Compensating Timer Vs. Cold Light Stabilizer

[aduncanson]

In an embarrassment of riches, I find myself with both a Zone VI Cold Light Stabilizer and an RH Designs StopClock Vario (compensating) timer for use with my Zone VI cold light. While I will certainly use the timer as a timer, I wonder what are the trade-offs between the two approaches to stabilization and why I might choose to use one device over the other.

Naively, I prefer the idea of stabilizing the light output and keeping time "normal". But I believe that Zone VI abandoned the stabilizer product for the compensating timer. That might have been for purposes of cost savings or for performance advantages. Any ideas?

Thanks - Alan

[Donald Miller]

So far as I remember Zone VI did not replace the stabilizer with the compensating timer. The compensating timer that I have was to compensate for variations in developer temperature for negatives and prints.

The stabilizer that I have uses a sensor that measures light output and stabilizes the cold light to arrive at consistent print times. I have no knowledge of the StopClock Vario...perhaps it serves the same purpose as the Zone VI stabilizer...but I am not certain about that.

[Larry Gebhardt]

I imagine both methods work very well, but have never used a cold light head so my opinion on that isn't worth much. If both can give repeatable results I would vote for the StopClock vario, assuming it is an fstop timer like all the other RH Designs products. I love f stop printing with my RH Designs stop clock.

[John Bowen]

Alan,

I believe Zone VI switched to the compensating timer because THAT technology could be used with any size head. The Stabilizer worked great with 4x5 and smaller cold lights, but as the size of the head grew, so too did the size of the transformers to drive the head and thus the size of the stabilizer. I remember seeing a photograph of Ansel Adam's CUSTOM Stabilizer. It was HUGE in comparison. As Zone VI started manufacturing 5x7 and 8x10 VC heads, they likely realized they needed another solution to control exposures, thus the compensating enlarging timer.

Don,

Zone VI made both a compensating development timer AND a compensating enlarging timer. I have both, along with a stabilizer.

[Michael Jones]

The Zone VI "Tik Tok" as it was known was a compensating "timer" using a photocell to monitor [any] light output and produced a beep at a constant interval based upon the cell reading. As you may recall, Fred used a metronome [as did Ansel] to time printing light exposures and printed in 3-second "bursts," as he called them. His improved electronic metronome, the Tik Tok, would beep in accord with the lamp output. After testing, you could adjust it to mimic one second. When you turned on the lamp, each beep represented the same light output and compensated for warm up, age, etc.

In my experience, they are quite handy, small, and accurate with any [non-UV] light source. I have one in use and at least one other stored for when this 20-year-old one dies.

Mike

[Chuck Pere]

One thing a stabilizer can do that a compensating timer can't is vary the lamp intensity. If that's important to you. It would be interesting to test both to see which produced the most consistent prints. Try exposing say 10 sheets of paper one right after the other. Process them together and see if they match.

[Eric Woodbury]

The stabilizer suffers from several issues. First and already mentioned is that as the lamp gets larger, so does the electronics. Second, the stabilizer doesn't work with all light sources. It was designed for coldlights, but if you were using something else, it may or may not have worked. Third, by virtue of the way a stabilizer works, the lamp is never operated at maximum brightness. There must always be room to for the electronics to do the regulation, called headroom.

These issues 'forced' the invention of the MetroLux compensating timer in 1984 or so.

[Drew Wiley]

I too am somewhat skeptical of the ability of a stabilizer to predictably control the
variables of temperature or age in a coldlight. A light integrator which measures actual
output seems a lot more practical. I simply use the old Zone VI unit which beeps at
intervals of light output. It has been completely predictable and repeatable.

[aduncanson]

Thanks all. I appreciate your inputs to date. Please understand that the Zone VI Cold Light Stabilizer uses the same light sensor as the compensating timer and presumable adjusts the voltage or current to the lamp to achieve constant light output.

- Alan

[Eric Woodbury]

Alan

a small correction, perhaps insignificant. It is not clear which compensating timer you mean, but the compatibility is the other way around. The MetroLux timer and, probably you mean, the Z6 timer can use the same sensor as the Z6 Stabilizer. The Z6 Stabilizer is not compatible with the sensor used in the MetroLux. I'm not familiar with what RHD is using.