Super Chromega D Lamphouse Dichroic grade filter questions

[chris72]

Hi,
what filtrations have you use on Super Chromega D Lamphouse Dichroic II? The grades from the manual are from polycontrast filters:
No.1 35M - 24Y
No.1 1/2 42M - 20Y
No.2 50M - 16Y
No.2 1/2 100M - 8Y
No.3 150 M - 0Y

I know are 2 diferent way to use this, one is use only one filtration once, and second to combine the filtartion. Have you test to see ?

[Joe O'Hara]

The idea is that you can vary the contrast by using only Y or M but the exposure to keep middle gray the same will change. So I always use the two-filter method, using the values that Ilford provides in the package (I use MG Warmtone and MG Classic) for Chromega enlargers. In my experience the exposure for middle gray is pretty constant that way, and I can set grades from about 0 to 4-1/2. (One of the nice things about using a color enlarger is that you can make very small changes to the contrast, which you cannot do with plastic filters.)

Note that the paper manufacturer's values may differ from values recommended by Omega when using plastic filters. With Ilford paper, 150M and 0Y in my Chromega head is more like grade 4-1/2 (close to maximum contrast), as opposed to grade 3 as you have here. Other paper manufacturers may recommend different combinations with their products.

[ic-racer]

You can also use the table of filtration values included with Ilford Multigrade paper. That is what I use and the spacing of the grades is good.

[chris72]

Thank you for answer but how you determine the grade?

[LabRat]

I have seen charts all over the map about MG filtration for the grades, but in practice it's been much simpler...

I worked in many printing rooms, and the ones with colorheads, it always came out pretty close using these settings (for US calibrated head scales)...

Let's start with #2 contrast... There was 2 settings... Without filters, paper would naturally expose for #2 (with a deep bottom), or you could use 10M or 15M and get a #2, but with shadows that dont go as dark as unfiltered... #2 1/2 would be at about 25M, #3 would be at 40M, #3 1/2 at 60M, #4 at 80M, and #5 at 100M... To reduce contrast would be about 10Y for #1 1/2, and 20Y for #1... It always worked like that for most all papers, but there would be a time change (but fairly fixed steps that just required doubling the settings)...

It all comes down to being able to print in the highlights on the paper, then adjusting the "bottom" dark level where the shadows just print in... (You expose for the highlight, and adjust until the shadows on the neg just appear before paper's Dmax...) Remember there will be dry - down increase of density there...

The type of paper makes a little difference, as faster RC'S tended to get harder contrast a little faster, but a paper like FBWT gets sluggish after #3 filtering... You get the hang of it after a few test strips...

Papers never seemed critical to minor tweaks, more like a big, blunt instrument that minor tweaks to settings didn't matter until you at least doubled the CC setting from the previous grade step... Meaning, settings not critical (really), just set, and look at test strips, and maybe take some general notes...
So this tends to be one of the least critical parameters among all the other (more critical) points...

Don't make yourself nutz over the posted specs, it's much easier than that...

Steve K

[ic-racer]

Thank you for answer but how you determine the grade?

Easiest way is to contact print an inexpensive, uncalibrated 21 step wedge (0.15log d per step). Count the number of gray bands and that is the ISO(R). So, if you get 5 gray bands that is 5 x 15 = ISO(R) 75 which is about grade 2.5

The most common darkroom printing error is improperly processed or exposed negatives. Since ISO is defined as the minimum exposure to produce an excellent negative, statistically 50% of negatives will be under exposed and therefore may be difficult to print if you are using so called "Box Speed."

[chris72]

Thank you !

[Drew Wiley]

I keep asking, why do people even worry about this issue when actual graded papers are no longer involved, but VC, and you've got a continuously variable Y and M - ? It's a continuum in both respects. Guess it's like referring to horsepower long after the horse and buggy era, but in this case talking as if only discrete increments of horsepower were available. Yet if one had never even heard of paper grades it would be every bit as easy - maybe easier - to make excellent prints with a colorhead. I consistently ignore every bit of the quantified advice posted above, but routinely get some wonderful prints every darkroom session. And not every paper responds the same way to specific settings, so just how many magic formulas will you need to concoct to make sense of this.
You can go nuts with a calculator or program trying to factor in all the variables, or you can do it with your own eyes and a simple test strip in a few minutes, and probably do it better. If people enjoy number crunching methodology, that's fine too, but I don't see how it makes anything actually more efficient. Just sayin', and not trying to rain on anyone's parade.

[ic-racer]

This ISO R is useful for constructing the table, so one can space the contrast evenly across the spectrum. Otherwise the table is hard to use if the Yellow and Magenta numbers chosen cluster around the same ISO R.