P3D FED batteries

[jeremy.hinton@xxxxxxxxx]

Phil,

I didn't reply earlier as I didn't have my FEDs at work with me :).

I have two FEDs - an original basic model, and an M.

The original has a mercury cell - which my local photo shop has no 
trouble replacing. Its a 625. Just under 3pounds i think. I measured 
the voltage last night as 1.6v (!). 
(cell was replaced in January and has been in the camera ever since)
I know it should be less, but it wasn't under drain. Typically, the 
camera underexposes, so I set the ASA window to 50 for a 100 ASA film.
The cell is quite large, with an extra flange on it which I haven't 
seen on any other sort of cell. When it starts to fail, it overexposes 
dramatically.

My FEDM uses a silver cell (measured at 1.5v, which is closer to what 
it should be.) When this one failed, the camera _underexposed_!.
(I emailed P3D in confusion at the time)
(cell was replaced in January and has been in the camera ever since).
I thought all FEDM's had silver cells? The cell doesn't have the extra 
flange, and is similar to my normal camera batteries. It has a plastic 
insert (a short piece of tube) to make it fit snugly into the battery 
compartment which is the same as that in the FEDbasic.

When I had a chance - (with no film in either camera), I compared them 
with each other and with an SLR light meter - sat in dining room and 
adjusted the light (dimmer switch!) until the FEDM _just_ fired on 
auto. Assumed that this was F2.8 1/30. Compared with SLR it was about 
right.
FEDbasic wouldn't fire until _way_ more light. I adjusted them before 
the Swiss balloon trip, and the resulting exposures were pretty good - 
although I used them on Manual quite a bit (assuming 1/30, set the 
aperture on the scale).

I've hardly used them since, and some of the questions this raises 
should really be sorted - but I'm afriad it's pretty far down my 
priority list (moving house etc)


Jeremy Hinton


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