I think we're talking about an 80 second exposure here, not 80 minutes, which is not all that uncommon with larger prints (still long, though).

Monochromefan,

F-stop timing really works better with and f-stop timer, which has settings in stops and fractions of stops. Otherwise, you need to use the conversion charts.

If you want the logical spacing of f-stop timing without the timer or the conversion chart, just use percentages. That's what I do. Test strips are usually in 30% intervals (I don't think you'd get useful information from a test strip in full stops or 100% intervals; the spacing between exposures is just too great).

I like exposures in the 15-30+ second range. I time with a metronome and count seconds, so I make test strips by sequentially covering stripes of the test strip after an initial base exposure. My (approximate) 30% test has these final exposures: 10 sec., 13 sec., 17., sec., 22 sec., 29 sec., 38 sec. That means I start the exposure, count 10 seconds and cover the first stripe, count 3 seconds, cover the next, etc. The counting sequence is easy to remember after a time or two: 10 - 3 - 4 - 5 - 7 - 9.

If that's not enough exposure, then I'll open up a stop or adjust the light intensity and make another test strip. I'd only use base exposures longer than 40 seconds or so If the print were really large and needed longer exposures or if the negative were really dense and I didn't have enough light, even only closed down one stop. In that case, I simply double the strip timing to 20 - 26 - 34 - 44 - 58 - 76 (count: 20 - 6 - 8 - 10 - 14 - 18).

When printing, make exposure adjustments as you need and dodge and burn as needed, but think in percentages of the base exposure (e.g., dodge 10% here, burn 70% there, etc.). After a while, you get a pretty good idea of how much x% exposure change makes. Keep in mind, however, that all this is contrast-grade dependent (even with f-stop timing). A 2/3-stop increase in exposure is about that same as adding 70%, but that much extra exposure makes a smaller change in print density at grade/contrast setting #1 than at grade/contrast setting #4.

Keeping track of print manipulations in percentages is helpful when you make a different size print. Once you establish the base exposure for the new print size, you can then easily figure the timing of dodges and burns, which should get you in the ballpark (I find that different-size prints often need a bit different treatment, so those times are always just a starting point for me).

Hope this helps,

Doremus