Darkroom program

measwel

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For those who would like to take their darkroom into the 22 century:

Darkroom

A program for automated darkroom control using smart devices. As I am the author, I would welcome all feedback. This is what the program currently looks like in practice:

FStops.JPG
 
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Hi,

I have uploaded a new version of the program, which should work without any smart devices set up. So the user can try it out. The only condition is to have python on the computer and import the needed dependencies as explained in the README.

 
I got the light intensity sensor today. Some suprising results.

Good: it works :).

Strange: with a opal light bulb the measurement is linear. Changing 1 stop on the lens halves the measured lux value. I also tried a LED bulb. In this case the measured values did not quite get halved, but it was close enough to be practical I guess.

Interesting: a cold white light gives more measured lux than a warm white light at the same brightness setting.

Bad: the sensitivity of the sensor is on the low side. The scale goes from 0 to 1000. With an average setting on my enlarger (20 x 20 cm print, F5.6) I am getting a reading of 16 lux. Making a big print or closing down the lens to F22 will bring the measured value to 0 lux.

Conclusion; it is sensible to use the strongest bulb feasible in the enlarger head. I will try with the stongest LED bulb I can find.
 
Like a lot of 'gadgets' they may make, you think that it helps - but I find the more 'simplifying' technology you get which can take your mind of what you are doing I.E. printing. This can be counter productive because you become too involved with the 'help' that you start worrying in case the technology isn't doing it's job instead of gaining experience when you by instinct know when things are right and will produce the results.
My tech is a good thermometer, timer and a safelight that does exactly as it should. Oh yes add in a few graduated beakers.
 
Like a lot of 'gadgets' they may make, you think that it helps - but I find the more 'simplifying' technology you get which can take your mind of what you are doing I.E. printing. This can be counter productive because you become too involved with the 'help' that you start worrying in case the technology isn't doing it's job instead of gaining experience when you by instinct know when things are right and will produce the results.
My tech is a good thermometer, timer and a safelight that does exactly as it should. Oh yes add in a few graduated beakers.

I agree, the basic necessity is a thermometer and a timer. My application's main function is exposure timing - based on seconds and F-Stops. The F-Stops timing is quite handy - some consider it superior to seconds based timing, especially when making teststrips. The automatic exposure time calculation and switching the darkroom lamps on and off is just a nice-to-have. I find it useful, but not essential.

What are graduated breakers?
 
I agree, the basic necessity is a thermometer and a timer. My application's main function is exposure timing - based on seconds and F-Stops. The F-Stops timing is quite handy - some consider it superior to seconds based timing, especially when making teststrips. The automatic exposure time calculation and switching the darkroom lamps on and off is just a nice-to-have. I find it useful, but not essential.

What are graduated breakers?
Another essential - a measuring beaker either in CC's or fluid ounces to measure out quantities of fluids.

I sometimes use the F stop adjustment for printing, but I have a chart with the times and the difference between each 1/4 stop. Apart from that my most complex bits of kit are my electronic thermometer which I bought in 1982 and my electronic timer for the exposures
 
I use a stop clock for this I bought it from RH systems from his house in Hemel Hempstead about 30 years ago not sure if you can still buy them or not but it is a handy item.
 
I use a stop clock for this I bought it from RH systems from his house in Hemel Hempstead about 30 years ago not sure if you can still buy them or not but it is a handy item.
I Think RH Systems is now owned by Second Hand Darkroom Supplies but they are now very expensive. The original designer was last living in Hawes, Wensleydale, North Yorkshire when I bought one from him direct in around 2003. He was still a one man band then. I could not get along with it so sold it after about 3 years.

I Have just checked the SDS website and they are £469 new. You can buy an awful lot of paper and film for that price.
 
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I Think RH Systems is now owned by Second Hand Darkroom Supplies but they are now very expensive. The original designer was last living in Hawes, Wensleydale, North Yorkshire when I bought one from him direct in around 2003. He was still a one man band then. I could not get along with it so sold it after about 3 years.

I Have just checked the SDS website and they are £469 new. You can buy an awful lot of paper and film for that price.
Yes a simple timer will get the job done - I must confess to enjoy using less and less of everything these days.....
 
I got the light intensity sensor today. Some suprising results.

Good: it works :).

Conclusion; it is sensible to use the strongest bulb feasible in the enlarger head. I will try with the stongest LED bulb I can find.
I may be wrong but the light emitted by an LED bulb may well upset the values of filters when printing both B&W and colour. Also when I did try one in a Durst M600 my timer did not like it and instead acted like a repeating strobe so if the timing was say 5 seconds in those 5 seconds it would flash about 25 times. I never tried it again although the timer 'died' and I replaced it with a newer one.
The only LED I have in my darkroom is in an anglepoise lamp because the Light output is 6750K a more accurate colour temp for judging colour print balance
 
I may be wrong but the light emitted by an LED bulb may well upset the values of filters when printing both B&W and colour. Also when I did try one in a Durst M600 my timer did not like it and instead acted like a repeating strobe so if the timing was say 5 seconds in those 5 seconds it would flash about 25 times. I never tried it again although the timer 'died' and I replaced it with a newer one.
The only LED I have in my darkroom is in an anglepoise lamp because the Light output is 6750K a more accurate colour temp for judging colour print balance
For black and white printing you need a "Warm White" LED bulb rated 2800K. This has the same colour temperature as the old incandescent bulbs so multigrade contrast filters will work exactly the same.
 
For black and white printing you need a "Warm White" LED bulb rated 2800K. This has the same colour temperature as the old incandescent bulbs so multigrade contrast filters will work exactly the same.
I completely agree, however what I remarked was not a question or a statement it was just another point to note about LED light sources
 
For black and white printing you need a "Warm White" LED bulb rated 2800K. This has the same colour temperature as the old incandescent bulbs so multigrade contrast filters will work exactly the same.
I confirm. Just tested the ledvance 2700K, 2500 lumen opalized glass LED bulb.

Just short of 12 cm in length, it fits fine in the Durst M601 head. 2500 lumen rock. With a fairly dense negative, I need about 12 seconds at F5.6 (componon-S) for a very respectable 30 x 30 cm enlargement. The lighting is even and Ilford contrast filters work totally normally. 25000 hours lifespan, almost instant full brightness and almost no heat production. In my opinion, an excellent bulb for black and white work. I have yet to notice any downside.
 
What does not work as I hoped is the tuya light sensor. It is not sensitive enough to make reliable exposure time calculations based on the reading. On a scale from 0 to 1000 lux, I am getting anywhere from 0 to 6 lux at the 30 x 30 cm enlargement, depending on what part of the negative I measure on the baseboard. That is unfortunately not enough to calculate the time sensibly.

So I changed the application to just give an approximate base time for a given paper and enlargement, so one can start from there.
 
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