How do I determine F number for PS 200 flash with Olympus Trip?

03-23-2009, 04:34 PM

On the back of my PS 200 flash is a chart which applies to ASA 100 films, however I am most likely to be using faster films, such as ASA 200, 250, 320, 400 How do I work out the correct F number setting for my camera?

Thanks

**T?R** · 03-23-2009, 04:35 PM

ASA 200 emulsion is twice as sensitive as 100, 400 is four times etc.

It really is as simple as doing division in your head.

So 1/60 exposure for a 100ASA film will need only 1/120 for a 200ASA

Or in f numbers, one 'stop' for each doubling.

f8 for 100ASA, f11 for 200ASA, f16 for 400ASA

**T?R** · 03-23-2009, 04:35 PM

ASA 200 emulsion is twice as sensitive as 100, 400 is four times etc.

It really is as simple as doing division in your head.

So 1/60 exposure for a 100ASA film will need only 1/120 for a 200ASA

Or in f numbers, one 'stop' for each doubling.

f8 for 100ASA, f11 for 200ASA, f16 for 400ASA