What is a good, cheap handheld exposure meter ?

336v said:

I should mention that this is not quite accurate statement - the forward voltage drop on any diode, Schottky or plain, is not fixed - it can be 0.21V only for certain current flowing through it (let alone only at certain temperature), e.g. this voltage is highly current dependent. In case of usage in Luna Pro - meaning this drop will be different depending on which scale you're taking the reading at: the meter draws ~10...300uA on low scale, ~50...500uA on high scale and ~200uA during "Batt Check". So the diode voltage drop will vary depending on what you're doing; the diode will not only introduce non-linearity, but inconsistent one. Small, but noticeable. For most users it's just small enough not to matter, but it's there. The right way to deal with this is to make a proper voltage regulator with fixed 2.7V output.

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I don't want meter with 1/2 stop EV error.

Yes, I hear you, that's why I used real 2.7V LDO regulators, not forward biased diode. As of EV error, I must say two well calibrated meters may easily differ by this amount - highly dependent on how you point the meter to the subject, spectra of light (if sight sensors are made with different technologies - it's impossible to compensate exactly, to make one meter function as the other) , and few other variables. In short - if you have more than one meter, you likely have up to 1/2EV readout difference between them already, whether you want it or not.

I use plain-ole batteries in legacy equipment that would otherwise use mercury cells. When the batteries are new, I find a 2x change in the meter's ASA dial brings the meter into line. This changes a bit at low light, but then I switch to a handheld meter and/or change the adjusted ASA so the old meter reads correctly for the new lighting conditions. I change the batteries out for fresh ones when the 2x correction no longer holds.

There is no point sweating a 1/2 stop 'error' in metering film. The vagaries of subject matter and lighting contrast means there is rarely a correct exposure - all exposures will be a compromise. With modern film, as long as the exposure is generous enough then everything will be copacetic. The final exposure is determined when the negative is printed and adjustments made with dodging and burning. If the negative is the score and the print the performance it is only necessary that the negative capture all the notes in the 'score.'

Chan Tran said:

I don't want meter with 1/2 stop EV error.

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To truly evaluate exposure effectiveness I’d plot curves and check resulting subject negative densities.

Very often I find my densities so far up the straight line that I question what I was thinking when I planned the exposure. That’s in usual day-to-day picture taking.

I’ll try to come up with another example again sometime. I have done the testing carefully in the past. Last time it was a picture of my dog and a gray card and the result was 1/6 stop away from what I expected.

Bill Burk said:

To truly evaluate exposure effectiveness I’d plot curves and check resulting subject negative densities.

Very often I find my densities so far up the straight line that I question what I was thinking when I planned the exposure. That’s in usual day-to-day picture taking.

I’ll try to come up with another example again sometime. I have done the testing carefully in the past. Last time it was a picture of my dog and a gray card and the result was 1/6 stop away from what I expected.

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Well so you say since you can't get your film to behave you don't need good meter? I would shoot film without a meter any day but I don't use a meter that is not accurate. I have a good number of camera that takes mercury battery for the meter I simply just use them without meter. Besides an exposure meter I don't know any kind of measuring instrument that a 25% off is good enough accuracy.

I’m kind of the same way. I want my exposure meters to indicate 32 candles per square foot when they are looking at a 100 foot lambert reference light source.

Not 25

Regarding the use of zinc air batteries to replace the old mercury type batteries, here is an article from a 1995 issue of Popular Photography. They found less than a one third of a stop difference whether Mercury batteries, Wein Cell batteries or off the shelf Zinc Air batteries were used in a Gossen Luna Pro.