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06-12-2016, 11:58 PM   #1
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Pentax MF half-frame camera with possible issue

I have a Pentax MF half-frame camera, which was intended for endoscopy. It is pretty much based on the Pentax ME, but with a few key differences. The main difference is that it is a half-frame camera, meaning it takes portrait-orientation photos on the film, and can take about 72 of them on a 36-exposure roll. (I am mostly giving this as background for people who are not familiar with it, and are interested.)

Some photos are here:

It is similar to the MF-1, shown here, but that camera is full-frame:

I would love to get a manual for it, but I haven't been able to find one. Does anyone know anything more specifically about it?

The reason I am posting is that the camera seems to have a problem, but I am not sure if it is actually working the way it is supposed to, and that way is is different from a normal Pentax. A lens on the camera set to the largest aperture will behave in the normal open-aperture manner, but when you advance the film and cock the shutter, the aperture closes down about two stops from maximum, if you have the lens set to any f-stop smaller than that. (The diaphragm actuator of the camera moves a little bit.) I am not sure if this is how the camera is supposed to work, or if it needs repair. I suspect it is a malfunction, because if you stop the lens down two stops, then click the shutter, you can see that it gets a little smaller -- that is, the two-stops it was closed down doesn't seem to be an actual two stops. However, the lens intended for use with it has a pretty small aperture, so maybe it doesn't work the expected way with a normal lens, because it was never intended to be used with a normal lens. But since I have no documentation on this camera, or even a description of how another one works, it is not clear.

Anyone have any experience or insight on this?



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aperture, camera, film, half-frame, lens, mf, mf half-frame camera, pentax, pentax mf half-frame, shutter
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