Printing black and white with a color head

[fschifano]

I'm using the same color head hat the OP is getting with his D5, and it works great for variable contrast papers. But it didn't always work so well. It's not the filters that fade though. The light mixing box in the head is lined with white styrofoam, and over time this material will yellow. Well, that certainly can screw things up a bit. Fortunately, it's very easy to replace the foam. When I did that, I immediately gained a grade higher contrast for a given filter or setting. Prior to relining the mixing box, printing without any filter delivered a decidedly soft print from a normal contrast negative. Once I fixed it, everything was exactly where it was supposed to be. No joke. KHB Photographix has these kits for sale on Ebay and they're not very expensive.

 

[Lee L]

The Beseler Dichro 23dga color head goes to 160 on all channels. (Way better than going to 11.)

The OP hasn't actually specified a Dichro head yet, although that's likely to be what he'd get with a D5. As ic-racer has noted, the earlier Chromega head had variable density color wheels, not dichro filters.

Good info on the yellowing styrofoam Frank. Harry Taylor (classic enlargers) is of the opinion that any white styrofoam should work, although he doesn't say he's tried it. He also recommends just turning the yellowed interior face of the existing styrofoam to the outside, which puts the fresh white outer face of the styrofoam toward the box interior.

My lens turret works with 50mm lenses and the proper oval lens board on a D5-XL. The instructions imply that it will work just fine.

Lee

 

[24x30]

To know which setting to use at a color head it's helpful to make once a set of test stripes with a grey scale (for example with one from stouffer). There are papers which will never reach more than a #4 (classic art pw, adox pw, foma pw). There are papers which vary from batch to batch (eastern european papers). Older paper is getting 'weaker'.

Teststripes also will help to understand what you can get from the equipment you're using. Given scales will never by very precise.

Making stripes from yellow (for #00 ...) up to magenta (for ... #5) will give you a table what you can get with which setting. A description of how to, is given in the book of an Apug member 'Beyond Monochrome'. From this table of measurement settings you can go to filter numbers, but you will not need them anymore.

This is a table of equivalents I got with my light meter (Kunze):

Gradation logD min - logD max
00 1,70 - 1,90
0,0 1,50 - 1,69
0,5 1,35 - 1,49
1,0 1,25 - 1,34
1,5 1,15 - 1,24
2,0 1,05 - 1,14
2,5 0,95 - 1,04
3,0 0,83 - 0,94
3,5 0,68 - 0,82
4,0 0,55 - 0,67
4,5 0,45 - 0,54
5,0 0,35 - 0,44​

rudi

 

[Casey Kidwell]

Thanks Fred. My, what a big camera you have. 24x30 and fschifano, that is some great info. It's unbelievable what a great resource APUG members are.

 

[coops]

I have an Omrga enlarger with a dichroic color head, and a set of Ilford filters. I have read that using Ilford VC paper with no filter is equivalent to grade two, but I get quite a different print than if I use a grade two Ilford filter. Which one is correct?

 

[fschifano]

OK. Here's the deal. When Ilford says that you'll get an equivalent of grade 2 without a filter, they do so with the assumption that a standard tungsten lamp is used. They also say that the result is approximately grade 2. The color temperature of a standard tungsten enlarging lamp is about 3000K. The color temperature of the tungsten halogen lamps used in color heads is considerably higher (shifted more towards the blue end of the spectrum) at around 3250 to 3400K. Knowing that variable contrast papers deliver higher contrast when exposed to blue light, this should not come as a surprise.

 

[ic-racer]

I'm using the same color head hat the OP is getting with his D5, and it works great for variable contrast papers. But it didn't always work so well. It's not the filters that fade though. The light mixing box in the head is lined with white styrofoam, and over time this material will yellow. Well, that certainly can screw things up a bit. Fortunately, it's very easy to replace the foam. When I did that, I immediately gained a grade higher contrast for a given filter or setting. Prior to relining the mixing box, printing without any filter delivered a decidedly soft print from a normal contrast negative. Once I fixed it, everything was exactly where it was supposed to be. No joke. KHB Photographix has these kits for sale on Ebay and they're not very expensive.

Good post.

 

[ic-racer]

I have an Omrga enlarger with a dichroic color head, and a set of Ilford filters. I have read that using Ilford VC paper with no filter is equivalent to grade two, but I get quite a different print than if I use a grade two Ilford filter. Which one is correct?

You can answer stuff like this if you can get your hands on a 21 step wedge. Contact it against the situations in question. The one that gives you about 7 grays is grade 2. (but it really doesn't matter, as others have pointed out)

 

[Smudger]

IC-Racer :the head was the original dga head,and I seem to remember using the Kodak figures. The mental impairment came from the need to retest for exposure with even slight changes in grades. The Ilford filters don't require compensation until grade four. Life is good again.

 

[fschifano]

You can answer stuff like this if you can get your hands on a 21 step wedge. Contact it against the situations in question. The one that gives you about 7 grays is grade 2. (but it really doesn't matter, as others have pointed out)

You might prefer the 31 step wedge. It's incremented in 1/3 stop intervals and allows for greater accuracy. Grade 2 will be about 10 gray steps instead of 7. Almost everything we do in photography is calculated in 1/3 stop intervals, so it kind of makes sense to be consistent there. I know that I can easily spot a difference of 1/3 stop exposure. While I think that 1/2 stop intervals are too coarse, the device is still usable. Anyway, you can find both types and more here.

 

[24x30]

I expect you will have problems seeing a differnence of 0,15 logD. 0,1 logD (31 steps) will not be easier . (maybe my eyes are not as good as yours).

If you make some teststripes, don't use linear steps. At a scale of 0-130 there will be less changes between 70-130. Most changes are between 0-40. The issue is just to find enough points of this curve to estimate results just by measuring and having a look at the curve.

rudi

 

[fschifano]

Not at all. I have both 31 and 21 step transmission density wedges and it's pretty easy to see differences of 0.15 logD when you make a contact print of the step wedge. These step wedges are not meant to be laid over a sheet of paper to determine how much exposure to use like the old Kodak Print Projection Scale. They are very useful for determining the speed point of a paper under different light sources and for determining how a given paper's tone curve changes in response to altered filtration. It can also be used very effectively for determining dry down effects, toning effects, in short, anything that alters the density and range of a given paper.

If you're making test strips, I absolutely agree with you that using a linear scale is close to useless and borders on being just plain stupid. In that case, making test strips with 1/2 stop intervals is plenty good enough. I like to do it by changing the time of exposure rather than altering the aperture. The formula for calculating f/stop based time intervals is: (base_time x 2)^(Number_of_stops_change). This works for any increment plus or minus you may wish to apply. To subtract 1/3 stop, the number_of _stops_change is -1/3. For adding 1/2 stop the number_of_stops_change value is 1/2. Works just as well for adding or subtracting in full stop increments. Plug the formula into a spreadsheet and have it calculate the factors for you. Print it out and paste it to the wall of your darkroom near the enlarger. PM me if you want a copy of my spreadsheet.

 

[clayne]

BTW Frank, if you don't already have a Stopclock Pro you might want to look into one.

 

[fschifano]

BTW Frank, if you don't already have a Stopclock Pro you might want to look into one.

I do fine with a standard old GraLab timer, a notebook, and a pencil. What I'll probably wind up gettng is Nicholas Lindan's Precision Enlarging Meter to replace the Jobo Comparator II meter that I'm using now.

 

[Smudger]

I do fine with a standard old GraLab timer, a notebook, and a pencil. What I'll probably wind up gettng is Nicholas Lindan's Precision Enlarging Meter to replace the Jobo Comparator II meter that I'm using now.

Just curious : I have the Jobo you mention (which I hardly ever use) - I'd be interested in your view of its strengths/limitations..

 

[fschifano]

I like it, and use it often. Save me a lot of wasted paper and really cuts down on any test strips I might need to make. Very often, it will nail down the exposure on the first shot, but the key is to calibrate it to your paper's speed under your enlarger. I use it in conjunction with the 31 step transmission step wedge. What it will not do well is measure accurately when there are VC filters in the light path because not only does the light intensity change, but the paper's speed does too.

 

[polyglot]

Piling in late here, but I use an LPL C7700 and it works great. The trick is not to try to replicate any particular grade and spend all day trying to figure out a new exposure time after changing the filtration settings... you just split-grade print instead.

Set full-magenta, time for the blacks. Set full yellow, time for the whites. Put both together, see what you get and adjust to taste. With a bit of arithmetic, you can figure out the mixer settings and time for a single exposure.

I can get about a grade 4 from mine; the only appreciable difference from the other (LPL 6700 I think) enlarger I have is that the B&W one is a condenser and the colour is a diffuser so that results in slightly lower contrast by default. Split-grade is difficult with most filter drawers because changing filters will subtly move the enlarger. With the colour head, you just tweak a couple of knobs and it's all perfectly stable.

Dichroic filters should not fade; they are glass with carefully-controlled coating layers that absorb (due to destructive interference of waves within the coatings) particular colours. Dust on the filters is another matter entirely.