F-Stop Printing Calculators. now I am confused

[Steve Goldstein]

[snip]
FWIW, the smallest change I can regularly detect in print exposure amounts to about 3%. Less than that and I'm not really sure. I'll let you f-stop guys figure out how much of a stop that is. (Someone will now certainly make a table with percentages to f-stop equivalents... I see it coming )

Best,

Doremus

3% is about 1/24 of a stop, which perhaps not by coincidence is the minimum increment in the "Darkroom" f-stop timer app on my iPhone.

 

[RalphLambrecht]

+1but no table for Doremus.He does not need it.Incidently,I consider 1/12 stop a minute 1/6 stop o moderate and 1/3 stop a significant image alteration,which is roughly equivialent to 5,10 and 20%modifications;stops or percentages,six of one or half a dozen of the other...

 

[Nicholas Lindan]

10% intervals are insanely easy to calculate...

Oh, man - 10% is, lets see ln(1.1)/ln(2) = 137.5E-3 stops - I'd like to say I can do that in my head, but I can't. So if my time is 3.4 stops and I want to decrease it by 10% my new timer setting would be 3.4 - 0.137 = er, calculator please, I got it = 3.262 stops. Now what is convenient about that? (Insert smiley if you feel the need of one.)

The problem with percentages is that they don't add. A 50% increase twice over gets you a 125% exposure increase - not 100%. That doesn't make much difference if the adjustments are small - 2 x 10% = 21% - but if the changes are large - say changing print sizes or making part of an exposure adjustment with the aperture - things get a bit sticky.

Enlarging timers should have never ever been marked in seconds.

God did not create the integers - he created the logarithm. Silly little Man, who can only count on his fingers, created the integers. I mean, "And God Said 'Go forth and add'"??? And Hawking gets it wrong, yet again.

 

[Nicholas Lindan]

I still can't figure out why the U.S. has never embraced the metric system. That said, no one I know is better at adding fractions than an American carpenter...).

Well, one reason is that America is populated by people who left Europe in disgust. Generally, if Europe goes one way then America will go the other just on general principles.

As for carpenters -

1/2 - 1/4 - 1/8 - it's binary. It's easy. It makes a lot more sense than 1/10th and 1/100th.

I understand housing in Europe uses 60cm as the base dimension for sheets of plywood and stud spacing. Even metric doesn't embrace metric ...

 

[Truzi]

Well, one reason is that America is populated by people who left Europe in disgust.

Some were kicked out, lol.

On a more serious note, I am enjoying this thread. I've wanted to try f-stop printing.

 

[JackRosa]

+1 for RH Designs' StopClock. Not inexpensive but worth every penny. Not sure whether you can find Darkroom Automation (Nicholas') equipment in Europe. I have one of his enlarging meters and love it. Don't have one of his f-stop timers but would think they are that yu would also receive good customer support.

 

[Steve Smith]

I understand housing in Europe uses 60cm as the base dimension for sheets of plywood and stud spacing. Even metric doesn't embrace metric ...

Yes... but most builders of my age will still measure it in feet and inches. At one time in the UK, timber was sold in 'metric foot' lengths of 300mm


Steve.

 

[Doremus Scudder]

Oh, man - 10% is, lets see ln(1.1)/ln(2) = 137.5E-3 stops - I'd like to say I can do that in my head, but I can't. So if my time is 3.4 stops and I want to decrease it by 10% my new timer setting would be 3.4 - 0.137 = er, calculator please, I got it = 3.262 stops. Now what is convenient about that? (Insert smiley if you feel the need of one .)

The problem with percentages is that they don't add. A 50% increase twice over gets you a 125% exposure increase - not 100%. That doesn't make much difference if the adjustments are small - 2 x 10% = 21% - but if the changes are large - say changing print sizes or making part of an exposure adjustment with the aperture - things get a bit sticky.

Enlarging timers should have never ever been marked in seconds.

God did not create the integers - he created the logarithm. Silly little Man, who can only count on his fingers, created the integers. I mean, "And God Said 'Go forth and add'"??? And Hawking gets it wrong, yet again.

Nicholas,

I get your point! And, if I needed to add increases or subtractions of exposure often, I might well embrace f-stop printing. Heck, if someone gave me one of your nifty f-stop timers I would likely switch. And, I love logarithms, but I can't do them in my head...

However, being stuck in the integer world when printing (using a metronome that only counts seconds) I find it easier to use percentages.

FWIW, Oh, man - 10% is, let's see: 10% of a number of seconds is just a shift of the decimal point. 10% of 30 seconds is 3 seconds, so 10% more than 30 seconds would be 33 seconds. I CAN do that in my head. (here's a smiley face already inserted )

If I have to add 50% and then give 50% more time, I'll just use the total time as a percentage of the base exposure. (12 + 50% = 12+16=18; 18 + 50% = 18+9=27. That's 15 seconds more than the original base exposure or 125%. I can do that in my head too...)

So, I'll remove tongue from cheek and just "go forth and print."

Best,

Doremus

 

[polyglot]

There's clearly some confusion about why we use f/stop timers. Would there be value in me creating a detailed video of how one is used and the benefits it gives?

If so, what do you (as an experienced f/stop printer) think should be in it or alternatively what do you (as someone who thinks God Invented Seconds Dammit And Why The Overcomplication) want to see explained? Obviously the video will be made on my open-source timer, but I'm sure everything that it can do can also be done with the RHD and DA timers.

 

[TheToadMen]

Does anyone have a used Darkroom Automation f-stop timer or a RH Designs StopClock Professional f-stop timer for me?

I would like to see if the f-stop system will work for me. I read about it and I think I can use it to make better prints.
But I haven't got such a timer and a new one from SDS is too expensive for me.
And borrowing one for a few months doesn't seems like an option overhere, since I don't know anyone who has got one lying around.

Thanks,
Bert from Holland

 

[miha]

Bert, did you watch the tutorials on the RH site? Very helpful.

 

[TheToadMen]

Bert, did you watch the tutorials on the RH site? Very helpful.

Yes I did (some) and makes me want to try it even more. I even recognized the DeVere wall mount (4x5 ?) enlarger. I have got the DeVere 4x5" and the 8x10" enlargers (saved from scrapping), but no StopClock to accompany it yet ...
So for now I'll settle by getting out my book "Way beyond Monochrome" and read the section on F-stop printing again this weekend

 

[MartinP]

TTM, perhaps you could print up one of the rotary-timer (like a Durst TIM60 or similar) F-stop dials on a laser printer and try that, if you can find a rotary dial timer?

I'm not 100% clear, in detail, how that would work as I usually use the table from Ralph's book on a piece of paper, or sometimes percentages, or a wild guess, depending on the need . . .