Grade change time

[RalphLambrecht]

As Nicholas said, it depends on the print tone that you want to keep constant. Filter kits are typically calibrated to give the same exposure for the ISO speed point; a tonality too dark for calibration across paper grades in my opinion (see 1st attachment). You have to pick a tone, because the characteristic curves between grades differ (otherwise it would make no sense to switch grades). I advocate to expose prints for the highlights, so I pick a lighter tone (Zone VII or VIII). As others said, yes, it's best to test for your conditions.

However, you don't have to make a test strip every time. You can conduct one test and make yourself a table (see 2nd attachment), which is good for one particular paper/developer combination. Once you have the table at hand, you can convert a proper highlight exposure of one grade into another for another grade with ease.

[bwrules]

Thanks all. Really appreciate the information.

[BetterSense]

This is part of the reason that I used to use split-grade printing with only 00 and 5 filters. I've kind of stopped doing that because #2 just works for most of my negatives, but any time I need to make a contrast adjustment, I always wish I had started with the 00 and 5 split grade technique, because it's easier to vary the proportions of exposure without changing the actual filters you are using. By the way, is there any H&D curve difference between using 00 and 5 filters versus using the equivalent single exposure with an intermediate filter?

[RalphLambrecht]

... By the way, is there any H&D curve difference between using 00 and 5 filters versus using the equivalent single exposure with an intermediate filter?

By using the two filter extremes for split-grade printing, you can produce the same characteristics curve as any intermediate filter. There is absolutely no tonal advantage to split-grade printing if you simply add the two exposures. You will, however, get a benefit if you dodge and burn differently with both filters.