I found the Wein zinc-air replacements did not work in my old Nikon Ftn but worked well in my Gossen Sixtar (Super-Pilot). Go figure.
MR-9 waistes battery power. Zinc Air cell loses its charge quickly. Silver Oxide or Alkaline do not have flat discharge curve so if recalibrate accuracy changes as battery ages.
So I would simply not power these devices and use them san power. Who needs a meter especially one that is not very accurate.
Sure glad I've got a slug of mercury batteries in the freezer. Unless they end up going bad, I've got a lifetime + supply.
Last edited by mikebarger; 03-02-2010 at 06:42 PM. Click to view previous post history.
I've used the Gossen Battery Adapter with two 1.5V Silver oxide cells in a coupla applications (Weston Ranger 9 meter, the Gossen LP), and they worked just fine. I would think they would work in most applications where two 1.35V mercury batteries are required.
Good morning, Chan Tran;
Originally Posted by Chan Tran
Sir, I cannot agree with one of your comments about the discharge characteristics of the Silver-Oxide (Ag-O) battery chemistry. The criticism about the alkaline batteries is valid, but not for the Silver-Oxide.
Of the battery types available to us today, the Silver-Oxide most closely approaches that of the old 1.35 VDC Mercury (Hg) batteries, although at a slightly higher voltage of 1.5 VDC, but the discharge curve is almost equally flat. If a recalibration is necessary (but it will not be needed in almost all cases where an adapter is used), that calibration will remain valid for the entire flat portion of the discharge curve.
Then there is the point about the forward biased Schottky Barrier Diodes in the MR-8, MR-9, and other battery adapters to provide the close equivalent to the Mercury battery voltage of 1.35 VDC, or a multiple of that. This approach is superior to the use of a voltage dropping resistor to achieve that effect, and is much more efficient. It is our most cost effective way today to work around the banning of the old Mercury batteries when used with the Silver-Oxide batteries we can buy today.
Ralph Javins, Latte Land, Washington
When they ask you; "How many Mega Pixels you got in your camera?"
just tell them; "I use activated silver bromide crystals tor my image storage media."
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unfortauntely my Yashica only seems 1/3rd of a stop under-exposed on the meter with a 1.5v battery.. can compensate, but I'd like 1 or 2 stops... seeing as ISO set on camera for metering for goes down to 25 but only up to 400.
I just bit the bullet and bought the MR-9 adapter from C.R.I.S. I've had no problems with it.
Whilst I agree with what you are saying, a bridge circuit will use a meter where the needle in the centre indicates correct exposure. I would not refer to this as 'match needle'.
Originally Posted by dr bob
If your camera's meter indicates correct exposure with a central position and the meter needle rests at that position when switched off then it is very likely that you have a bridge circuit which will tolerate voltage differences.
If your exposure is set by moving one needle (or other indicator) to match the position of the meter's needle then it is not a bridge circuit and will be affected by voltage variations. This type of circuit will also have the meter needle return to one end of its travel when switched off.
For the latter type which need 1.35 volts, I think the best solution is to use a 1.5 volt silver oxide cell and have a schottkey diode internally wired in series with the cell connections.
"People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.
I agree with Ralph. The silver batteries are about as close as you can get to a mercury battery in voltage curve. So, as long as you compensate for the voltage difference - I find that a Nikon body that originally ran mercury will read about 2/3 of a stop too high on a silver or alkaline battery - or you have the gear recalibrated and use a silver battery in either case, you'll have consistent readings for quite some time.
With respect to the MR-9 adapters, Robert Decker does not recommend them for the F Photomic FTn finder. At certain EV values, the meter uses too much current than the MR-9 can handle. He says that recalibration is the only way to go. I did this on my F FTn's meter, and have to say that the batteries in it, which are about 18 months old at least, are still fully charged and allow the meter to provide an accurate reading. The needle still deflects a little over correct exposure when I depress the battery check button.
Same with my black Nikomat FTn, which I had recalibrated about a month ago to 1.5 volts. Matches my chrome FTn which is still running a nearly new mercury PX625 (thanks mgb74, btw). All three cameras match my F2A and my FM2n. My F3, due to it having more of a spotmeter, can vary a bit compared to the rest of the bodies. The only body that I haven't compared them to is my FT2, which, prior to a week or so ago, was off a stop and had a very erratic meter. Now is overhauled and awaiting pickup.
Nikon CdS meters in manual exposure bodies typically are just center-needle meters (or in the case of the DP-2 finder, center-diode - like the FA and the F3), whereas the EL and the ELw use a match-needle system, like the later EL2, FE, FE2, FG-20, and FM3a.
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As you are probably aware David the EF is unique in that it has a self- regulating metering and should work correctly with 1.5 volt alkaline cells,http://en.wikipedia.org/wiki/Canon_EF_camera, mine works fine with these even shooting velvia 50. I'd get it checked if I was you, I've tried Wein Zinc- Air Cells but find they don't last more than a couple of months, and are very expensive
Originally Posted by David A. Goldfarb