Meter modification (dumb question)

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De_Corday

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so... dumb question. All these how-to's about making adaptors for cameras that are supposed to take 1.35v...
I have an old nikkormat I'm restoring as a kick-around body. PX625's are still available in alkaline. Can't I just wire a diode in series with the battery socket? or am I missing something basic? (EDIT: I initially posted about wiring a resistor in series. Which I'm pretty confident wouldn't work, what with ohms law and all)
 
Placing a 1N5711 schottky diode will drop voltage to 1.35v if using a 357 silver oxide battery with spacer. See my page here http://www.colynsfotografs.com/srt.html This is for a Minolta srT camera but you can scroll down to see what I am talking about..

Adjusting the meter is only needed if it has been adjusted out of spec by someone else.
 
An important consideration here is that a silver oxide battery holds a steady voltage like the mercury oxide battery did. An alkaline battery does not hold a steady voltage and does not provide accurate or consistent metering performance.

- Murray
 
I have an alkaline 625 in there now, and compared to my trusty F2s it seems to be overexposing a stop and change. Close enough for rock-and-roll/negative film, I suppose? 😀
 
I've always shot slides, so a consistently accurate meter has always been important to me, be it in-camera or handheld. I can't imagine exposing any film inaccurately, but this may depend on what you're photographing. I do landscape and nature, and exposing carefully for the desired effect and interpretation of the scene is critical. Street photography with B&W film may be more forgiving in this regard.

The alkaline battery doesn't provide consistent voltage. It starts at 1.5v and then tapers off gradually until it runs out. A silver oxide or mercury oxide battery will hold a steady voltage, then drop of suddenly at the end. Some newer cameras have an internal calibrating device that compensates for an alkaline battery's inconsistent output. The older cameras that took mercury oxide batteries have no such circuit, so they read inaccurately.

If the battery is causing the meter to provide readings that are over a stop off, and you can't even trust the meter to be off by the same amount as the battery runs down, I would find such metering to be useless.

- Murray
 
BAT41 and 3/32" heat shrink works well for me. Get diodes that are static proof.

I think the main question is whether you have experience soldering, it's a careful, precise kind of thing and you need to have a properly tinned iron and know how hot it is, by experience. You don't want to be noodling around. If you haven't done much soldering, I don't think a camera is a good place to start, you can practice on some some similar components and wires .I don't think it's THAT critical to modify the camera if you are using a silver oxide battery and adjusting the asa for minimal deviation.
 
George Bonanno said:
Come on... are you shooting for Vogue or High Times ? Get a grip on life... go out of your comfort zone and take pictures. Try Ludlow Street or Garden Place afterhours... guaranteed excellent street shots.
Click to expand...

So....are we supposed to do things your way?? If we're not supposed to do it right, why have a meter builtin??

I prefer correct meter readings. That is why I use the diode fix.
 
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