Zone VI variable contrast head test

[MVNelson]

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.

 

[Loose Gravel]

I think you are on the right track. Test with Max Blue and Max Green. This gives the high contrast and the low contrast. I would also want to know how bright the lamp is, i.e. how long is a typical exposure. You could print a step wedge and enlarge it 2x as a standard. The final question would be what is the max contrast that the paper, your sample, can deliver. For this you will need a 'bluer' light source or a white source and some very strong blue filters (#47). I don't think the low contrast minimums are necessary as they are always softer than anybody would ever use.

A more extensive test would include the light intensity dirft of the two tubes under different conditions, but this is difficult without more instrumentation than you may have.

 

[MVNelson]

after a little trial and error the best brigthness setting seems to be @ 8. This a fairly low intensity light source and took 18 secs @f/8 to expose the 4X5 in step tablet at about 1:1 projection. The step densities ranged from .04 to 2.0. on the average. What I am most interested in is findind out exactly what setting give s me say nominal grade 2 and the ability to move logically with out trial and error to say grade 3 or grade 1.5 etc. The way things sre this moment is that I would virtually have to test each setting available A-H(8 steps) hard and soft equals 64 test strips for each variable contrast paper I want to use. If I could just get to where the head is smoothly trendiing step wise to soft and hard hat would very useful. The BTZS plotter test so far shows that leaving the hard or soft dial fixed and moving the other dial in a stepwise fashion does not net a contrast step tablet test contrast value where one might logically expect and sometimes the contrast value moved in the opposite direction expeced. e.g. H/E,H/C,H/A,MAX-GREEN is the expected order moving towards lower contrast. However y 1st test showed the order H/C,H/E,H/A,MAX-GREEN. Further more I can't figure out what setting would get a contrast value between H/A(ES 1.22) and Max-Green(ES 1.95). The 1st letter is the soft dial setting and the second letter is the hard dial setting. H would represent the most intense green and A-H would be in ascending order increasing intensity of blue. Soooo..H/A(paper grade 1.3)and no logical way to get anything in between MAX_Green(paper grade way below 0). I suppose I could go to split exposure printing using the max green and max blue exposures but I never worked like that and it seems contr intuitive to me when I have an enlarging head that is supposed to be able to simply dial in the single exposure contrast filtration value.

 

[Allen Friday]

I did a BTZS test using the Zone VI head and Kodak Polymax fine art paper a couple of years ago. I recently repeated the test last week using Ilford Warm tone FB. I have not read the strips for the Ilford test yet, they are at my office and I haven't had time to finish them. But, here is what I did.

I projected the test strip onto sheets, and made 11 different combinations. I always leave the light level, middle knob to max. I only adjust the soft and hard.

Start with both the hard and soft set to max. Then turn one knob down a quarter turn at a time, ending with the knob set off and the other at max. Then set them both to max and turn the other down quarter turns. Finish with max/off and off/max for soft and hard.

This gives 11 combinations. Test using the densitometer and plot--it will give you the grades for those setting on that paper.

I found that on the Kodak paper, the two knobs set to max gave a grade two print. Grade one was soft=max, hard verticle. Grade 0 was soft=max and hard=min. Grade 3=soft verticle and hard max. Grade 4=soft min, hard max.

I don't think you need to test every possible comination on the dials. I found using quarter turns gives enough info to get the basic grade changes down. From there you can fine tune as much as you want.

 

[Allen Friday]

One more thought. Do you have the Compensating Enlarging Timer for the head? If not, you will probably get inconsistent results if you do not let the head heat up fully. The timer adjusts the exposure automatically to compensate for the output of the two lights. Without the timer, you will have to let the head heat up each time before making the exposure on the paper.

 

[MVNelson]

I like what I am reading here ! Do you have the Zone VI 4X5 model with the 3 dials with letters on the hard and soft dials? Also, is yor unit fairly low intensity (25 to 30 secs exposure f/8 for "typical" 8x10). I will try your test set up tomorrow pm. Thanks a lot. My initial results gave me a near grade 5 with max blue with green off and grade less than 0 grade max green with blue off. However all six in between values I only got low grade 3 to grade 1. I can't wait to try your settings. Thanks Allen.

 

[MVNelson]

I don't have the compensating timer.Maybe I need one. Supposedly that technology was built in head. There is a green light that will come on when the head is ready for exposure and if it is off a "blank" exposure is supposed to be made which preps the head for proper expsoure.

 

[resummerfield]

I had the same Zone VI VC head and did the same BTZS testing as Allen Friday, but I did 21 combinations. This was overkill, and 11 combinations or less would have given the same results, which were much like Allen’s. I then plotted my results on a graph to get the intermediate values, and then made a chart like those on pg.76 of “Way Beyond Monochrome” by Lambrecht and Woodhouse so I would know the exposure time adjustment needed when I changed grades.

According to Calumet, the Zone VI head has built-in stabilization and thus does not need the compensating timer. However, I’ve always used one—the RH Designs vario model—and would highly recommend one because, with my head, the green light did not always stay illuminated when the light intensity dial was turned up beyond about 6.

 

[MVNelson]

thanks also. great advice. i can't wait to get to the test

 

[Allen Friday]

Hi MVNelson,

I bought my enlarger five years ago. As far as I know, it is the latest model made. It has the three knobs of which you write.

My basic settings for each knob are off, min, half way between b-c, half way between d-e (straight up), half way between f-g and max. These settings are basically quarter turns of the knobs. I put small peices of glow-in-the-dark tape at each setting so I can dial it in quickly even under a very low safelight.

I start with both knobs set to max and then adjust as needed. For more contrast, I turn down the soft knob. For less contrast, I turn down the hard knob. I adjust the knobs using quarter turns, and then fine tune the contrast between the quarter turn settings when needed. I always have one of the dials set to maximum and change the other, instead of trying to adjust them both.

When I first started using the head, I had a hard time getting consistent results. I would make two identical exposures, and one would be darker than the other. The problem went away one I got the compensating timer. I know the head is not supposed to need it. But, I find the timer a necessity.

 

[Nicholas Lindan]

An alternative is to use the head for split-filter exposures: one exposure at max green and one exposure at max blue. The intensity control scheme in this head is a bit 'iffy' and cold lights don't like to be dimmed even in the best of circumstances.

 

[resummerfield]

.....I suppose I could go to split exposure printing using the max green and max blue exposures but I never worked like that and it seems contr intuitive to me when I have an enlarging head that is supposed to be able to simply dial in the single exposure contrast filtration value.

After all my testing of my Zone VI VC head using one exposure, I started testing using the split filtering method. Initially I found the split filtering method difficult, but within a short time I became comfortable with it. Now, I almost always use the split filtering method.

 

[BruceN]

You definitely need a compensating timer. I use a Metrolux II and really like it. It doesn't do f-stops, though. Here is the chart I use for contrast adjustments. http://www.bnimages.com/files/zonevicontrast.pdf I forget where I found it. Hope it will serve as a good starting point for you.

Bruce

 

[photographs42]

Hi guys. I’m new here so I hope I’m not butting in. I use the 5x7 version of the Zone VI but it sounds like it is just like the 4x5 but bigger. I’ve used it for several years and find it very consistent w/o a compensating timer. I don’t remember his name, but when I bought it the “expert” at Calumet assured me that compensation was built into the head and I wouldn’t need a special timer (he actually talked me out of buying it).

As for grades, I did considerable testing when I first bought it and from my tests (using a step wedge, I don’t have a densitometer) I decided that if I set the blue to Max and varied the green, I could get whatever I need. I seldom need lower grade than about a grade 2 although I must admit that I seldom think in terms of grades, just more or less contrast. The brightness control is always on 10 and I wish I could crank it higher most of the time because I do some large prints. BTW I use Ilford MGFB paper.

Bruce, thanks for the chart. I have never seen this and it looks interesting.

Jerome

 

[Allen Friday]

Bruce,

Thank you for posting the link to the chart. I looked for this several times and never could find it. I now have it book marked.

I also agree with Jerome in that when using the head, I rarely think in terms of grade, only more or less contrast. (I do test for different grades, however, more out of curiousity than need.) About the only real need I have for defining the exact grade of a print is when I start. I would like to print on grade two, so I have to establish which settings are a grade two on each paper. I can then vary exposure and development of the film to match that setting. Basically, I use 1.05 as my goal, regardless of the silver enlarging paper brand. If I miss on the development, which happens regularly, I just adjust up or down as needed.

To me, the main advantage of the head is that it prints between grades by just turning the knob, and you don't have to fiddle with physically changing filters.

As to the timer, I need it because of the way I print. Even when split grade printing, I find it valuable. If I set the hard setting to 8 seconds, for example, I can hear the timer speeding up as the light source warms up. I get consistent exposures with it. I didn't before I had it. But, I would recommend that any printer try printing with out it first. If you get good results with out it, no reason to spend the extra money.

 

[BruceN]

Hi Jerome, you're welcome to butt in, and welcome to APUG! Actually, I don't think the Type II Zone VI VC enlargers came in a 4x5, it's just that the 5x7 works just fine with a 4x5 neg carrier. I also keep the brightness cranked all the way up, for the same reason. There is a stabilizer built into the head, but I think it is inadequate. Before I got the metrolux I had some inconsistencies. They were apparently due to voltage fluctuations caused by the furnace kicking on and off, etc., and temperature variations in the tubes. I also know other (much better) printers who have experienced the same thing with this enlarger setup. The Metrolux II timer solved this beautifully, and added some other nifty capabilities as well. There is a cord available for them that allows them to plug directly into the sensor already installed in the Zone VI heads. Like you, I don't really think in 'grades' with that enlarger anymore - just 'more' or 'less'. I just use the chart as a general guide to see where I end up.
I haven't experimented with split-grade printing, yet, but I plan to.

 

[BruceN]

Bruce,

Thank you for posting the link to the chart. I looked for this several times and never could find it. I now have it book marked.

Hi Allen, you're quite welcome. You'd better download it, though - I just threw it on the site for this thread, so there's no telling how long I'll leave it there.

Bruce

 

[Allen Friday]

Bruce,

Hard copy in hand. Thanks again.

Allen

 

[MVNelson]

I am wondering if anyone else with the 4x5 head thinks that thishead puts out a fairly low level of light? I am appreciative of all the comments and suggestion. My main purpose for testing paper contrast level was to get the best aim point for my 4x5 negs much like Allen and I also use a paper es of 1.05 as my aim point in the BTZS approach. For pyrocat-mc I am up to 1.20 for vc paper. I also agree that I think/work in terms of higher lower contrast as oppose to grades or es once I get started with the actually printing process. I am truly(truely?) grateful for the great responces to this my first posting in APUG. I am off to try the suggestion. I am looking into the compensating timer if my test results prove to be erratic. The step tablet/densitometer process check will easy show if this is a problem. Again Thanks you all!!!!
Miles

 

[BruceN]

You are right about that, it's certainly not the brightest head out there. Look at the silver lining though - if you're doing lots of burning and dodging you'll surely get your arms in shape with the long exposures.

Bruce

 

[MVNelson]

the projected step tablet exposures are hanging to dry! They seem to have good overall range visually. When dry in a.m. I will read them and we'll see....I did notice that at 1st I had to do a few "test exposures" to get the green light (ready light) to stay on consistently . Once the system got warmed up everything seemed to go smoothly ready light constantly on.

 

[lee]

turn on the machine and hit the focus button while setting up the chem trays. That will get you into regulation quickly. If the light goes out during the session just hit the exposure button and it will take you back to regulation.

lee\c

 

[MVNelson]

Well the results are in and I have discovered that my unit does not function as advertised or I did something awfully wrong! My step tab study was done very carefully. I used fresh chem LPD 1:4, Forte VC FB, all exposures were @ f/8 18 secs, all the step tabs read with X-rite densitomer. The soft=max,hard=off showed a paper grade 0(1.57), the soft=off,hard=max showed a paper grade 3(0.82) but all the other combinations showed a range between 0.9 and 0.8 (essentially all grade 3) !!!! I repeated the study with Oriental VCFB and again with Forte VCFB and the pattern is the same only the all green exposure is different, grade 0 or less and all other combinations a very close in contrast. It is though any Blue tube input at all and the contrast gets fixed in the same paper grade for oriental it was grade 1. Looking a the printed step tablets they are very similar in contrast as read by densitometer, only the green on blue off step in each study is obviously different. I bought this unit new about five years ago. It seemed to function inconsistently then. I sent it back to the Calumet repair. They sent it back weeks later. Meanwhile I went back to using my Beseler/Minolta 45A head with its extreme level of accuracy and repeatability which I needed for dye transfer separations and matrix exposures. Using for printing black and white was noncoventional because of the strobe light exposures. It did hae the advantage of being able to very quickly produce an 8 step contrast "ring around" that was exceptionally accurate. I bought the Zone VI head to be able to do more conventional printing after I learned the BTZS technique. When my unit came back I noticed it had lost at least an f stop of brightness. I called the service people at Calumet and was encouraged to give the unit a honest chance. Now that I can test the unit with good quality B&w negatives and step tablet/densitometer studies I have finally come to the conclusion that my unit just does not work properly. Now I have to decide if I am wlling to pay another $200+ to send it back to Calumet for another shot at fixing it!!!!! Meanwhile the 45A head goes back on for now. I thought about ordering the compensating timer to see if that would help but I am getting warey of the old adage of throwing good money after bad.... Any suggestions would be quite welcome..

Miles (of frustration)

 

[MurrayMinchin]

Miles (of frustration)

That sounds familiar...

I used to print with a Zone VI cold light head on graded papers. My negatives were developed to (or at least attempt to ) print on Ilford Galerie FB, grade 2, developed in Zone VI developer. When I got the Zone VI VC cold light head I was shocked by the heinous contrast I was getting with the head at 'normal' contrast settings.

What worked was putting a 40Y filter above the negative. This made exposures longer, but prints made on Ilford Multigrade FB with the VC head's Soft and Hard lights both set at 'E', developed in Ansco 120, were pretty close to prints made with the old cold light on Galerie grade 2.

I didn't want to change the way I developed my negatives because I had been doing them the same way for a couple decades. The light source had to compromise...not my negatives!

All the googling I've done on this light source has shown me how extreme they can be, contrast wise, from one head to the next. I'm researching light sources to find its replacement after the new year...

Murray

 

[resummerfield]

Did you remove the lens and look at the light which changing the dial positions? With the SOFT on MAX and HARD set to OFF, the light should be very green. With the HARD set to MAX and the SOFT set to OFF, it should be very blue. Now, with the HARD set to MAX, slowly turn the SOFT on and increase the dial to the MAX position. Does the light change gradually to a blue/green mix?

From my old notes, MGIV Fiber developed in Dektol 1:2 for 2 min. and toned lightly in Selenium 1:20 for 4 min., I had a Grade 2 (1.05) with my HARD light was set to MAX and the SOFT set to G. With the HARD light only I had almost a Grade 5 (0.54) and SOFT only gave a Grade 00 (1.84).

From your description, it almost sounds as if one rheostat has some dead areas, in which case I would send it back to Calumet.