Mercury battery adapters.

[kiev4a]

The older Nikon Fs with Photomic finders suffer from the same problems as other cameras of that generation. Their meters were designed to run on PX-13 and PX625 mercury batteries. And they don't make mercury batteries any more.

I did some research on alternatives. Old Pentaxes have a tolerant circuit that allows the use of a modern 1.5 volt silver battery (by using a spacer to make the battery fill the battery compartment). But Nikon circuits aren't as tolerant. They want a 1.35-volt battery -- as do some other cameras and meters.

You can buy a C.R.I.S adapter that reduces the the voltage of the silver battery and makes it fit the compatments designed for mercury cells. But the adapters cost $30 bucks each. And I have been told they don't work that well on the Nikon Photomics (although one worked great in my old Gossen Luna Pro meter).

You also can get the Wein zinc-air batteries that will work. They were designed specifically to fill the photo power void. But they are rather pricey (about $10 each here) and only last about six months.

Recently I stumbled onto www.paulbg.com/Nikon_F_meter_batteries.htm
This individual has come up with a machined brass spacer that allows the use of the 1.35-volt ZA675 zinc-air hearing aid battery that can be purchased almost anywhere for about $5 for a package of six.

It wouldn't be that difficult to make the adapters if one had a metal lathe and some machinest skills (I have neither) so I just ordered two of the adapters from the web site -- about $16 including postage. The only downside is that the seller is in England so it may be awhile before I get em.

Anyway, I'm sure there are some other folks out there with cameras made for the mercury batteries who have the same problems. I'll keep you posted on the results. If it works well, I have a friend with a metal lathe who might be able to turn the adapters out on this side of the pond.

[John Parry]

Hi Wayne,

A quick and cheap (free) alternative is to put the silver or alkaline battery in the camera. Set up a 'trusted' camera with the same lens, ASA rating etc. Set up the aperture and speed of a scene on the trusted camera. Set the same aperture and speed on the other camera, and note the deflection of the meter from the 'correct' point while viewing the same scene. Then take all your shots with the same deflection. It's also worth comparing the two cameras at different ASA ratings. With luck the deflection will be the same throughout the range.

I've found this method to be pretty linear, but on some cameras the meter circuits are too sensitive, and the 10% voltage difference takes the meter off-scale, which is no use at all.

Note that the deflection direction is counter-intuitive (to me anyway). You have to open the lens more with a silver battery to get the correct reading.

Also, if you find there is little or no deflection across the range, then the camera probably has a bridge or regulator circuit and you can use silver batteries anyway.

Regards - John

[greyhoundman]

You can also put a #9 o-ring around the 675 zinc-air battery. My wife's Oly RC runs fine on them.

[kiev4a]

The trouble with the O ring on the Photomic is at least one of the two batteries has to have the "collar" on it to make proper contact with the chamber cap. I figured for the price difference might as well get two collars.

John, according to some things I have read the Nikon finder is one that falls into the sensitive area and a little variation can't be tolerated. Wish it was like the Pentax which will a silver 1.5 volt battery (with a collar around it) and the circuitry will automatically adjust for the voltage difference.

[kiev4a]

Followup on this discussion:

Yesterday I was talking to my friend Doug. Doug is a computer engineer who in his younger days worked at a camera store. In that capacity he was able to collect just about every Nikon F model every made and nearly every lens-- all in near mint condition. Doug knows Nikons. Anyway, I was telling Doug about the battery adapters I was ordering so I could use the cheap zinc-air hearing aid batteries. He said "just use the 1.5 silver batteries that are the right size for the camera. Only picky slide shooters might notice the difference in readings and the meters are old enough they probably aren't that accurate anyway."

So I picked up a couple of the 1.5 silver batteries of the proper dimensions. Then I checked out the camera meter readings against my Gossen Luna Pro. Almost exactly the same with Kodak Gold 200--less than half a stop all the way from bright sunshine to deep shadows. Since I shoot color and black and white negative that has a lot of latitude, it's no factor at all.

Glad I only spent $16 on those adapters I ordered from England and Really glad I didn't order the C.R.I.S adapters that are thirty bucks each!

Live and learn.

Thanks, Doug

[herron]

I had heard the main reason some folks were against using the silver batteries in cameras originally specifying mercury was the rather rapid drop-off in their output.

The old mercury batteries could be counted on for consistency in that regard for a very long time, whereas the silver decline rapidly (and I've heard the zinc-air are even worse).

As often as I rely on a camera meter (almost never), it really doesn't matter to me. "Sunny 16" or my Gossen always seem to work just fine!

I had found a link to a site selling adapters for cameras needing mercury batteries , but I never used one myself (and it is a bit pricey)

[kiev4a]

Ron:

It's the alkaline replacements that have the rapid drop off in output. Sliver seem to hold up pretty well in that regard. You don't ever want to use an alkaline as a mercury replacement.

[herron]

Thanks, Wayne. I learned something here, so now the day can never be a total loss! Is the info on zinc-air correct? I hear their output falls off pretty quickly, also.

I find that I only worry about batteries when they are needed to operate other functions of the camera beyond a meter. On the cameras in my collection that offer a metering system, 9 times out of 10 I don't use it anyhow.

[kiev4a]

Zinc-air apparently are stable. The big problem is they don't last very long. Once you remove the seal to let the air in and activate them. They start wearing out even if you don't turn on the meter. Max life is about six months, depending how hot or cold or humid it is in your area.
That's not a big deal if you are using the hearing aid zinc-air batteries which a pretty cheap. But if you use the one that was specifically made for cameras you are looking at about $10 per battery.

[kamera]

My experience with the zinc-airs...I hate them. I have had camera store personel say to take the battery out of the camera and put the seal tape back in place. No workee for me and I have had them deplete in as short as a month. I quit using them a few years ago.

Have had good luck with the CRIS adaptors but bought mine years ago at about $18 a piece.

Silvers with "O" ring work OK for me in my Spotmatics.

And a lot of times I just say heck with the in-camera meter. Sunny 16, my mind or a hand-held meter are great.

Ron Head
Kalamazoo, MI

[herron]

I guess that's closer to what I meant about zinc airs, rather than undependable output...just output that doesn't last very long! I only used them twice...first time, I thought I must have left the camera's meter on. Second time I knew better.

[mayokevin]

I had good luck with the 1.5 silver batteries that fit the Ftn and I was a slide shooter.