Timer Tester

Going over the timers I aquired, it looks like one may be off a bit. Finding an accurate AND trustworthy souce of time is easier said than done. It got me thinking about a solution.

A small box that plugs into the enlarger outlet on the timer and starts counting, with 0.01 second resolution up to 99.99 seconds, when the circuit is energized. Obviously it would stop counting when the circuit is turned off.

This could also be used to check shutter calibration as well. A way to change the time scale to one with 0.0001 seconds resolution and different adaptor and it should work for that.

Does anyone think that this would be commecially viable? If so, would you buy one? How much would you pay? What would be an acceptable margin of error?

I'd buy a shutter tester, but I don't feel I need to test my enlarging timer. I'm not sure why the tester would necessarily be more accurate than my Metrolux (even if I were using it as a regular timer, rather than as a compensating timer), and I could easily enough check my Omega Pro Lab timer against something else.

I have a shutter tester (Thomas Tomosy - forget the brand name). It works well. While a stop watch is probably all I need for the darkroom, I have a number of much more accurate and precise timers. I just don't need anything better. I would be surprised if anyone does. I am usually wrong. On that you can depend. By the way, if Mr. Callow is reading this, I believe Mr. Tomosy lives (or lived) quite near you.

Cheers,
Clarence

CRhymer said:

I have a shutter tester (Thomas Tomosy - forget the brand name). It works well. While a stop watch is probably all I need for the darkroom, I have a number of much more accurate and precise timers. I just don't need anything better. I would be surprised if anyone does. I am usually wrong. On that you can depend. By the way, if Mr. Callow is reading this, I believe Mr. Tomosy lives (or lived) quite near you.

Cheers,
Clarence

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Where abouts? Detroit, Ferndale, Birmingham or is he out here in Vancouver?

Vancouver, he is still in the phone book. I have never met him, but I looked into taking one of his courses - he had recently retired (that was about 5+ years ago). I bought the tester from him a few years ago. The manual for the (now discontinued) tester is still on-line at:

http://cameratester.homestead.com/index.html

It works very well.

Cheers,
Clarence

CRhymer said:

I have a shutter tester (Thomas Tomosy - forget the brand name). It works well. While a stop watch is probably all I need for the darkroom, I have a number of much more accurate and precise timers. I just don't need anything better. I would be surprised if anyone does. I am usually wrong. On that you can depend. By the way, if Mr. Callow is reading this, I believe Mr. Tomosy lives (or lived) quite near you.

Cheers,
Clarence

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I certainly understand where you are coming from, but I am looking at it from a bit of a different angle.

(I am going to use easy numbers here.)
Purely as an example, let's assume that a given time is over by 10%. If a exposure is set for 10 seconds, in reality it will 11 seconds. In my notes I take down that a print comes out how I want it at 10 seconds, at f11 with a column height of 8 in. Hours have been spent determining this, as have countless test strips. If I need to make another print, I have already done all the leg work

A few years later, I have a need to remake the print. By this time, I have bought a new time for whatever reason. This timer, however, is under by 10%. I go to make the print, setting the timer for 10 seconds. When I develop the print, it comes out way too light. Now, I have to repeat the process of determining what the proper exposure is and the wonderful process of trial an error.

Maybe it is just the engineer in me, but I want to have all of the variables know so that I can compensate properly. I know there will always be things that you cannot compensate for (bulb output over life, etc). By knowing the operating error of the timer, I can make two different timer with different amounts of error resonably identical.

I enjoy the process of finding out what combination of factors makes the best print, but I am lazy and do not want to have to repeat it. Same goes for the Word doc I was working on and the computer crashed, loosing all of my work. Yeh, I will have to recreate it, but it will not be the same, I will not put the same effort into it, it will be different.

Just my $0.02 worth, your miliage may vary.


Jason

I have a shutter tester (Calumet) and that's about as precise as I'm going to get. When it gets to timing the timer I walk away.

schwefel said:

I certainly understand where you are coming from, but I am looking at it from a bit of a different angle.

(I am going to use easy numbers here.)
Purely as an example, let's assume that a given time is over by 10%. If a exposure is set for 10 seconds, in reality it will 11 seconds. In my notes I take down that a print comes out how I want it at 10 seconds, at f11 with a column height of 8 in. Hours have been spent determining this, as have countless test strips.....

Maybe it is just the engineer in me, but I want to have all of the variables know so that I can compensate properly. I know there will always be things that you cannot compensate for (bulb output over life, etc). By knowing the operating error of the timer, I can make two different timer with different amounts of error resonably identical.....

Jason

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Jason,

I too, have a background in engineering and acknowledge the fact that we engineers tend to exaggerate problems we need to solve. It's how we impress others - it's a very competitive profession.

The truth is: making another (future) test strip is far easier than you make it sound. We're talking about a few minutes for a single test, not hours, and I belive timers all work with reasonable accuracy for darkroom work, especially the compensating type.

I'm not trying to be a wise ass, I'm only being realistic for those who are new at this.

Regards,

Paul

panastasia said:

Jason,

I too, have a background in engineering and acknowledge the fact that we engineers tend to exaggerate problems we need to solve. It's how we impress others - it's a very competitive profession.

The truth is: making another (future) test strip is far easier than you make it sound. We're talking about a few minutes for a single test, not hours, and I belive timers all work with reasonable accuracy for darkroom work, especially the compensating type.

I'm not trying to be a wise ass, I'm only being realistic for those who are new at this.

Regards,

Paul

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Paul,

I know exactly where you are coming from. I will say though, once I get something perfect, I want it to stay that way. I know doing the test strips are easy.

As an aside, such a device would also test the repeatability of a timer. A timer that is 10% out of whack is easy to compenste for. One that varies between -10% and +10% is whole different animal.

That is why I posted on here. I think it is a good idea to me. It is not a good idea, however, if it is not commecially viable. At least not to anyone but myself.

Jason

schwefel said:

Paul,

One that varies between -10% and +10% is whole different animal.


Jason

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10% error is outrageous for a precision timing device. Do you mean 1.0% error? My timer reads in 1/10th sec. increments, and the time interval will change as the light intensity changes (compensating). 10% error would put a company out of business very quickly.

I'd have to think that variations in bulb output and color temperature, filter aging, and paper lot to lot variation will matter much more than variations in a timer that is either crystal controlled (any microprocessor controlled timer) or line frequency controlled (gralab 300-type).

A light meter (Ilford EM-10, or one of the high end timers with a light sensing) will allow a basic compensation for those changing parameters. When I do use anything but test strips, I use an EM-10 to get close on the first print, but there is still plenty of testing and tweaking to get a print that I am happy with the second time. I am sure the combined meter/timers are more convenient, but the EM-10 works and is cheap.

panastasia said:

10% error is outrageous for a precision timing device. Do you mean 1.0% error? My timer reads in 1/10th sec. increments, and the time interval will change as the light intensity changes (compensating). 10% error would put a company out of business very quickly.

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10% was mearly being used as an easy example

That being said, picking up an item used, you do not know what you are going to get, how it was treated, etc.

I agree with Jon King on this one. If you come back to a negative a few years after printing it these days, the paper will be different, your developer might be different, and you will be different, and you might interpret the negative differently, even if you thought you wanted it to be the same at first. This is part of the reason I'm skeptical about "editions" of photographs, particularly if the entire edition isn't printed at one time.

timer quality

Fred Picker used to tell us that when you make a print none of the variables will EVER be the same....as mentioned in previous posts plus the fact of the time of year;water; temp;and whatever else is going on...to actually assume that you can go back to the original conditions is ridiculous....on the other hand when I go back and redo prints they usually end up to be better than the original...go figure!!
Best, Peter

The thoughts that come to me...

I like the concept - perhaps not for all the reasons you have come up with. I'm not sure an accurate and precise darkroom timer will control enough variables to save me much future work.

Let's see... developer strength, solution temperature, paper formulations change over time and papers get discontinued, voltages vary, new bulb in enlarger, slightly different enlarger height, hard to set aperture to exactly same opening, close yes, exact ummm, agitation of paper in developer, how much unintended flashing happens when safelight that's maginally safe just barely exposes enough to bring image a bit closer to threshold, age of enlarging paper, any marginal exposure to sulfide fumes etc ... There are a lot of variables.

Nonetheless, I'd take a look at a timer such as you describe - if the control set doesn't require a post doc.

I have taken a quick look at a couple of other timers - not as much of a look as they deserve mind you - but I was left with the impression I would end up using only the top 5% of the functions because the rest would fade from my memory from just a bit too much complexity.

I'm no luddite. I do some VB database design for fun. But I like my tool controls intuitive. My own limited experience coding / designing leads me to believe it is a very different experience to use a device one has designed one's self, than trying to use someone else's design.

Regardless, the thinks I'd look for:
I'd like a timer that reads accurate and precise in chunks of .1 sec to 99 sec.
I'd like a solid shutter tester.
I'd like a timer that allows me to easily control two channels for blue and green lighting for variable contrast papers.
It would be a huge plus to have four channels to also allow controlled flashing on VC paper.
Audible cues for burning and dodging?

Thanks for reading this,

C

CBG said:

I have taken a quick look at a couple of other timers - not as much of a look as they deserve mind you - but I was left with the impression I would end up using only the top 5% of the functions because the rest would fade from my memory from just a bit too much complexity.

I'm no luddite. I do some VB database design for fun. But I like my tool controls intuitive. My own limited experience coding / designing leads me to believe it is a very different experience to use a device one has designed one's self, than trying to use someone else's design.

Regardless, the thinks I'd look for:
I'd like a timer that reads accurate and precise in chunks of .1 sec to 99 sec.
I'd like a solid shutter tester.
I'd like a timer that allows me to easily control two channels for blue and green lighting for variable contrast papers.
It would be a huge plus to have four channels to also allow controlled flashing on VC paper.
Audible cues for burning and dodging?

Thanks for reading this,

C

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Not that is interesting.

I guess I did not think of the angle, "Why test the time, why not build a better timer"

What you suggest it quite doable.

If for not other reason than I do not have a new house to build a darkroom, I will play with that idea instead.

Here are my thouhgts, based on what you posted:
Quartz timing
2 - 4 digit readout banks
push buttons for setting time (cycle through 0 - 9)
One outlet each: Blue, green, safe light, flasher
burn/dodge beep (timescale?)
Shutter test

Anything else? Not asking for the kitchen sink, though. Control layout would be simple and intuitive.
Not to say it would be easy, but we are not talking terrible difficult, either. Even with what little I remember of electronics, I should be able to put together something workable.

> I'm not sure an accurate and precise darkroom timer will control enough variables to save me much future work.

It's not what it controls but how it lets you control it.

> developer strength, solution temperature, paper formulation, agitation ...

It is possible to get identical prints over long spans of time. The hard variable to control is the gradual shift in paper contrast over time.

Precise metering and voltage regulation are key. You can do without a regulator if you print late at night or in the middle of the afternoon when voltage is stable.

Naturally, fresh developer, reasonably constant temperature and timed development are also required.

> I'd look at a timer ... if the control set doesn't require a post doc

I don't know of any post-docs in Darkroom Automation's customer base. A few retired MD's. A _lot_ of retiring professionals printing a final portfolio who are in need of something to make the job go faster (and better and cheaper) -- they tend to be a flinty no-BS crowd.

> I was left with the impression I would end up using only the top 5% of the functions

Same with everybody. Problem is everyone has a different 5%. And that 5% changes with time. For function overload I think DVD players take the cake but everyone seems to be able to get what they want out of their DVD player.

> It would be a huge plus to have four channels to also allow controlled flashing on VC paper.

Now there is a first -- a unique 5%. Should the channels track as two sets of two or as one set of four? If it as two sets of two channels with optional tracking within each set then I have just the timer for you.

On the subject of timer errors:

• The timers most prone to error are the psuedo-digital ones with a pair of 0-9 knobs. The biggest errors are when switching decades, as in 19 seconds to 20 seconds. They also suffer from noise in the switch contacts and can be erratic - Radio Shack contact cleaner usually fixes the eraticity.
  
• GraLabs and their kin are prone to two errors: You can't set them to much better than 1/3 second; Each exposure is off by a fixed time amount because of the switch/clockwork mechanism. As a result five 2-second exposures rarely equal one 10-second exposure, and test strips are often iffy.
  
• Many digital timers use an RC time-base and may have a 1% constant fast/slow error. This will have no real effect on exposure as the error is repeatable and 1% is about 1/70th of a stop.

Nicholas Lindan said:

> I'm not sure an accurate and precise darkroom timer will control enough variables to save me much future work.

It's not what it controls but how it lets you control it....

Precise metering and voltage regulation are key. You can do without a regulator if you print late at night or in the middle of the afternoon when voltage is stable.

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The information that came with my old GraLab 400 series (analog type) timers advises against using voltage regulated current - they wont work properly.

panastasia said:

The information that came with my old GraLab 400 series (analog type) timers advises against using voltage regulation.

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Analog timers have synchronous AC motors in them and these may have trouble with the two most common forms of regulation:

• Ferroresonant transformers put out a square wave that may give some motors problems. 'Harmonized'/CVS ferros put out a sine wave that should work OK with any timer.
  
• Solid-state regulators put out a chopped AC or DC waveform that, again, will give many synchronous motors the fits.

You can use both of these regulators if you put them between the timer and the enlarger.

The motors in drills and most appliances are 'universal' motors that don't care what sort of power they see. Fans use induction motors that, like synchronous motors, want to see well behaved AC.