[rollei_list] Re: OT: Replacing Mercury Cells in a Nikon F

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Sat, 3 May 2008 20:23:50 -0700


----- Original Message ----- From: "Eric Goldstein" <egoldste@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Saturday, May 03, 2008 8:17 PM
Subject: [rollei_list] Re: OT: Replacing Mercury Cells in a Nikon F


They are cheap but they are very unpredictable. They have a short life when activated and there have been many reports of these cells being sold from outdated stock, rendering them of little use. So the problem is you can carry lots of spares with you and still be out of luck...

Not my idea of a good solution but others seem OK with them...

There are now exact sized replacement SO cells for the 625, so if you can simply recalibrate the device for the voltage difference, this may
be a better way to go...


Eric Goldstein

Thats just the problem, you can't "recalibrate" because the error depends on the voltage and that is not constant for most types of cells. The great virtue of the mercury cell is that its voltage curve is very flat. That allows using the cell without a regulator. Regulators in general dissipate some of the energy in the cell so, if its possible to do without one its desirable. My solution is a makeshift. I have no idea how long the cells will last but the meter has a definite check point so there is a positive indication if the cell voltage changes much. This gives me a simple and cheap way to keep the TTL lightmeter in this camera going, at least for the present. I have a junk finder so I can see if there is room in it for some sort of regulator. That would allow using alkaline cells although they are not long lived compared to mercury cells either.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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