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# Thread: Enlarging to Film - Idea for Metering

1. holmbergers says:

f/1 is a 1:1 light ratio.
You say
Er, no.
but you admit it yourself when you say:

At f1 the film 'sees' an illuminated solid angle of 53 degrees that is the same brightness as the subject
If a camera, with the lens set to F/1, has the same brightness at the film plane as at the subject, then the opposite must also be true. If you set your light meter to f/1, and metered the baseboard image thrown by the enlarger (using a grey card for a reflective meter), then the time given by the meter should be correct. You just measured the brightness of the subject, and at f/1, according to you, the film "sees" the same brightness as the subject. Am I wrong?

2. Originally Posted by Jim Noel
By the time you get all of this calculated so that it is accurate I wil have been able to make at least a dozen enlarged negatives via the good old tried and true test strip method
ditto
Test strip is how it is done.

3. Originally Posted by BetterSense
You admit it when you say .... Am I wrong?
If you feel you are right, be my guest.

4. Originally Posted by Jim Noel
By the time you get all of this calculated so that it is accurate I will have been able to make at least a dozen enlarged negatives via the good old tried and true test strip method ...
Ditto.

Not just the time for calculation -- but the time spent arguing the matter would seem even longer.

5. Ok, like BetterSense says in response to Nicholas, how does that not equal a 1:1 ratio of light intensity? The subject and the the film plane are illuminated to an equal degree... 1:1. Therefore, metering in this way will get you in the ballpark. Metering different areas of the image will give you a range of exposures, and you can make an intelligent exposure based on the film's latitude. Furthermore, it can aid in development/contrast decisions. An enlarging meter would make this all the more easy.

If you feel you are right, be my guest.
What does that even mean?

My thinking is this... when I take a picture of something, I don't make test strips in my camera. I use a light-measuring-device and apply that reading to what I know about my light-sensitive-medium. In this way, I don't have to rely on trial & error, which invariably equals waste.

I'd rather discuss the logistics of how to attain a reliable metering scheme than to be told to make 'just make test strips'.

If you can afford to cut 8x10" panchromatic b&w film into strips, be my guest, but I'm interested in making direct separation negatives from slides, as one example.

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