calibrating Metrolux with Aristo hi intensity bulb

**Ken Schroeder** · 13-Jul-2006, 09:16

I recently purchased a Metrolux II timer, and am trying to calibrate it with my Zone VI cold light. The unit calibrates properly with my older cold light head with a 20 year old blue sensitive bulb. On my newer cold light head, with a new aristo V54 hi intensity bulb installed, the light seems too bright to calibrate. (It will calibrate with one thickness of white paper towel as added density.) I have a spare Kodak .2 density gel filter. I am wondering if the cold light gets too hot to safely use the gel below the sensor. Has anyone had this problem? If so, how did you remedy it?
Thanks,
Ken
ps...the new bulb stabilizes like gang busters with my Zone VI stabilizer. It gives full range, although I have not actually printed with it yet.

**robc** · 13-Jul-2006, 13:37

cold light too hot?

if your filter is a true gelatin filter then it may well melt. If its position is above the negative, then lighting filters will do fine. Lee make ND lighting filters which are suitable for hot lights. A big sheet of ND .1 costs very little and can be cut to size. Use several layers to get brightness to where you want it. But if what you wanted was brighter, then why do you want to dim it, unless its only for calibration purposes.

**David A. Goldfarb** · 13-Jul-2006, 15:05

I was able to calibrate my Metrolux I with the Aristo high-intensity head for my Omega, which I think uses the same bulb, and it works perfectly. I recently knocked out about 100 postcards with very short exposures and didn't get any exposure drift at all.

If I remember correctly, I think I may have done it with the sensor facing away from the bulb, and I recall there being instructions to that effect. I'm away from home, otherwise I'd check the manual. If you e-mail Metered Light, they can give you some advice, but it may take a while for them to get back to you.

**Eric Woodbury** · 13-Jul-2006, 19:55

Ken,

I'm using a V54 12x12 and MetroLux II. My cal number is 180 with the sensor mounted in the top looking down. I just peaked inside and it isn't looking directly at a tube, but almost between two windings and at the plexiglass. I also ran another little experiment to see what the cal number would be with a sensor looking right at the tube (I have a spare sensor). It would be about 50% brighter. I don't remember the allowable range, but turning the sensor away from the tube is fine as David mentioned. ND would work, too, and I don't think it would fade, but for melting it would depend on the material.

No point in taking chances, just point the sensor away from the tube and look at the wall of the housing. Important thing is that the sensor not move, that it always sees the same percentage of the lamp output, and that it not face the tube directly near the ends of the tube. (The ends of the tube change temperature so much that their light output varies differently than the rest of the tube.)

If you still get too much light, then you could epoxy a piece of aluminum foil or thin metal directly to the surface of the sensor and poke a small hole in it. Aluminum foil doesn't fade and this would be like a little f/stop in front of the sensor. Or, get a cheap glass ND, break off a chunk, and glue that over the sensor.

If it is still a problem, let me know and I'll give you some other ideas.

-EW-

**Ken Schroeder** · 14-Jul-2006, 02:07

Thanks for the replies. Eric, the (Zone VI) sensor is now looking directly at a tube. This is no fault of Zone VI, since the unit was designed for another bulb. The position probably also explains why it stabilizes at such a bright level with my Zone VI stabilizer. My unit came with another sensor. I think the best long-term solution would be to install it facing away from the grid.
I bought the high intensity bulb to work with variable contrast paper. The "high intensity " means there are seven rows in the grid instead of five. The original bulb worked quite well with graded papers, but was very slow with variable contrast papers (with the added 40cc yellow filter above the diffuser. In the back of my mind, I am also hoping the extra tubing of the new lamp may help lighten some of the dark corners when printing 4x5. (That may not be realistic; the real solution is a 5x7 lamp.)
I originally bought the new lamp to work with the Zone VI stabilizer I have used for twenty years. The Zone VI stabilizer always gave very consistent results. I thought this might be a good time to try the Metrolux unit. Each unit has some features I like very much. I like the simplicity of the Zone VI unit, and especially like the dimmer feature. I often print small and like long printing times for control. I believe the Metrolux will be more versatile once I become fluent with it. I like the built in metronome and printing meter. It is not as "plug and play" as the Zone VI, but the learning curve seems worth the effort for the versatility.
The sensor trouble is just a short-term bump in the road. Thanks again for your replies.

**Eric Woodbury** · 14-Jul-2006, 07:56

If I remember correctly, the Z6 sensor is larger and therefore produces a larger signal, thus the problem. Good luck. It will work fine.

**Ken Schroeder** · 23-Jul-2006, 13:09

just a follow up: I tried swinging the bulb 180 degrees. It is not quite symmetrical, and swinging it and filing out the round holes made it possible to clear the grid away from the direct path of the sensor. This brought the intensity down from "1" (too high) to something in the high nine hundreds, still too high, but close. I then mounted the spare sensor I had. By following the directions in the manual and pointing it upward at an angle from the grid, I was able to calibrate my coldlight at 295, well within the range of 10 to 900. Mounting the sensor was not such a difficult project. Thanks for the help.

**Richard Schlesinger** · 24-Jul-2006, 11:34

I have a rheostat Aristo sells for use with their lights. A very handy arrangement I have found. It allows me to always print with my lens stopped down 2 stops with usable times. Also good for calibration purposes as it has a scale so when set below 100% one can get repeatable intnsities etc.

**Ken Schroeder** · 24-Jul-2006, 19:38

Richard, do you use the Aristo dimmer with a stabilizer? I have found the rheostat feature of the Zone VI stabilizer very useful. It lets me keep my printing times in a comfortable range for me. I haven't tried the Metrolux unit yet. However, I will certainly keep the Aristo dimmer in the back of my mind if I should want the extra control of a dimmer. I presume I would have to recalibrate the Metrolux to the different rheostat levels? (Very quick to do, and no hassle)

**Ken Schroeder** · 4-Sep-2006, 05:11

Follow up after printing with the Metrolux: The unit works very well. I especially like the metronome feature. With my preference for small prints and long exposure times, I do miss the dimmer function of my Zone VI compensating timer. I plan to add an Aristo dimmer. my one grumble with the Zone VI unit is the rheostat, while consistent, is not easy to accurately place. It needs a more precise scale instead of the the rough lettring system. I have found the Zone VI compensator invaluable over the years. The Metrolux seems like a well designed and manufactured tool as well.