Pentax Spot Meter - quick check?

[Calamity Jane]

My old Pentax Spot meter started acting up while I was on my trip in July - the "high range" readings became erratic. When I got home, I cleaned the Hi/Lo range switch contacts and it seemed fine. The next time I went to use it, the high range was dead. I took it apart again and found numerous poor solder joints (which I repaired). I did some 4x5 copy shots for POP prints, overdeveloped 25% (as usual for POP) and they still came out thin (. . . scratches head . . .) ? ? ?

I don't have another meter (that I trust) and I don't even have a grey card.

Is there any way to check a spot meter without another meter or grey card (other than exposing a test print)?

Thanks . . .

[Guy Boily]

Well I guess your next purchase will be a grey card. Here is what I do when my grey card is not available. On a bright sunny day, go out, put the palm of your hand (clean if possible) in direct sunlight and take a reading. It should read 16 on the EV scale or f16 1/250 with ISO 100 film. This should tell you if the meter is working properly.
Cheers.
www.guyboily.com

[David Roossien]

Can you borrow someone's 35mm camera for a few minutes to check your readings? Obviously this won't be a perfect solution, but it should get you close to an accurate reading--certainly better than 25% off. I have a couple of 35mm cameras with spot meters in them that are consistent with my handheld spot.

[Michael Kadillak]

Immediately get a backup meter, even an inexpensive incident and Fed Ex your spot meter to Richard Ritter for a complete overhaul (including a list of your repairs) and a calibration. He does good work and with meters he is quick.

Everyone should have a backup meter or at the very least a plan B for handing these unscheduled events. And they happen at the most inconvenient times.

Cheers!

[Leonard Evens]

On a clear day without haze or smog, point your meter up high in the blue sky away from the sun. It should read very close to 14. This invariably works for me in suburban Chicago.

That will give you an absolute reference point. Next you should check if the scale reads properly for other light levels. You can use the inverse square law for this. Use an open light bulb and place a white sheet of paper some distance away from it. The bulb should be as close to a point source as you can make it, and it should be far away from any reflecting surface such as a white wall. Take a reading. Now move the paper 1.414 times as far away and take a reading. It should read one stop lower. Then move twice as far away and take another reading, it should be two stops lower. Etc.

This should give you at least a rough idea if the meter is okay, but there are lots of things that can go wrong. Snce your meter is one of the most important parts of your gear, it would be better to have it recalibrated by an expert. Also, the suggestion to get an inexpensive back-up non-spot meter makes sense.

[Calamity Jane]

Guy: "16 on the EV scale or f16 1/250 with ISO 100 film"

The meter is right on the money!

Thanks Guy, I am going to write that one in my notebooks for future reference :-)

[Michael Kadillak]

You indicated in your original post that after finding the high range of your meter non-responsive you opened it up and repaired some poor solder joints and after using it for some copy work it gave you some questionable results (thin negatives) .

I realize that my engineering training may cause me to be a bit more stringent in my approach to this subject, but how can you possibly say that you are comfortable (The Meter Is Dead On!) with a single data point correlation to a "rule of thumb" recommendation. I guess that if all you are going to measure is sky, then maybe all is well, or maybe well enough. What about the correlation to the rest of the spectral response? Your meter is designed to be able to provide you with 1/3 stop increments. Is possibly +/- 2 stops within the low range acceptable? Meters are highly sensitive electronic devices that need servicing at regular intervals.

If the gas mileage of your car declines but the engine "sounds OK to me" would you not get it looked at? Try to figure out why you are having an anomolous experience - particularly at these fuel prices.

Film paper and chemistry are not cheap these days. Considering the investment we all make in these materials, I feel that the inherent protection of the investment in these materials is having your peripheral devices (meters and shutters) properly calibrated. Anything less is at the very minimum problematic. We each need to detemine if the risk we accept (or mitigate) in proportional to the probable outcome. Considering the inconsequential cost of a proper calibration, this is truly a no brainer.

Whatever works for you!

[Hans Berkhout]

One should check a lightmeter periodically: For sensitivity with a Wallace Expo Disc. For linearity with a 10 stop ND filter.

[Alec Jones]

I'd get it fixed. It's too important to mess with and the cost will be less than lost shots and mad customers. A good repairperson for these is Richard Ritter. http://www.lg4mat.net/

[robert_4927]

Do you think someone should tell her about the battery supply on an old Pentax spot meter in the high range? Nah, it's dead on metering her hand so it must be ok....lol... I just love some of these posts....lol... makes my sides hurt at times.