Through the lens metering

[john.l.barford]

Tapatalk appears to only accept one photo at a time

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[john.l.barford]

Tapatalk appears to only accept one photo at a time

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I am seriously unimpressed with tapatalk

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[Dan Fromm]

Since you responded, what is your "relevant" technique? Something that falls outside of empiric physics like most of your posts?

Why do the calculations when meter, shoot, develop, measure film density will do?

I'm all for models and using them but direct measurement is, well, more direct.

[Drew Bedo]

Yes . . .please publish the Meter info.

I fooled around with this years ago trying to use photo cells from Radio Shack and a multimeter. Mounted ity all to a film holder (lots of Epoxy putty) and tried it out. Lack of linearity and other things lead me to realize that I didn't have the electrical engineering backround to get this done . . .and dropped the project.

[john.l.barford]

Through the lens metering .
To make this meter you will need.
1) A LUX METER. Plenty of these on e bay. You will need one where the sensor head is seperate from the meter joined to it by curled wire.
2) a solar cell roughly 4x5 inches (plenty of these on e bay)
3) an old 4x5 film holder
4) bits of wire

Glue the solar cell into the film holder.
Cut sensor off lux meter
Wire lux meter to solar cell
Put film holder in camera
Test
Match readings on lux meter to light meter readings
And type up conversion table.

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[Dan Fromm]

Cute. How well does it work in dim light?

[john.l.barford]

It is able tto cover all exposure values (EVs) from 1 to 16

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[stevelmx5]

Out of interest, how would having the lux meter behind the lens account for shutter speed? I understand you could set the desired aperture then open the shutter on bulb to get a lux reading but what conversion would you apply to get ISO/shutter?

[Jody_S]

Through the lens metering .
To make this meter you will need.
1) A LUX METER. Plenty of these on e bay. You will need one where the sensor head is seperate from the meter joined to it by curled wire.
2) a solar cell roughly 4x5 inches (plenty of these on e bay)
3) an old 4x5 film holder
4) bits of wire

Glue the solar cell into the film holder.
Cut sensor off lux meter
Wire lux meter to solar cell
Put film holder in camera
Test
Match readings on lux meter to light meter readings
And type up conversion table.

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FYI, any voltmeter will do if it's accurate in the 0-1.5V range. But an accurate volt meter might cost more than a cheap lux meter from China. Also, you could mount a smaller photovoltaic cell on a thin piece of spring steel, then you would have a through-the-lens 'spot' meter that will read specific areas of interest, that you can position by sliding it about in the holder.

[john.l.barford]

To calibrate the through the lens meter
I suggest that at first you use the lux meter
(before you chop off the end) and print out a LUX to EV conversion table from the net. Use the lux meter as an exposure meter and familiarise yourself with converting its readings to exposure values you are happy with.
Make the through the lens meter. the readings from this will not be the same as the lux meter they may be bigger or smaller this does not matter. For example the lux meter will read between 320 and 640 for an exposure value (EV) between 7 and 8 . If the through the lens meter reads, say, between 1280 and 2560 (too high) simply move all the lux readings on your table down a place.
Hope this helps

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