Indoor Pinhole Exposure times.

M

myequation

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I'll soon be testing out a new 6x12 pinhole camera.

.3 pinhole f/135

I understand outside exposure times with the help of the chart on the back of the camera.

But what about indoors.
The exposure calcilators are confusing.

Lets say my light meter reads 1/10th @ 5.6 with 400asa
How would I figure out the pinhole exposure?

:bang:

And also would using a flash help with pinhole?
Lets say I fire the flash several times and bounce the light off the ceiling?





 
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Reciprocity failure isn't directly due to the f/stop. It's only affected by the exposure time, and it varies from one film to another. Thanks for that link, Micky D!
 
f/135 (well actually f/128 is, but who cares with details like these?) is 9 stops removed from f/5.6 where you measured. Taking that you use film (?; reciprocity? ) or for good measure, expose 2^10 (10 stops longer than the f/5.6 measurement suggests: 2^10 = 1024, say 1000 times as long as measured: so indoors the measured exposure of 1/10 sec will have to be stretched to 1000 * 1/10 = 100 sec at f/135, or two minutes among friends.

I find this 1000 times fascinating: no table to consult, can be multiplied in one's head in the field etc. Just measure exposure for a ten stop wider aperture than your pinhole camera and multiply the measured exposure time for the given ISO by 1000. Add a stop or two, i.e., double or quadruple the exposure time for reciprocity and you are set.

Say, you were using that 400 ISO film outdoors, 1/500 sec, f/11 standard exposure, i.e., 1/2000 sec at f/5.6 equivalent for an aperture 10 stops wider than the pinhole's f/135.
Now multiply the time by 1000 or expose for 1/2 sec at f/135. This will come out very well, I am certain. 1/2 sec needs no reciprocity add on.
 
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