Surge protector necessary?
Some help and advice from the electronically minded please!
I noticed today that my prints, exposed for the same length of time, were not consistent. I realized that it was due to the heater kicking in. My darkroom is in an outbuilding. No concerns in the summer - no heater. No concerns in the winter - heater going full blast constantly just to keep room warm enough to work in. Last fall we were off camping for along time - and once home spent much time developing negatives taken on trip. So now the weather is starting to warm up (sorry Eastern and Prairie Canadians - I know you're still getting dumps of snow while we are getting snowdrops) and I'm realizing I have a problem - some heat needed, but not constantly. Today I dealt with it by turning heater off while doing exposures and on while selecting neg, cropping, focusing, etc. It worked, but I know I can't count on myself to remember every time, and I will blow many exposures.
When I got this darkroom setup last year it came with a surge protector. (At least I think that is what that big, heavy, rectangular thingy that the enlarger and timer can be plugged into is.) I used it at first but it made me distrust my test strips as each time the enlarger came on you could see it "power up" - the image would go from dark to bright in a fraction of a second each time. It seemed that each 2 second exposure on the test strip was actually just a bit less than 2 seconds at full intensity, so if, say 16 seconds looked good - the only way to match it would be to do 2 second increments, rather than 16 seconds. Am I making any sense? And then I'd have to take dry down into consideration too. So I unplugged it. Do I need to plug it back in, and what about the power up time - how would I compensate for that? Would the kind of surge protector power bar I have my computer plugged into do the job any better?
Thanks to anyone who has words of wisdom for me.
"that big, heavy, rectangular thingy" is probably a voltage regulator which is the device you need to maintain a consistent light level. If you notice a change of brightness, perhaps it is not working properly. Easiest way to check would be with a volt meter and watch for voltage change. A surge protector does not do the same job at all ( prevents voltage spikes from damaging electronic equipment). There should be a label on it somewhere. Sola is one manufacturer. PM me if you want.
Why are there no speaker jacks on a stereo camera?
Originally Posted by sly
Eight two seconds exposures is not the same "equivalent" as one sixteen second exposure. The 'short' exposure times provide you with an intermitency effect.. With your 2 second exposures, the lamp is having to heat, or 'ramp up" to full output of light each time it is switched 'on' while with the one sixteen second exposure it only has this "light loss" (of heat up) only the once. The end result is that your slightly shorter two-second test exposure is less than one-eighth of your single sixteen second exposure
Eight two second exposures for multiple prints will likely give you final prints that are very similar to one another... but it can make for a rather slow process.
Quando omni flunkus moritati (R. Green)
Does the big rectangular thingy have a voltmeter on it? Usually voltage regulators do, and you can watch how well and how fast it's stabilizing the voltage. You can often hear them working as well. At least the ones I've been around.
If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
Alfonso the Wise, 1221-1284
Your don't say if your enlarger employs a mains or low voltage lamp, which will have a bearing on the solution. However it does sound like your voltage stabilizer or transformer is not working properly, whichever it is. These are very expensive to repair or replace therefore consider a UPS unit (Uninterrupted Power Supply) that will be obtainable from a computer supplier. This is the next level up to your "power bar" These are also designed to smooth and maintain the power supply to computers, which are also a bit tetchy about having a constant voltage supply.
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If you only have one 15-20 amp circuit to the building, your stabilizer might not be able to keep up with the heater. If you can do it yourself, adding another circuit can be an inexpensive fix.
You don't need a surge protector.
You may need some form of voltage regulator. A "constant voltage transformer", aka "ferroresonant transformer" would probably solve your voltage dip problem. Someone mentioned Sola - that's one brand, bu there are others.
But these gadgets aren't small and they are not cheap.
I have a Vivek voltage stabilizer (model 110; 750w max.) that maintains a constant 100v output (dims the light source). I only used it for doing color printing as voltage fluctuations cause color shifts.
Last edited by panastasia; 02-17-2008 at 08:43 AM. Click to view previous post history.
"Pictures are not incidental frills to a text; they are essences of our distinctive way of knowing." Stephen J. Gould
The "thingy" is a voltage regulator. Digging around in the boxes of stuff that have come with various aquisitions I see I have 2 of them. The Omega is the big heavy one that I unplugged last summer. The other is a Vivek - smaller and lighter. Neither has a voltmeter. I guess I'll try the Vivek and see how it works for me.
KenS - If 8 2 second exposures are not equivalent to one 16 second exposure, what are test strips for? How do you figure out a final exposure? Especially if you are doing split grade, burning and dodging, to get as close as you can to those wonderful Master Prints some APUG members produce.
My power is regulated by a voltage regulator I got at a musicians supply store. My "big rectangular boxes" are simply voltage transformers (although they may erroneously be called "regulators") that convert the 110 into 24v for the enlarger lamp. They are not fully immune to voltage fluctuation.
Originally Posted by sly
If the circuit is browning because it is near its maximum, a regulator may not do the job, because there may not be enough power to go around. A UPS may be a better solution in such a case, but IDK for sure.
Test strips get you very near the ballpark, but full time exposures must be made for final tweaking (one more test strip will exposures closely bracketing the time the previous one indicated), or you need to print intermittently exactly as you did to arrive at the strip you like. How much difference there is between a full time exposure and a test strip exposure is directly relative to how many times the enlarger is cycled, and the on/off characteristics of the particular enlarger lamp.