[rollei_list] Re: OT: Replacing Mercury Cells in a Nikon F
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Mon, 19 May 2008 17:34:26 -0700
----- Original Message -----
From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Saturday, May 03, 2008 6:20 PM
Subject: [rollei_list] OT: Replacing Mercury Cells in a
Nikon F
I've finally been able to compare mercury and zinc-air
cells. I found that the mercury cells in my Luna-Pro were
still good. So, I made tests using both mercury cells and
zinc-air cells in both the Luna-Pro and in the Nikon F. I
used a Sekonic Studio De Luxe as a control since it is a
selenium cell meter and will make both incident and
reflected light measurements. Past experience has shown
close agreement between the Sekonic and Luna-Pro for both
types of measurement. The Nikon is a through the lens
reflected light meter.
The results in short are that both the Nikon and
Luna-Pro read the same with both types of cells within my
ability to control the conditions. The Sekonic ageed with
both. Since the Nikon is the only one of these meters that
has a known field of view (approximately that of the lens) I
was careful to use a target with a large area and uniform
light. This is a house accross the street from me recently
painted a sort of off-white. I also checked by reading
another house with multiple colors. I also made incident
readings with the Sekonic and Luna-Pro. These were
identical. There were slight differences in the reflected
light readings but they were less than a stop. The Nikon
fell in with both meters.
The Zinc-Air cells in the Nikon have been unsealed for
about two weeks.
It is too short a time to know what the life of the
zinc-air cells will be. Previous experience with mercury
cells shows the life in either the Luna-Pro or Nikon to be
several years.
My conclusion is that zinc-air cells with a simple
adaptor made of a rubber O-ring is sufficient to replace
mercury cells in these two devices.
Since the Nikon has a contact on the side which must
touch the case of the cell I wrapped a small amount of
aluminum foil on the upper O-ring to make connection with
both this contact and the body of the cell. This seems to
work.
The battery check indication on both Nikon and Luna-Pro
reads exactly the same with either type of cell.
It is possible that some extension of cell life could be
gotten for the zinc-air cells by plugging up some of the
ventillation holes in the cell. I've not tried this. I want
to see what sort of life these cells have as they are.
The shelf life of the cells if kept sealed is supposed
to be at least three years.
The zinc-air cells I used are Size 675, sold for use in
hearing aids. I got mine at a Radio Shack store. They came
in a package of eight cells and were pretty cheap. The
O-rings are a standard size and came from an assortment I
bought at a hardware store so long ago that I have no idea
which store or how much they cost. I think they are No.10
size.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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