There's no easy way to do stop-down metering with a Zuiko lens, as the DOF
button doesn't lock.
But if you're trying use a pinhole body cap, an OM2x or OM4x will both measure
the light via OTF metering and work fine.
If you've bought a precision-made pinhole, they usually come with an estimated
f/stop like f/128 or something equally crazy (similar to Large Format
apertures). You could then estimate the exposure from a hand-held meter and
bracket 1-2 stops on either side in 1/2 or 1/3 stop increments as a test to get
the right exposure for your hole. There might be some reciprocity issues to
deal with too; check the film data sheet.
Given that the scenes you'll usually be photographing with a pinhole are
usually daylight scenes, the extrapolation from a hand-held meter is usually
straightforward. For astronomical stuff, the exposure is usually determined by
a book or test, as there is too much black sky that will confuse the meter.
Microcope stuff depends on the subject.
Skip
----- Original Message ---------------
Subject: [OM] "Stopped Down" Preview Metering?
From: "Curtis P. Hedman" <Curtis.P.Hedman-1@xxxxxxxxxx>
Date: Mon, 10 Jan 2005 12:57:00 -0600
To: olympus@xxxxxxxxxx
>
>A question for the experts again....
>
>Do any of the OM series permit or support "stopped down" metering before
>the shutter is released? I have been doing some experimentation with a
>pin-holed body cap, and the Loreo PC lens in a cap, and finally figured out
>that the body cap has no provision for communicating "maximum aperture" to
>the body, so the "preview exposure metering" of the "auto" mode is
>hopelessly confused. I am assuming that the OTF metering during actual
>exposure works just fine (but haven't actually proved this with actual
>film, yet). I did note, however, that when I put one of these "caps" on my
>OM-PC and switch to "Program" mode, the viewfinder display is happy to
>estimate a shutter speed that appears to be about right for the lighting
>conditions/film speed (this is with the Loreo PC, which has two aperture
>settings - f/11 and f/22). In Auto mode the OM-PC displays the "longer than
>1 second" icon with the same setup/conditions....
>
>So I'm coming to the conclusion that I should just forget about using the
>finder display to "preview" the exposure with any of these gadgets, and
>rely on an external meter, or just fire away and let the OTF metering do
>its thing... and it would seem to me that same situation would apply if I
>use a microscope or telescope adapter - true?
>
>Any insight will be appreciated!
>
>Curt
>
>
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