Silver oxide batteries are available in two types. For Energizer batteries the better style is the 'H' series, examine
the discharge curves:
Likewise the 'SR44' and 'SR44W' are preffered over the 'SR44SW'.
The distinction seems to be the electrolyte, KOH providing a flatter discharge than NaOH.
That's like 2 different batteries!! I will go for the 357H when it's time! What's this SR44 and SR44W refer to? I guess batteries as that looks familar from a different camera I had? I do thank you for the info and help you given me on this conversion I'm about to try? It is a simple procedure yes? Do you think I should have the camera's meter checked after having this done to see how correct it is?
Have a good one,
Forgive me if this is a dumb question, but why not just use 1.5v batteries and re-adjust the film speed accordingly? ISO 100 at 1.35v becomes a meter setting of ISO 25 at 1.5v.
Does higher voltage damage the meter?
I shoot this way with a Miranda Sensorex and it works fine in EE-auto and manual mode.
I don't think there are dumb questions in life just dumb answers!! That said I must ask where the formula came from to make the adjustment of the camera setting for film speed? And I would have to wait for others to answer on the possible damage caused by higher voltage? Though I have to wonder as It's not a lot of difference but then I am brain damaged and have been very wrong in the past on things!! I will at least see how much it cost to have a pro add the diode to the battery circuit and hope I can afford it before the mercury battery goes dead! Or as my Friend in NZ would say suck a Kumara!! Any other replies?
The difference in battery voltages will cause no damage to any electronics. Camera meters operate at minuscule power levels, even if the voltage is raised by by the use of the wrong battery the extra 3 millionth of a watt isn't going to do anything. Voltages have to rise quite a bit higher to damage any integrated circuits and such, and most old cameras use only resistors and a meter.
How the camera responds to a change in battery voltage depends on the design of its meter. Older stop-down meters that center the needle should be relatively oblivious to any change in battery voltage. How well open aperture meters will work with an adjustment to the ASA depends on the design of the meter: simple meters may work over a wide range of light intensities; very sensitive meters with linearizing and amplifying circuits may need different ASA adjustments for low light and bright light.
Adjusting the ASA to compensate for battery voltage is a workable solution that works better with some cameras than others.
All of which is no news.
I recalibrate the ISO setting as follows.
Originally Posted by Terry Again
Bright sunny day, ISO 100 film, we all know the setting will be f16 at 1/125th.
I insert a 1.5v battery in place of the required 1.35v battery.
Adjust your meter setting to see which ISO setting tells you to shoot at f16 @ 1/125th.
In most cases I have found a setting of ISO 25 at 1.5v equals a setting of ISO 100 using 1.35v.
For what it's worth
I have SRTs and some other cameras the were built for mercury cells. The Wein cell is a zinc air cell.
What works for me though is Walgreen's 675 Premium Zinc Air hearing aid batteries. They put out 1.4 volts. They have a smaller diameter than the Weins. Take your camera to the car parts or hardware store and get an O-ring to fit inside the battery compartment and surround the 675 cell. This set-up works great for me.
IN-6263 schotkey diodes. Drops the 1.55v of silver oxide batteries to approx.1.35v. I've used them for years in the Olympus OM-1/1N. When you test the meter with your calibrated light test box, you'll see that the meter is linear though it may need a little tweeking through the regular adjustment method. Absolute accuracy may not be that critical if you are shooting color negative film (which has a wide exposure tolerance). If you need a couple of these diodes, $1 each + $8 S&H. Pay by paypal if you like., John, www.zuiko.com
One of the best things about the SRT's is they don't need no stinkin' batteries... ;)
Wrap a 1.4V alkaline 675 hearing aid battery in a correctly sized split washer to take up the empty space and there you have it; the best practical 625 replacement option. They are perfectly accurate and they are *dirt* cheap too. I buy them anywhere in multi packs of five for $3. I find them much more accurate, consistent, long lasting, and economical than Wein cells, which I used for years before a repairman tipped me off to the 675 method. Going this route not only gives better results, IMO, but also lowers the yearly cost per camera to about $1.20 (changing every six months), where it was about $24 per year per camera using Wein cells (changing every three months). With four Canon FD bodies, a Nikon F Photomic T, and a Canon FTb low light booster, I was going through Wein cells like mad, and results were all over the place. None of my cameras ever matched my spot meter or each other with Wein cells. Not so with the 675s.