Have slowly begun to get to grips with my new Pinsta.
I do have a question that I hope someone here could help with.
I've been calculating the exposure by taking an incident meter reading on a hand held light meter.
Taking a note of the reading at f 16 and then calculating the overall exposure time from that with an available formula.
My question is, as the Pinsta is f 229 would reading the light meter 2 stops lighter and calculating the exposure from that rather than f 16 make any differance other than shortening the overall exposure time?
What is the signifcance of taking the light meter reading at f 16 rather than any other f stop?
Thanks
To convert f/16 to f/229, is a simple calculation.
Divide the camera f/number by the light meter f/number, and then Square the answer to give a Multiplication Factor.
e.g. ( f/229 divided by f/16 ) = 14.3, and then 14.3 ^2 = 204 MF
Multiply any exposure times indicated on the Light Meter at f/16 by 204.
Example 4 sec at f/16 would be 816 sec at f/229
You might find that various tables give answers that differ by a few seconds, for long exposures that won't make any noticeable difference.
The relative change of 2 stops at f/16, is the same relative change as 2 stops at f/229.
There is no significance of taking a reading at f/16 than any other f/number. Just use what ever is convenient for you/your meter is capable of, and convert it. However for long exposures be aware, depending upon what photographic medium you are using, especially film, that the calculated exposure may not follow as expected due to Reciprocity Law Failure. In this case refer to the manufacturers data sheet and convert the exposure time to compensate for RLF. You don't need to do that HDPP.