching shot is one where you overexposed by
1 stop, then your effective film speed is 50.

Of course, what you are really testing here is your entire process,
end-to-end: exposure, negative development, exposure in the enlarger, paper
development. So the effective film speed you arrive at will only work for
you and only so long as you keep the other process elements consistent.


Ron & Beelian Miller wrote:

> How does one test a film for its effective speed. Erwin has informed us
> test results for some film, but I'd like an idea how to go through it
> once so I know how to do it for other films?  How would you conduct such
> a test?

- --
Nathan Wajsman
Overijse, Belgium

Photography page:
Motorcycle page: