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Nelson Mandela Bridge at night in the City of Johannesburg. South Africa is still the most beautiful country on earth @cityofjohannesburg @awesomesouthafrica @justjozi #awesomesouthafrica #johannesburg #jozi #gauteng #braamfontein #desupredesphotos ——-> #canon5d #canoneos5dmarkiii #f18 #iso400 #1/5 #0ev #32mm #CanonEF24-105f4Lis (at Nelson Mandela Bridge)

Nikon F3 by Y0$HlMl on Flickr.

Adjusting Exposure on a Mamiya 645 1000S PDs Prism Finder

Forward:

I figured I’d do a little write-up on this since I’m sure there are other folks out there with these handsome 1970’s pieces of artillery. The PD and PDs finders are generally pretty reliable, no moving parts, more modern light sensor, LED readouts (-2EV to +2EV with 0EV in green), and can even override the shutter speed on the body itself.

Anyhoo, my particular piece of 1970’s engineering was consistantly reading 2 stops out. Bizarre. My trick originally was just to set the film speed two stops higher. My normal jam is 100 or 400 speed film, so 400 became 1600, 100 became 400.

That started to piss me off however, so out came the tools.

Disassembly:

Disassembling the PDs finder is a bit of a nuisance. There’s four screws on the outside that are easy enough to find, but there are two up front beneath the Mamiya 645 logo under the leatherette, pry the outside corners off slowly and the two screws are easy to find; no need to pull all the leatherette off. The plastic logo cap falls straight off.

The finder release button is tricky, it’s got a little black metal cap in the centre of the silver coloured knob; pry that out with a sharp knife and unscrew the retaining screw. Contrary to comments I’ve seen on line this screw is NOT reverse thread. Then just unscrew the finder release knob. The screw is just to keep the knob from backing out.

The film speed and shutter speed knob are easy. Before getting carried away set your PDs finder shutter speed to 1000/second, just trust me on this. Shutter speed use a sharp knife or thin flathead to pry the silver ringed cap out. Don’t pick at the leatherette, work the outside of the silver ring. Film speed is a flat plastic cap inset with leatherette on top. Pick at the corner with a knife, the leatherette might lift slightly but the cap will come with it. After that it’s all Phillips head screws.

Gently pull the cover off, the finder release button will catch slightly, but just push it in slightly with your finger or a screwdriver.

This is what the insides look like.

Now, your finder might be out for different reasons than mine were. Do the normal and check all the wires for bad solder joints, poor connections, etc. Mine was none of those things.

Calibration:

On the board there are a tonne of little rotary pot switches. The one on the far right concerned me slightly in that it was set all the way to one side. The way these switches normally work is to make adjustments +/-, thus it would make sense you would start them all at the middle, let’s just say 0 degrees, and then adjust +/- to get where you want to be.

Not that it made any bloody difference, but the one on the far right I set back to the middle. It didn’t help; but it didn’t hurt.

The one that did work however was the one on the top left near the white wires (the same white wires that you see coming out of the film speed selector). I adjusted this back and forth delicately until it matched both my Konica Hexar RF and my Hasselblad XPan.

Reverse all the steps to jam the damn thing back together and you SHOULD be good. Notice above that I had the finder attached without the top cover: this is useful for calibration.

Now all’s left is to put some film through it and make sure I didn’t break something else (like shutter speed communication to the body) during the job. Fun.

By Richard Eldred for http://reldred.com. Do not repost without linking back or remove my copyright. I can spot my shit writing style from a mile away and I’m half decent with a sword.