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Doug Clifford from Ace Camera Index

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Can't Find The Battery Your Camera Needs?
Overcoming the Mercury Battery Ban

Millions of perfectly functioning older cameras and light meters have been affected by the mercury battery ban in the United States. More than 100 cameras and meters made by famous names such as Nikon, Canon, Pentax, Minolta, Gossen and Sekonic depended on the 1.35 volt PX-13 / PX-625 mercury battery.
Camera manufacturers didn't protest this ban nor have they offered any solutions for the owners. Instead they see this as a windfall opportunity to sell millions of new cameras.

Major battery manufacturers haven't been much help either. The alkaline batteries offered as replacements for the PX-13 / PX-625 are poor substitutes for the reliably consistent voltage supplied by mercury photo batteries.

For example, Duracell's new 1.5 volt PX-625 alkaline battery yields inaccurate light meter readings and underexposed pictures. In the first place, it's the wrong voltage. If the 1.5 volts were consistent it would be relatively easy to manually compensate for this, but alkaline batteries (unlike mercury cells) decline in voltage during their lifespan making it near impossible to accurately adjust the meter reading. Varta also makes an alkaline substitute.

Cameras and meters using the alkaline substitute have been reported to be inaccurate by as much as 1.5 stops. This is a total disaster for photographers who shoot slide film. Even a one-half stop exposure mistake with transparency film can mean the difference between a perfect slide and garbage, especially in contrasty lighting situations.

If you shoot only color print and b/w film, are willing to manually overexpose every image (you'll have to determine by how much through trial-and-error) and you're willing to discard and replace the alkaline battery well before it expires (another guessing game) then the Duracell substitute is a marginal solution.

Once you understand the pitfalls and limitations associated with using the alkaline substitute battery, you'll want to examine other more desirable solutions to keep your old camera in perfect working order.

Some Solutions Are Better Than Others

A range of solutions have come to the rescue of all this wonderful old photo equipment. Some are better than others.

Varta PX625 mercury battery
Varta still makes them

Family and friends abroad. Mercury batteries are still manufactured in Asia and Europe and will continue to be available there for the foreseeable future. Varta in Germany continues to manufacture mercury photo cells, according to a recent visit to their web site. Some recent postings in newsgroups indicate there are Canadian mail order sources for mercury batteries.

If you travel abroad you can stock up on mercury batteries and bring them back when you return. At least three years worth of batteries can be stored in the refrigerator; refrigeration prolongs their life until needed.

At this time it is not illegal to import mercury batteries for personal use into the United States. (It is illegal to sell them in the US.) Congress will undoubtedly close this loophole if it becomes apparent that large numbers of mercury batteries continue to end up in landfills. Protect the environment by saving all batteries for hazardous waste disposal available in many urban areas, otherwise don't be too shocked to read about someone being arrested at some airport because they had a suitcase full of batteries.

Visiting your camera repair technician. You can have the light meter permanently recalibrated to compensate for the higher voltage. This is a pricey solution, costing $70 or more depending on the camera model and only makes economical sense if your camera is being serviced for other problems. Additionally, the camera technician will adjust the meter to work at medium light levels, meaning the meter may be inaccurate at high and low light levels. This doesn't solve the problem of the declining voltage found in alkaline battery substitutes.

Unfortunately a few camera models, including my two Canon F-1's can't be recalibrated.

Wein zinc air cells. These batteries have been developed by Stan Weinberg and Bob Shell (editor of Shutterbug Magazine) specifically to provide an accurate replacement power source for older cameras. They are distributed by Saunders and can be found at many local camera stores. Retail price in Seattle is about $5. Previously zinc air cells were most commonly used in hearing aids.

Although Wein cells come closest to matching the voltage output of mercury batteries they have several shortcomings. First, they require air for the cell to produce electricity. This means if your battery cover doesn't have a small hole for ventilation, you'll have to add one. (Hint, think Dremel, not Black & Decker.)

Wein cells come covered with a stick-on tab. Once the tab is removed and air is allowed to reach the battery electrolyte, its life begins. Don't throw the stick-on tab away because you will need it! Wein cells have a short life, about two months, whether the cell is in use or not, however you can substantially prolong the life by removing the cell after every use and recover the air hole with the sticky tab which puts the cell back to sleep. Otherwise plan to buy about six batteries a year.

This gets expensive if you can't remember to do this. It also effectively prevents spontaneous picture-taking if you have to install the battery every time you want to take a picture. There are reports the Wein cell requires 30 minutes to come up to working voltage.

What causes Wein cells to die is the electrolyte dries out. People in dry climates find Wein cells have very short lives so I pose the obvious question, can we add water through that tiny hole?

The MR-9 Battery Adapter. Anecdotal reports in newsgroups and on the web suggest the MR-9 Battery Adapter is the best answer for photographers seeking a trouble-free solution.

Graphic of silver oxide 76 battery being inserted into the MR-9 Battery Adapter

silver oxide 76 cell (easily obtained)
fits inside the MR-9 Battery Adapter

The MR-9 Adapter is a sleeve which accepts the readily available 1.55 volt silver oxide 76 cell. The outside dimensions of the MR-9 approximately match the size of original PX13/625 mercury cells. (Because it's slightly thicker, the battery cover may not screw in as deeply as before.) Silver oxide cells share two characteristics with the banned mercury batteries: they yield consistent voltage throughout their lifespan and decline quickly when their life ends.

The adapter contains micro-circuitry which steps the voltage of the silver oxide 76 cell down to a consistent 1.35 volts.

The advantages offered by the MR-9 explain its popularity. The battery adapter is a one-time purchase and is reusable over and over again, your camera meter doesn't have to be recalibrated, no exposure compensation is necessary, and the silver 76 battery should last a year or more. In short, it's back to picture-taking as before.

The MR-9 Battery Adapter costs $29.95 (plus s&h) and can be purchased directly from the US Importer, C.R.I.S. Camera in Chandler, Arizona. C.R.I.S. has an FAQ about the adapter on its web site and also lists more than 100 cameras and meters which can use the MR-9.

Now if someone would just come up with a solution to replace the 5.6 volt PX32 mercury battery required to operate my beautiful $300 Sekonic flash meter I'd be totally happy.

Share your thoughts!

Doug Clifford

(Doug Clifford is the webmaster for the ACE Indexes, an annotated directory of North American photo commerce web sites, expanding soon to include Australia, New Zealand, the United Kingdom, Europe and Asia.)

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