I had to go back to page one and read the OP's original question. I guess the thread has digressed a bit...
About using an enlarging exposure meter though: Personally, I never have and don't plan to. I don't think I would even if someone gave me one, because I'm really happy with, and fast at, determining my exposure using test strips. They cost less than the enlarging meter as well.
As for how to make the most useful test strip (one of the topics of the thread now): Using a linear timing will work just fine, but has the disadvantage that the more-dense stripes on the strip get progressively less exposure difference. Fred Picker touted his three-second test strip. He had his timer set on three seconds and just stepped on the footswitch a lot when making linear-timed test strips as well as building up exposure on prints (a good way to wear out a footswitch IM-HO).
It's pretty easy to understand that if you make a test strip in, say, three-second intervals that the exposure increase between the first strip with a three-second exposure and the second strip with two three-second exposures (six seconds total) is going to be a 100% or a one-stop difference. The next strip gets a total of nine seconds, only a 50% increase from the preceding strip. Note, however, that this is NOT a half-stop increase, rather a bit more. Adding half a stop to 9 seconds gets you approx. 8.5 seconds; close but not quite 9 seconds.
On to the next stripe, which gets 12 seconds total, a 33% increase (or just over a third stop increase; the real third-stop value would be approx. 11.34 seconds).
Subsequent stripes on the test strip get less and less exposure increase, which makes evaluating the test strip at longer exposures more and more difficult. By the time you get to 24 seconds, that stripe is only about 14% more exposed than the previous one. (FYI, that works out to just a bit more than a sixth of a stop). The difference between the 30 and 33-second stripes would only be 10%, or only about a seventh of a stop.
It makes a heck of a lot more sense to expose a test strip in progressively longer exposure intervals, preferably in a sequence that had the same exposure change between each stripe. F-stop timing does this, and if you use the whole-number sequence that Matt suggests (post #69), then there's not a real problem, especially since most photographers have the f-stop sequence memorized.
If you want to get more precise with f-stops, though, you quickly move in to the realm of fractions (e.g., f/5.6 or f/2.8) which makes calculating intermediate exposures a bit trickier. Plus, who has the f-stop sequence memorized in 1/6-stop increments? I know I don't. If you go down the rabbit hole of actually calculating the intervals, then you need to deal with roots of 2 and need a calculator or a fancy f-stop timer.
I prefer to work with percentages. They are easy to figure in your head and do the same job as f-stops. 10% of a 20-second exposure is two seconds; 5% is one second, 2.5% is half a second, at which point you are making an undetectable change to your print, or one that could be more easily controlled by increasing your print development time a bit.
As for test strips, I like a strip in 30% increments as follows (in approximate values).
To get total time: --- 10 --- 13 --- 17 --- 22 --- 29 --- 38 --- 49
Add a strip with: -----10 ---- 3 ----- 4 ---- 5 ----- 7 ----- 9 --- 11
I always start with 10 seconds, and just have to remember "3 - 4 - 5 - 7 - 9 - 11." I've got this posted by the enlarger too. If you want different increments, say 20%, or 25%, they are easy to figure too.
Then, when making changes to a print exposure, I'll add or subtract a percentage. Say I've found that my 22-second stripe is too light and my 29 second strip is a bit dark. I'll start with an intermediate value, say 27 seconds, and make a print. If that's still a bit off, say a tad too dark, I'll subtract 10% or so. 10% is 2.7 seconds, I'll round that to 3 seconds and make a print at 24 seconds. Or maybe I'll only need a small change, approximately 5%, but I don't waste time calculating with fractions of a second, I'll just take half of that rounded-off 10% value, or 1.5 seconds. But that pesky half-second won't make any real difference to a print exposure that long, so I'll use a change or either one or two seconds depending on which way I want to tweak the print. I don't need to get any more precise than that for black-and-white printing as far as exposure times go. If I really need to make smaller changes to a print than 5% or so, I'll do that with development time.
All this is really easy to figure in your head when working; a lot easier than calculating what a 1/6-stop change for a 27-second print exposure would be unless you've got an f-stop timer handy. I don't, I use a metronome. I like low-tech.
I found it easy to get used to visualizing what a percentage difference will look like when printing. One would have to do the same with f-stop timing too, since changes in print exposure do not correlate to the typical change in film exposure for a given f-stop value.
So, for the OP, and with all due respect to those who find f-stop timing a good tool and own f-stop timers, I recommend making test strips in intervals that increase by a given percentage and not bothering with enlarging exposure meters for the time being. They certainly aren't necessary for doing even the finest work, and not needed to sart making good prints right away. The better tools are a good understanding of how the process works and patience.
Best,
Doremus
