- Sep 2, 2006
- Cleveland, O
- Multi Format
That is all "f-Stop" timing is. If you use 7% steps it equates to the 1/10 of a stop of modern f-Stop timers. 25% steps are .32 stops apart (1/3 of a stop for all intents and purposes) - a convenient interval for a test strip.Personally, I use percentages...
f-Stop timing is a really bad name for the technique. I confess to promulgating the name - I should have thought up something better. In using the DA and other 'pure' timers you never see the f-stop sequence, just 2.0, 2.1, 2.2...
I imagine it all started with someone taping a lens f-stop chart to the wall and using the sequence as exposure times. The standard lens f-stops yield 1/2 stop changes in time, 1/2 stop intervals yield 1/4 time stops, and 1/3 stop intervals for a lens (f2.8, f3.2, f3.5, f4.0) yield 1/6 time stop intervals.
If I didn't have an f-Stop timer handy I would have looked at the technique and said "Hey, pretty cool, I guess" and then I would have promptly gone back to seconds. But as I do have an f-Stop timer handy I would never consider plugging my enlarger into a linear timer. And I think that goes for all f-Stop timer owners.