|A typical manual SLR needs just 1.5 - 3V to run the exposure system|
One of the things about using film vs digital cameras, is that in general, film cameras need far less power than their digital counterparts. Don't forget that that digital wonder is basically a small computer with a viewing screen, operating an auto-focus system. All that takes a considerable amount of stored energy in a battery such that digital cameras usually operate with rechargeable Lithium-ion (Li-on) or Nickel-Metal Hydride (NiMH) batteries. Since film cameras usually need far less power, they typically use small button or penlight cells. In fact, film cameras that lack meters or any electrical operation do not need any battery power at all. A Nikon F only needs a couple of button cells to operate the Photomic head with a meter. It can easily be used without any battery power whatsoever. An Argus C3 doesn't need a battery, nor does a Leica M3. Most SLR cameras that were sold before the late 1970s only need a battery to power the light meter, and lacking that, work just fine without power, although you may need an external light meter or maybe you just want to use Sunny-16 or the Black Cat Exposure Chart. Once the 1980s kicked in, cameras became more sophisticated, and required more power, especially if the camera is an auto-focus model. All those little motors in the lenses, film winding/rewinding, exposure systems, and flashes require more power, which led to larger batteries or battery packs in the camera bodies. In many SLR systems, an external winder may use 4-8 AA cells, which of course adds significant weight. As manufacturers refined the winding systems, by the time auto-focus SLRs became available, the power to run them was contained in a 6V battery, or 2 3V batteries that fit easily into the grip.
|Adding automation requires more computing/battery power.|
Light meters have typically required one or two button cells in a camera. Before the 1980s, cameras that required power for the light meter almost always used Mercury cells. The reason is that Mercury cells gave out a continuous 1.35 V and lasted a long time, and when they went dead, that was it. There was no slow decline in voltage that would give bad meter readings. Then, Mercury compounds were found to leach into the waste systems in landfills, etc., and the Mercury cells were banned. Probably far more cells were used in those light-up sneakers that kids wore than all the cameras ever made. Anyhow, that was the end of them, and older cameras that used those cells were often replaced with newer models by the owners, or the owners scoured the stores for old stock Mercury cells. Old stock cells were still available online until at least 2002.
Cell versus Battery
People often call 1.5 v cells batteries, but technically, they are not. A battery is a group of cells producing a larger output of power than a single cell. Button cells, AA, AAA, C, D cells are not batteries. A 9V transistor battery IS a battery, as are any of the batteries that are more than 1.35 or 1.5V. Your 12 volt car battery contains a bunch of lead-acid powered cells that when joined together, provides 12 volts. Generally, we just lump these power sources under the term battery in common usage, but it's good to know the difference.
Button cells are extremely common in film cameras, especially SLRs, where they typically power the meter and some electronics. They are ubiquitous, and their compact size and 1.5V output usually has them installed in cameras in pairs, so that they provide a 3V output. The most common size is the Alkaline LR-44 cell, followed by the 76S - which is identical in size to the LR-44, but is a Silver-Oxide cell that provides 1.55V with a longer life than the LR-44. A less common button cell in later cameras is the PX-625A. It's now mostly used to replace the PX-625 Mercury cells, but it has a higher voltage than the cell it replaces which may cause meters to be a stop or so off in the readout.
AAA and AA cells
Yes, these are what us old-timers call penlight batteries. They are most typically used to power flashes, and in many older point-and shoots, they provide all the power for the camera functions. Some auto-focus SLRs used them too. The Nikon F100, N90, N8008, and the N2000 all use AA cells as they provide enough power for many rolls of film before they poop out. In addition, the AA and AAA cells are easy to find, unlike some of the esoteric batteries that I will now discuss.
These batteries use more modern technology to deliver lots of power yet, remain compact enough to use in a camera. The late 1980s saw these start to be used in a variety of caameras, but most notably in consumer-level auto-focus SLR cameras. There are a bewildering number of battery types out there, and sometimes you'll find an oddball battery that may cost as much as your $15 Nikon that you found at the thrift shop.
Nickel Metal Hydride - NiMH Batteries
Typically, these are rechargeable cells, such as AA and AAA. They can be used in place of the Alkaline cells of the same size, and the prices are very low. They make a lot of sense for power-hungry flash units, and can usually be recharged a at least a hundred times before they need to be replaced.
Oddball Alkaline batteries
The first one that comes to mind is the 6V 4LR44 battery which is used in the Canon AE-1 and AE-1 Program, as well as the Pentax 6x7. Another is the 6V PX27G. In some cases you can take 4 LR-44 cells and tape them together to replace a 4LR44 battery (which seems to be the reason for that designation). If you have a Yashica rangefinder camera, you'll also be looking for oddball cells, so look at http://yashica-guy.com/document/chrono2.html for more information on your Yashica rangefinder camera.
NiCds were popular in the 1970-80s for rechargeable battery packs, especially in professional cameras such as the Hasselblad EL, the Rolleiflex SLX, and in various flash units. They fell out of favor when Lithium-ion and Ni-MH cells became more common and cheaper in the 1990s. NiCds also have fewer recharge cycles than the newer technologies. However, in some of the cameras that required them, you can still source re-built NiCd packs. Cadmium is a toxic metal, and the old cells need to be disposed of safely. Some cameras that took AA alkaline cells warn against using NiCd cells because they typically only provide 1.2V each.
What about those cameras (and light meters) that used Mercury Cells?
There are a few solutions:
1. Replace the cell(s) with an Alkaline equivalent. The PX-625A is going to be the most common replacement. Of course, it will provide 1.5, not 1.3 volts, and may affect your meter reading. Some cameras use a circuit that the higher voltage still gives an accurate reading. You can compensate with the cameras that are affected by setting your ISO dial to a one stop lower setting. That is, if you are using ISO 400 film, set the dial to ISO 200. To be honest, with C-41 films and most black and white films, there is enough latitude that it won't make a huge difference. You can check it against sunny-16 using a gray card and see what your meter reads. If it's off, you'll know what direction to change it.
2. Replace with a Wein cell - these are basically a modified Zinc-air hearing aid cell with an adaptor to fit the PX-625 chamber.
3. Replace with an appropriate-sized Zinc-air hearing aid cell, and use a spacer to keep the cell in place in the battery chamber. The Duracell 675 hearing aid battery will work in many of the cameras and light meters that require a mercury cell. You may have to shim it in place to not move around.
4. Purchase an MR-9 adapter (http://www.criscam.com/) and use a 76S or LR-44 cell. The MR-9 adapter contains a diode that drops the voltage to 1.3V, and while it may seem a bit pricey, it can be moved from camera to camera as needed. It's the best solution if you want to use a Luna Pro light meter.
5. You can use the camera without powering the light meter, and use an external meter instead. However, some cameras, such as the Nikon FE, require power to fire the shutter at any speed because the aperture-priority mode requires power, whereas the Nikon FM is fully manual, and the shutter can work without power. The Pentax K1000 and the Pentax Spotmatics are also fine without using a battery for the meter, as are most M42-mount SLRs. Many of the older Canon SLRs such as the FTb work fine battery-less. You just have to use an external meter.
NOT ALL CAMERAS NEEDED BATTERIES FOR METER POWER
There are numerous cameras that used solar cells to power the exposure system. The Olympus Trip 35, Konica EYE, and the Canon DEMI are good examples. Most of the examples date from the 1960s and 70s. A ring of cells around the front of the lens is a sure bet that the camera is powered by a Selenium meter.
It makes good sense to store your camera without the cells or battery in it if you are not going to use it for awhile. This holds especially true for cameras that use AA aand AAA cells - which will leak over time and ruin the camera. I can't stress this enough. I have seen far too many contacts ruined to the point of no-return by leaking AA cells. Whether it's a camera or a flash unit, remove the cells before you put it away for any length of time. Button cells seem much less likely to cause problems in storage, nor do Lithium batteries. The real culprits are the AA and AAA cells which can do the damage when they leak over time.
You can store fresh batteries in in the fridge if you wish to prolong their storage life, but I have never tried it to see if it makes a difference. Certainly high-heat will degrade them, since chemical reactions are accelerated by higher temperatures.
With the advent of digital photography, the market for camera batteries shifted to rechargeables, and the prices for non-rechargeable camera batteries have gone up. If you look for a CR123A battery at your local store, be prepared for sticker shock. I buy most of my button cells and Lithium batteries online, either via Amazon or eBay. A pack of 100 LR-44 cells can be had for less than $15 online. There are plenty of online sources for batteries, but I still buy my AA and AAA cells locally.
BATTERY CROSS-REFERENCE CHART - Not all manufacturers use the same numeric designation for a particular size, but this chart will be helpful.
CAMERAS AND POWER SOURCES (obviously NOT a complete list, but it's a starting point)
PX-625 Mercury cells:
NIKON - F Photomic prism, Nikkormat FT, FTN;
CANON- QL-17, EXEE, F-1, FT QL, FTb, FX, Canonet 28, TL, TLb, TX
OLYMPUS - OM-1
LEICA - CL
MINOLTA - SR-T series, Hi-Matic 7, 7S, 7SII, 9;
PETRI - Color 35,
KONICA - Auto S, Auto S2, Auto S3, Autoreflex T, Autoreflex TC, C35, FP,
KOWA SE, SET; ROLLEI 35, YASHICA TL-Electro-X,
PX-400 Mercury cells
A great number of Pentax Spotmatics used this size Mercury cell. However, you can use a silver-oxide cell without fear of affecting the exposure accuracy. The Spotmatics use a bridge circuit so that whether the source is 1.35V or 1.5V, you'll get the same result. I recommend using a 392 (LR-41) silver-oxide cell for the Spotmatic SP series, and a PX625A for the Spotmatic F.
PX-27 Mercury batteries (5.6V)
MINOX LX, Minox 35 series;
ROLLEI 35 TE, ROLLEI 35 SE, ROLLEI 35 LED
LR-44 or S-76 cells (1.5V)
(Typically there are 2 in series, for 3V total. You can often use a 1/3N battery, which replaces 2 LR-44 cells. They tend to be more expensive than the 2 LR-44s , though.)
NIKON - Nikkormat FT2, FT3; Nikon FM, FE, F2, F3, FM2, FM2N, FE2, FA, EM, FG, FG-20, FM3A, FM-10
CANON - T60
OLYMPUS - XA series, OM-2, OM-10, OM-4, OM-PC
PENTAX - K1000, ME, MG, LX, Super Program, P30T,
MINOLTA - X370, X570, X700; CLE, XD series, XG series,
YASHICA - CONTAX - Contax 139, Yashica FX D, FX-3, FX-7,
KONICA - FP-1
CANON- AF35ML, Sure Shot AF10, T-50, T-70, T-90
NIKON - N4004, N8008, N90, F100, F4, F5, L135AF,
KONICA- FS-1, MG, TC-X
MINOLTA MAXXUM 5000, 7000
4LR44 (6V)(= PX28, A544, 476A)
CANON AE-1, AE-1P, A-1, New F-1, AT-1, AV-1
NIKON Nikkormat EL, EL2
YASHICA Electro 35CC, Yashica FR, Yashica FX-1,
CR-2 Batteries (3V) (Most SLRs use 2)
NIKON- APS Pronea 6i, N55, N65, N75
PENTAX - MZ-S, Z-5, MZ-10, ZX-10,
CANON- Rebel 2000, Rebel K2, EOS IX, Sure Shot 130u, Sure Shot Classic 120
MINOLTA - QTSi, XTSi, Maxxum 5, HTSi
CONTAX G1, G2, T3,
CR-123A (3V) (Most SLRs use 2)
NIKON - N60, N80, N70, One-Touch 90 Zoom,
CANON - EOS Rebel G, ELAN 7, EOS 30v, Sure-Shot 105 zoom, Sure Shot 60 zoom, Sure Shot 70 zoom, Sure Shot 80 zoom, Sure Shot A-1, WP-1, Sure Shot M, Sure Shot Max
MINOLTA - Maxxum 7, Maxxum 9
CR-223 or DL223A (6V)
may replace 2 CR-123 in some cameras
CANON- EOS 650, EOS 620, 750, 850, 100, EOS 3, A2E, Sure Shot Zoom XL, EOS-1V
NIKON - N50, N6006
MINOLTA - 7000i, 9xi
PENTAX- SFX, SF-1; SF-7, SF-10;
KONICA Hexar, Yashica T2
Okay, you have read this far! If you have a fully manual, non-meter camera such as this one, no battery needed! You are ready for that desert island trip.