Zone VI 4X5 variable contrast head calibration

Discussion in 'Darkroom Equipment' started by MVNelson, Dec 4, 2006.

  1. MVNelson

    MVNelson Subscriber

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    This is my first post. I have a zone VI variable contrast head, which I never felt did what it was suppose to do properly. I decided to do a series of BTZS paper test to determine once and for all if it was worth struggling with. The problem is that the there are three dials. One is for "soft"(green) and marked A-H,max,off. One is bightness marked 1-10. One is "hard"(blue) and marked A-H,max, off. There are too many possible settings (without exhausting a lot of time and materials)to test paper exposed at each possibility. I did a prelim.. at max blue/off green and max green/off blue on Ilford Multigrade IV-RC. The plotter program reads ES 0.70(paper grade 4.7) for max blue and ES 1.95(paper grade < 0) max green. The big problem comes with trying to choose which are the logical combinations of settings of the hard and soft letters that would yield useful data. I am a bit baffled because I tried "c" on soft with "h" on hard and got ES 0.90(paper grade 3.2) while I got ES 0.98(paper grade 2.8) with "a" on soft and "h" on hard. The "a" soft should provide less green light than the "c" soft and therefore should have in combination with "h" hard setting produced the more contrastly step tablet test. I believe that this why I have never been able to get consistent use out of this head because turning the dials intuitively up and down to get more or less contrast was not producing the desired color mix to produce the anticipated paper contrast. If anyone has any suggestion on how to set up a useful test scheme for the zone VI variable contrast head they would be greatly appreciated. This is the 4X5 head on Beseler MX chasis.
     
  2. MurrayMinchin

    MurrayMinchin Membership Council Council

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    Hi there - welcome aboard APUG :smile:

    First off, do you have the Zone VI VC head that has the green LED on the front of the head which turns on to indicate when the light is stabilized? Some older ones don't have that feature...this might explain your erratic results as for one test the light may have been warmed up, and cold for the other. My heads LED won't come on with the soft light set on 'H' or 'Max' (indicating it is incapable of producing that much light) and it takes forever to warm up enough to stabilize even at 'F'.

    Another question; are you using a Zone VI Tik-Tok compensating enlarging metronome? I switched to a small electronic musicians metronome when I finally realized the Tik-Tok was only reading the total volume of light, not the colour of the light. This meant that if I had nailed a delicate high value texture for example, and changed the Hard light to change the low print values, the Tik-Tok would change the amount of time between the beeps...which meant that even the amount of Soft light hitting the paper had now changed.

    Good luck with your head scratching!

    Murray
     
  3. MVNelson

    MVNelson Subscriber

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    I have the unit with the green light on the head and the 3 dials on the black box. I have actually gotten some good replys on the "enlarging section". I can keep the green light on @ all the settings. Every so often if I change some thing widely I will have to do a blank exposure then the green light returns. thanks
     
  4. MurrayMinchin

    MurrayMinchin Membership Council Council

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    Braggard! (Me-thinks mines a bit of a lemon :sad: but it's not an uncommon problem with these heads).

    Murray
     
  5. MVNelson

    MVNelson Subscriber

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    Hey Murray I really believe most of these heads were lemons. They seem to vary widely in performance and stability. They are an example of great concept but poorly executed engineering. I have never experienced an enlarging head of such looooooow light intensity. Mine might be ok for 8X10's at 20 sec exposures but I can't imagine what 16X20 exposure might be!!!
     
  6. MVNelson

    MVNelson Subscriber

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    Just to close this thread after exhaustive test my head was dysfunctional is on its way to Calumet for another shot @repair.

    Miles
     
  7. michael9793

    michael9793 Member

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    come on guys, If you are doing Les Mcleans way of printing you don't worry about all the dials and the settings. you leave the dials on max and work with the timer. 2nd if you are using a stop clock timer or a Zone VI enlarging timer with the sensor your times will be the same no matter how the cold the tubs are. 3rd I print 20x24's from 4x5 negatives on mine and I'm not sitting there with printing times of 45 sec to a min. and I get great quality out of my prints. I have a 4x5 head and I have a 8x10 head, It takes min 5 mins to switch them out so the two heads make it cheaper than two enlargers.
     
  8. MVNelson

    MVNelson Subscriber

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    If I tried to print a 20X24 print with my 4X5 head The exposure with both tubes at max would be in the order of 2+ mins!!! Talk about reciprocity and boredome issues! My negs are quite standard in exposure.dev using the BTZS and not all "beefy" either. Its not about technigue it is about
    a dysfunctional enlarger headthat is on its way back!

    Miles
     
  9. michael9793

    michael9793 Member

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    Miles then I would say you do have a problem, compared to mine that is a problem. I wonder if some type of voltage regulator is bad. I can't believe that both the green and blue tubes are bad. I'm running on a stop clock timer, but I would say a standard print is about 35-40 sec each color and stopping down to around f/11-f/22, depending on the density of the negative. this gives me latitude for dodging and burning.

    Mike
     
  10. michael9793

    michael9793 Member

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    I'm talking 16x20 now. 20x24 is usually f/5.6 to f/11 and maybe a few seconds longer or shorter
     
  11. MVNelson

    MVNelson Subscriber

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    your unit is working about how my unit worked when i first purchased it after the first repair my unit was returned to me with loss of about 60% of its intensity and the current problem of not being able to change the blue light settings. We'll see how it gets back to me in a few weeks.....