From: Sam Wells (email suppressed)
Date: Fri Mar 09 2007 - 06:00:24 PST
Hi, it's likely you're loosing the light more in the camera's
viewfinder system than the transmission loss in the zoom lens altho
there will be some there. (diminishes as you stop down) The 1 stop
figure might be a good starting point to figure the loss.
On Mar 9, 2007, at 12:54 AM, Jim Carlile wrote:
> But your bigger problem when using an external meter to determine
> the exposure is that the f/stop value of a zoom lens will not
> correspond to that of the meter reading. In other words, the glass
> elements of a zoom lens will soak up light, so that the f/5.6 of
> your camera's meter reading will not be an accurate setting. There
> are two solutions to this:
>
> 1) figure out through experimentation how much your lens is
> generally off compared to the meter (it's probably about a stop),
> and then manually compensate for this all the time, always
> adjusting for the film speed difference, or
>
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