[pure-silver] Re: ZONE VI VC HEAD, was No More Below the Lens Polymax Filter Kits?

  • From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Sun, 08 Feb 2009 18:12:18 -0500

mail1 wrote:

I have not had an opportunity to use the Zone VI 4x5 model.

With my Zone VI type 1 head maximum green and maximum blue settings produces
an ES.78 effective grade 4 shot toe curve.  With the Maximum blue lamp on
and green off the head produces ES 0.60, eff. grade 5 short toe. So it
appears the tubes might be different in the 4x5 head.


OK. With mine, I get 12 steps from pure white to maximum black on my step
tablet (0.15 density per step) for what I call grade 00. 1.8 density range.
This is with the green at maximum, and the blue turned off.

With both blue and green at maximum, I get what I call grade 2, with 9 steps
density range. 1.35 density range.

At the other extreme, I get 7 honest steps (or 6 wishful thinking steps) for
what I call grade 5. 1.05 density range. I get 7 honest steps for what I
call grade 4. This is with the blue at maximum and the green turned off. I
have not tried putting a #47B filter in there to get more contrast. I might
if I were desperate, but a piece about 6' in diameter costs a lot these days.

In my experience, the toe of Ilford MGIV does not change much with the
filters; but the shoulder changes a lot. This is testing my step wedge. It
may be that subjectively there are subtle differences in the toe that a 0.15
wedge step size hides. These tests were all run on a new box of MGIV paper
purchased from B&H, all run in about 2 days with fresh chemicals each day.

I do not remember how to convert density range to Exposure Scale (which is
what I suppose you mean by ES). I thought they were identical, but your
results are so different from mine that i doubt they are experimental error,
so I hope we are talking about different things.


A thought about the apparent dimness of cold light heads.


I was not saying cold lights were dim, just my Zone VI. I have a one-tube
Aristo D-II HI head that is plenty fast enough.


My type 1 cold light have a lamp power supply / controller box which
measures 12x11x6 inches inside this box are two large transformers with
Variac controllers. This unit appears brighter than my Aristo VCL4500. This
is because the difference in tubes between the two light sources. The Zone
VI has phosphor coated tube with a wider spectrum of light than the VCL4500
which uses phosphor coated colored glass tubes so the spectrum is narrower.
Since the eyes response to blue tube is very low the VCL4500 appears darker.


My Zone VI head has a green and a blue tube. Each has some phosphor inside
each tube.

My control box for my Zone VI unit is very small. It contains three
potentiometers, one of which I find useless. If you turn it to max, that is
the brightest the unit will go, so I always leave it at max.
Then there are two, one for green and one for blue.

There is a switch that has two positions. One is Print, one is Focus. In the
Focus position, it turns on both tubes at maximum brightness. I never tried
printing with it in the Focus position.

Those knobs are definitely 1/2 watt cheap potentiometers; I am surprised
they are not the 2-watt Ohmite (probably Allen Bradley) ones which have much
less noise and much longer lasting.


I checked one of my print logs and noticed an 11-14 enlargement of a 6x6
dense negative, requiring a paper ES 1.2 was printed on Ilford MC Paper with
my Zone VI set at Max Green - Min-1 Blue which equaled eff. Grade 1. The
time of exposure was 12 sec. at f5.6 using a 90m/m Schneider APO lens. The
same negative printed on my Durst condenser enlarger 300 watt bulb at 110
VAC using an Ilford 0 filter; eff. grade 0. The time of exposure was 20 sec.
f 5.6 105m/m Rodagon Apo lens. If we allow for the difference in lamp
heights because off lenses and the papers response to the different light
sources the exposures are similar. The image on the easel from the condenser
is quite bright compared to the Zone VI. The VCL4500 is dimmer still, and an
addition 1 stop grade 5 burn to the sky would have been difficult for me
because my eyes seem to have a poor response to the VCL 4500 blue lamp.

For large print on my Durst I use a 500 watt lamp run at 120 volts which
leaves the cold lights in the twilight zone.

I have noticed the different response photo paper has to each of the light
sources imparts a different rendition of the same negative. Cool.
Jonathan Ayers [mail1@xxxxxxxxxxxxxxxxx] 
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Jean-David Beyer
Sent: Sunday, February 08, 2009 4:42 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: ZONE VI VC HEAD, was No More Below the Lens
Polymax Filter Kits?

With my Zone VI VC head (a 4x5 model), I can adjust the green and blue tubes
separately.


Some VCL4500 units have a rheostat to adjust the green light level to

reach

the higher contrasts. The Zone VI also includes variable green and blue
light. The problem is how to decrease the green light as the blue light is
increased so that the light intensity stays the same so that the exposure
does not have to be adjusted with each contrast adjustment.
Since the Zone VI VC head is so dim, what I do is run either the green or the blue tube at maximum intensity so as to get as much light out of the unit as possible. 

So for grades 00, 0, 1, and 2, I have the green at maximum.
For grades 2, 3, 4, and (wishful thinking) 5, I have the blue light at maximum. I calibrated things with a step tablet and a photometer so that Zone V always matches the grey card, using a constant 22 second exposure time. This results in apertures of f/8 for the extreme contrasts up to f/11 for grade 2. Fortunately, my enlarging lenses can have their click-stops turned off. So part of my chart looks like this: 

GRADE   SOFT    HARD    F/
00      MAX     OFF     8
0       MAX     B-      10
1       MAX     F       10
2       MAX     MAX     11
3       E       MAX     10
4       MIN     MAX     9
5       OFF     MAX     8

This is for Ilford MGIV VC paper in my version of D-72 developer 1+2 using a
Kodak T-14 step wedge in my enlarger's negative holder for an 11x14
enlargement.


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