Looking to upgrade my enlarger timer

logan2z · Jun 21, 2021

Doremus Scudder said:
IThey give the same results as f-stop timing without all those pesky square roots and calculations.

The nice thing is the timer makes all the calculations, you don't have to. That said, while I've become accustomed to using an f-stop timer and thinking in that way, use of one is certainly not a necessity.

awty · Jun 21, 2021

I printed a f stop chart in A3 laminated and stuck it to the wall next to the enlarger. No need for any calculations, makes it easy to adjust exposures.

http://twelvesmallsquares.blogspot.com/2013/05/

MattKing · Jun 21, 2021

My that chart looks a lot like the chart in Ralph Lambrecht's book, Way Beyond Monochrome .
See Figure 2: http://mail.waybeyondmonochrome.com/WBM/Library_files/TemplatesEd2.pdf

Doremus Scudder · Jun 23, 2021

logan2z said:
The nice thing is the timer makes all the calculations, you don't have to. That said, while I've become accustomed to using an f-stop timer and thinking in that way, use of one is certainly not a necessity.

100% = 1 stop. 70% = ~2/3-stop. 50% = 1/2-stop. 30% = ~1/3 stop. 25% = 1/4-stop. 15% = ~1/6-stop. 10% = just a tad more than 1/8-stop. Whatever fractions you want to use, there's a percentage equivalent. I'm used to visualizing exposure differences in these and even smaller increments (5% makes a real difference with a relatively high-contrast filtration).

I usually use increments of 10% so that they are easy to figure in my head. Add 20% to a 33 second exposure: EZPZ; 20% is 6.6. seconds, round up to 7 and 40 seconds is the next try (or 39 seconds if I feel I need to round down). Same learned/intuitive idea of how much time change gives how much density change without a chart, decimal places, square roots, or having to buy an expensive timer .

I'm really surprised more people don't use percentages. Heck it would be a lot easier to design a percentage timer than an f-stop one too...

Doremus

Maris · Jun 23, 2021

Doremus Scudder said:
......I'm really surprised more people don't use percentages. Heck it would be a lot easier to design a percentage timer than an f-stop one too........Doremus

Me too. I've never used anything but percentages for changes in paper exposure: easy, familiar, and intuitive. And the mental arithmetic involved is trivially simple.

Nicholas Lindan · Jun 23, 2021

Doremus Scudder said:
Heck it would be a lot easier to design a percentage timer than an f-stop one too...

Errr, no, not really. The microprocessor in the timer works in base 2. The calculations are done in base 2 floating point. Using stops or percents doesn't make much difference. Decimal fractions (ie percents) are a bit of a problem in base 2 because they are repeating numbers, like 1/3 in base 10 is 0.333333... where 1/10 in base 2 is 0.0001100110011... so you have to be careful to normalize things. In general base 10 is a terrible choice for a number system - any culture that gave some thought to the subject, rather than counting on its fingers, settled on 12/60/360. Look at a watch, a protractor, a compass; try and buy a box of 10 eggs (though I'm sure there is somewhere on earth you can).

Now an f-stop timer that works in 1/2, 1/4, 1/8 of a stop can be made with very simple software. The original Nocon timer worked this way - didn't even use a microprocessor as it was hardwired from TTL logic. The Nocon patent has the schematic.

So for a real bastardization of number bases a timer that works in decimal stops ... oh, wait, I think I know of one. Darkroom Automation made the first; it is now the standard with all the DIY designs out there.

Doremus Scudder · Jun 24, 2021

Nicholas Lindan said:
Errr, no, not really. The microprocessor in the timer works in base 2. The calculations are done in base 2 floating point. Using stops or percents doesn't make much difference. Decimal fractions (ie percents) are a bit of a problem in base 2 because they are repeating numbers, like 1/3 in base 10 is 0.333333... where 1/10 in base 2 is 0.0001100110011... so you have to be careful to normalize things. In general base 10 is a terrible choice for a number system - any culture that gave some thought to the subject, rather than counting on its fingers, settled on 12/60/360. Look at a watch, a protractor, a compass; try and buy a box of 10 eggs (though I'm sure there is somewhere on earth you can).

Now an f-stop timer that works in 1/2, 1/4, 1/8 of a stop can be made with very simple software. The original Nocon timer worked this way - didn't even use a microprocessor as it was hardwired from TTL logic. The Nocon patent has the schematic.

So for a real bastardization of number bases a timer that works in decimal stops ... oh, wait, I think I know of one. Darkroom Automation made the first; it is now the standard with all the DIY designs out there.

That makes a lot of sense. As long as the timer does all the work calculating, it should be really easy to use. If I ever feel an urge to depart from my Luddite ways...

Doremus

Hilo · Jun 30, 2021

albada said:
Why is turning off the safelight during exposure useful? The only reason I can think of is that you might be able to see the image better, helping with dodging/burning. Is there any other reason? Conserve electricity?

As someone else already said: yes, you see the projected image more clearly. Which helps with burning and dodging. Another reason to shut off your safe-lights when exposing is to make sure there won't be any fogging. I do lots of 20x24in. (50x60cm) prints and exposure times of one minute are not unusual. And then sometimes I expose again that time, to burn . . .

I have many darkroom lamps against the ceiling and close to the walls, always at least 2 meters away from the easels or the sink. Four enlargers. Two are hooked up to the same Kearsarge 301 timer and the two other enlargers each have their own timer, the same Kearsarge. The feeling that these lamps turn off when exposing is great. It gives me better concentration.

radiant · Jun 30, 2021

Hilo said:
As someone else already said: yes, you see the projected image more clearly. Which helps with burning and dodging.

Yes and one point; my enlarger timer also puts on the enlarger red light before exposure (for five seconds) which makes doding/burning easier because you know where to start with the tool. Because of that the ceiling light must be turned off to see the "red" image on easel.

Looking to upgrade my enlarger timer

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