On Mon, 30 Apr 2007, Godfrey DiGiorgi wrote:
> It's odd that you would see this pattern when using Takumars
> (presumably M42 screw mount?) stopped down in Av mode. The camera
> body knows nothing at all of the lens opening in those cases and
> should be responding to the light as if the lens were wide open. At
> least in the green-button stop-down mode case, the body has stopped
> the lens down from wide open to working aperture so there's something
> going on there that could account for it.
>
> Some folks have told me that replacing the focusing screen with a
> Pentax *ist DS focusing screen solved the problem. I might give that
> a try when I get a moment. I tried switching my custom Katz Eye
> screen from the DS into the K10D but found consistent underexposure
> with FA/DA lenses so that wasn't useful to me, but perhaps the Pentax
> DS screen will act differently.
>
> Godfrey
I've reported making it worse. Of course the split-prism adds a
whole other variable at small apertures. Perhaps the angle of light going
throught the stock screen doesn't couple properly to light meter sensors?
Bottom line of course is that stop-down metering sucks.
-Cory
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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