aristo vcl 4500
the question i have is do you need to use a compensating time with the vcl 4500 or is it stable enough to use w/o. i have read that installing a probe will only read one of the bulbs , i also understand that both tubes can differ in output so does it make sense to install a probe?
thanks for the help
Last May I emailed a similar question to Louise Kessler in the Specialty Products Group at Aristo Lighting Technologies, Inc. Here is her reply (in boldface) as she interleaved it into my original message:
Originally Posted by wager123
I have been kicking around the idea of upgrading my old Zone VI (OEMed by you?)
false- this was started by Zone VI's original owner- Fred Picker
cold light head (w/V54 lamp) to a two-lamp, variable-contrast unit. My nagging question is this: My current unit is controlled by the closed-loop Zone VI Enlarging Timer. While I presume the small light intensity sensor
fiber optic sensor
inside the lamp housing has a color bias,
in a single lamp design this should make no difference.
There is a difference but you would correct for this while you are doing your test prints.
But what about in a dual-lamp environment, where the light color is - by design - variable?
Both the single and dual lamp systems are considered variable contrast systems. (The single lamp system just has both the same phosphors in the one lamp.) The use of the fiber optic sensor is a Fred Picker design. We don't advocate it, but photographers that make very large prints do like using the sensor in commercial applications for a quicker reads of the light intensity.. It's a personal choice whether you want to rely on a sensor or your own skills that you've worked so hard to develop.
In my current setup, that timer does a wonderful job of holding my net exposure times rock solid and repeatable. Can such a timer be similarly expect to do the same in a two-lamp environment?
Most enlarger systems will be repeatable, but I've never seen anything be "rock solid". Over time the lamps age, chemicals/materials/environment changes -too many variables. There is fluctuation. As for the timer, my engineers feel that a timer is a timer is a timer. If you are comfortable with the timer then continue to use it.
Thanks for any light you can shed (ouch! ) on this issue,
seem a little curt on her part.
is anyone useing the vcl w/o a fiber optic sensor.
i would like to hear their experences .
I have been using the Aristo 4500 VCL for 19 years since they were first introduced. I am on my second one. I do a lot of custom printing as well as personal printing, meaning I spend seemingly my whole life in the dark in front of my enlarger. I merely have the head plugged into the wall and into the back of a Beseler audible repeating timer. I am on my 4th timer and need a new one.
I have many times needed to make batches of prints and found it is like using the regular Arista cold light head in that once you get into the batch several prints, they start coming out about 10% too dark so you have to adjust. But after that you can keep printing the same thing over and over till the cows come in and it is very consistent.
When I am just printing normal (not batches), my habitual technique is to always hit the focus button for maybe 3 seconds just before putting the new paper in the easel and making the print. If I take sort of an extended break from printing.. like an hour.. I will hit the focus button for maybe 30 seconds before I start printing again.
The tubes in the head last a very long time. When they finally started getting old in my first head I didn't notice anything except that I would make tests and then a print and the print was slightly off from what I expected ... causing long days and anger and much cursing. Then I got the new head and low and behold I became a good printer again. I would have just gotten new tubes for my first head except that the heads had evolved in the meantime and the tubes were different.
If my Aristo 4500 VCL went on the blink, I would just find a way to get another.