EXPOSURE CALULATION

[Doyle Thomas]

Assume an aperture of f/166 and an ISO 100 then

f/128 at 64 is the same (2/3 stop)
f/90 at 120 is the same
f/64 at 250 is the same
f/32 at 500 is the same

So if I set the meter at ISO 500 take a reading and set the stop at 32
it should tell me exposure time - reciprocity at f/166?

 

[tpersin]

i believe the simplest way is to set your meter for f16 and iso 100, multiply the resulting exposure value by 100, and then adjust for reciprocity...

good luck!

-tom

 

[Doyle Thomas]

Assume an aperture of f/166 and an ISO 100 then

f/128 at 64 is the same (2/3 stop)
f/90 at 120 is the same
f/64 at 250 is the same
f/32 at 500 is the same

So if I set the meter at ISO 500 take a reading and set the stop at 32
it should tell me exposure time - reciprocity at f/166?

ok, now I have my Mind right. its:

Assume an aperture of f/166 and an ISO 100 then

f/128 at 64 is the same (2/3 stop)
f/90 at 32 is the same
f/64 at 16 is the same
f/32 at 8 is the same

So if I set the meter at ISO 8 take a reading and set the stop at 32
it should tell me exposure time - reciprocity at f/166.

 

[Jim Noel]

If the camera uses 35mm, 120 or 5x4 film, use Fuji Acros and forget about reciprocity calculations. That is the only film I use in pinholes of these sizes.

 

[Helen B]

You missed out f/45:

f/128 at 64 is the same (2/3 stop)
f/90 at 32 is the same
f/64 at 16 is the same
f/45 at 8 is the same


Best,
Helen

 

[Doyle Thomas]

Thanks!

Assume an aperture of f/166 and an ISO 100 then

f/128 at 64 is the same (2/3 stop)
f/90 at 32 is the same
f/64 at 16 is the same
f/45 at 8 is the same
f/32 at 4 is the same

So if I set the meter at ISO 4 take a reading and set the stop at 32
it should tell me exposure time - reciprocity at f/166.

 

[tpersin]

or, another way, would be to set your meter for f16 and iso 100, multiply the resulting exposure value by 100, and then adjust for reciprocity...