RicardoD
Well-known
This may be a dumb question, but I learned a long time ago to swallow my pride and ask anyway, so here goes...
On the ISO film speed dial on my new-to-me Bessa R there are the obvious film speed settings called out by the white squares and number (e.g. 100,400,1000, etc).
But in between these labelled settings are small white dots, or tick marks. The progression is as follows:
25 * * 50 * * 100 * * 200 * * 400 * * * 1000 * 1600 * * 3200
So the question is between the labeled film speeds say, 400 to 1000, is the progression linear? In my example, 1000-400 = 600 divide that by 4 and you get 150. So the linear progression would be 400, 550, 700, 850, 1000. But often on other cameras with everything labelled and equally spaced , you will see something like 400, 500, 650, 800, 1000 which is a non-linear progression.
Can anybody tell I a mechanical engineer and like things precise? Or perhaps does it even matter considering that I am obsessing over fractions of a stop?
I just want to make sure I know where 800 and 1250 are which seems pretty obviously one tick before 1000 (for 800) and the tick between 1000 & 1600 for 1250 (Tri-X in Diafine).
On the ISO film speed dial on my new-to-me Bessa R there are the obvious film speed settings called out by the white squares and number (e.g. 100,400,1000, etc).
But in between these labelled settings are small white dots, or tick marks. The progression is as follows:
25 * * 50 * * 100 * * 200 * * 400 * * * 1000 * 1600 * * 3200
So the question is between the labeled film speeds say, 400 to 1000, is the progression linear? In my example, 1000-400 = 600 divide that by 4 and you get 150. So the linear progression would be 400, 550, 700, 850, 1000. But often on other cameras with everything labelled and equally spaced , you will see something like 400, 500, 650, 800, 1000 which is a non-linear progression.
Can anybody tell I a mechanical engineer and like things precise? Or perhaps does it even matter considering that I am obsessing over fractions of a stop?
I just want to make sure I know where 800 and 1250 are which seems pretty obviously one tick before 1000 (for 800) and the tick between 1000 & 1600 for 1250 (Tri-X in Diafine).
