How do you calibrate a light meter?

[BowerR64]

Do you just cover the light sensor and then 0 it? set it in the dark?

http://i5.photobucket.com/albums/y191/BowerR64/Camera/S3lightmeter.jpg

[Bill Markwick]

Do you just cover the light sensor and then 0 it? set it in the dark?


Hmm, nobody seems to want to tackle this one. I'm not sure why you'd have to recalibrate it (is it acting up after being dropped?), but anyway: buy a gray card at a photo store. It's about the size of looseleaf paper and the gray provides 18% reflectance. You'll gasp at the price for a mere piece of cardboard.

Light it evenly, preferably with diffuse sunlight, and point the meter at it. Recalibrate.

There's an ongoing debate I ain't about to get into, which is that meters should be calibrated at 12% and not 18% and so on. If this is important, Google awaits.

Regards,
Bill

[Warin]

Actually, you cant calibrate it that way unless you have a second meter with a known good calibration. with an evenly lit grey card, how do you know what settings? Depending on the amount of light, it could be evenly lit and still be 1/60 @ f/4 or it could be 1/60 @ f/8. See what I am saying?

You do have to cover the light sensor, ensure it is 100% covered, then set the zero point. And you only need to do that if the meter isnt at 0 when the sensor is covered.

Is that the exact light meter you have? Do you have the luminance attachment? Google the model, find a manual, and check the directions :)

[Bill Markwick]

Actually, you cant calibrate it that way unless you have a second meter with a known good calibration.

Agh! During the transfer from my brain to the net, some bytes fell out! :p

I left out a step - of course you need a second meter or camera to give the correct exposure.

Bill