In article <33123AE8.673F@outinohio.com>, fhawk@outinohio.com says...
>Bill Brodie wrote:

>> Thanks to those who responded in this thread and via E-mail.
>> Now, a follow-up question:
>>
>> Different screens have different light-absorbing / light-transmitting
>> properties. Metering, I would guess, is based on the light that makes
>> its way through the screen. Does this mean that with each screen
>> it's necessary to downgrade (or upgrade) the film speed setting
>> depending on whether the screen transmits more (or less) light
>> than the factory-supplied screen? In other words, if I'm using 50 ASA
>> film and a screen that admits 1/3 F-stop more light, then should I
>> set the film speed on the camera to 40 ASA? If so, do screens
>> generally come with a number indicating how much compensation to perform?

>I'm assuming that you're talking about a focusing screen.... If that's the cas
>e, the
>only thing that it will change is the viewfinder---not the TTL metering. There
> should be
>no adjustment required for your film speed, etc.

Ummm, since the TTL meter (ambient light) in most SLR's (and in the one
in the original post) reads off the viewing screen, the brightness of
the screen will affect the metering accuracy (if the screen for which the
meter is calibrated is replaced with a brighter one).
Hope This Helps