Help with AE Prism and Aperture Use

[wil_ussery]

Just purchased a used Mamiya 645 Pro TL and downloaded the manual, but it's not

clear how to properly use the camera with the FE401 Prism. I am using an F2.8

80mm Manual lense and I need some guidance on how to use this camera in

aperture priority mode. I have the lense set to A and the exposure dial set to

A and the FE401 set to Auto A-S.

 

Do I manually change the F-Stop on the lense to something that will allow a

hand holdable image and the exposure time will automatically change within the

finder area? What are the steps for Manual exposure Photography?

 

I can not find a manual for the FE401, so if anyone can provide a link it would

be greatly appreciated.

[dan_mcclain]

I have the Mamiya Pro and the FE401 prism. Yes, you manually change the lens aperture ring and the prism picks the correct shutter speed. If the prism tells you that it is going to use a slow shutter speed, open up the aperture until the prism tells you that it is using a shutter speed suitable for your focal length and stability. Of course if you absolutely need the picture and would rather have it underexposed than blurry you can force the body to use a certain shutter speed regardless of what shutter speed the prism recommends.

[wil_ussery]

Dan, thanks for the response. There is a slide switch on the FE401 Prism Finder right above the eyepiece that blocks the view when you're looking through the finder. What is the purpose of this switch?

[dougmiles]

Wil, light entering the eyepiece can have an effect on the meter cell in the prism. With your eye mashed against the eyepiece, this is not much of a problem, but with the camera freestanding on a tripod, the auto exposure could be affected by light entering the viewfinder from the eyepiece. The eyepiece shade blocks this unwanted light.

[wil_ussery]

Got it. Thanks Doug.

[neil_griffin2]

hi I am new to the forum and had trouble with the ae prism too. What I found out about the settings are av is averageing metering, sp is spot metering, and the a-s will let the camera choose between the two automatic. The a setting on the lets you focus and meter at full aperture. On my 645 super there are 2 auto settings, a red circle and a red square, the circle lets the camera meter what ever it sees and the square is ae lock mode, ie; take a reading from agray card and keep the shutter button half way pressed will retain the original gray card reading. You can also increase the shutter speed + or - 3 stops with the other dial on the prism. Aperture is chosen manually hope this helps. Neil