F/Stop printing (I suck at maths)

Hi folks. I want to try my hand at F/Stop printing without buying the device (a pensioner's life demands you get things in order of priorities.... new device = less paper.... a no brainer ... ie, no device).

So, for €7 I have picked up a Kodak Projection Print Scale and accessed an adjustment table from Tom North's blog with his kindly calculated increments and subtractions:


All well and good. However, I use Fomaspeed Variant 312 matt paper which is quite fast and the exposure times offer little to play with. On the Kodak Scale instruction sheet it is suggested that for possible short exposures it is advised to cut the test exposure time from the standard 60 seconds to 30 seconds. Cool idea... now the science bit... I truly suck at maths and even with the formula to recalculate in hand I would have no idea how to apply it. Perhaps... just perhaps it's as simple as halving the -/+ times on North's scale, but as the Inverse Square is involved it may not be as simple as that.

Any takers?

ps I have a bad dose of the flu and I am sure I'd feel loads better if someone could help me out.

Step 1: use the Kodak Projection Print Scale for 30 seconds, and then pick the right segment in your test;
Step 2: use 1/2 the time indicated on the scale as your starting exposure;
Step 3: Either use the table provided by Tom North to make adjustments from that half value, or use the more comprehensive table provided by @RalphLambrecht in his excellent "Way Beyond Monochrome" book.
Ralph has shared that table here a few times. I'll see if I can attach it to this post.

MattKing said:

Step 1: use the Kodak Projection Print Scale for 30 seconds, and then pick the right segment in your test;
Step 2: use 1/2 the time indicated on the scale as your starting exposure;
Step 3: Either use the table provided by Tom North to make adjustments from that half value, or use the more comprehensive table provided by @RalphLambrecht in his excellent "Way Beyond Monochrome" book.
Ralph has shared that table here a few times. I'll see if I can attach it to this post.

Click to expand...

So very much obliged Matt. A thousand thanks, and suddenly my flu seems quite a bit better.

I've done it for years with Ralph's table pinned to the wall next to the enlarger.