ultrafine multigrade filter set

[Torquemada]

I purchased a set to use, have had a hard time getting my dichroic head in tune with certain brands of photo paper.

SO when i was using it, the results were way out of what they should have been.

Using the ilford comparison charts based on beseler dichroic filters,,, my contrast 2 filter from the kit, should have equaled my dichroic head set to 0-0-0..

but the results were more like my head set to 80 yellow- 0 - 0.. even when i used the 1.5 and 2.5 filters... they were still in the 80yellow + range in actual result.

Is this normal?

[Vaughan]

MG paper is sensitive to blue and green light. The blue sensitive layer is the HARD grade, the green layer is the SOFT grade. Red light makes no difference other than to the brightness of the image to our eyes.

Magenta filtration is blue+red=hard. Yellow filtration is green+red=soft. Combinations of magenta and yellow filtration make the in-between grades. Sometimes a bit of cyan filtration is added to give neutral density so the exposure times are consistent between filter grades.

I'm not into split grade printing myself, but you could in theory split the exposure time between magenta-only and yellow-only light to get different grades.

Note that MG filters were designed for tungsten enlarger light sources. All bets are off with cold (fluoro) and LED lights.

[Torquemada]

and im using a tungsten halogen dichroic head..

the thing is, i have no clue as to why a 2 filter would produce paper results identical to the head, built with kodak filters, set to 80 yellow -0 -0.. but the head itself set to 0-0-0 ie pure light, and a defined internationally recognized grade 2, actually produces a grade 2.

[Doremus Scudder]

and I'm using a tungsten halogen dichroic head..

the thing is, i have no clue as to why a 2 filter would produce paper results identical to the head, built with kodak filters, set to 80 yellow -0 -0.. but the head itself set to 0-0-0 ie pure light, and a defined internationally recognized grade 2, actually produces a grade 2.

... You shouldn't even need a set of multigrade filters if you have a dichroic head. Just use the filtration in the head. Ilford has a nice chart, which I think you mentioned you have. Filters are for enlargers that don't have color heads.

And, quit worrying about matching this grade to that filter to some arbitrary contrast number. Light sources vary in color temperature, filters fade, etc., et. Just start with no filtration; dial in more magenta if you need more contrast, dial in more yellow if you need less.

If you run out of contrast control on either end consistently, you need to develop your negatives more appropriately. If you're always using maximum yellow, develop your negatives less. If you're using maximum magenta a lot, develop your negatives more. Refine till most of your prints from "normal" negatives are within 20-30 units of no filtration.

Best,

Doremus

[Michael R]

and im using a tungsten halogen dichroic head..

the thing is, i have no clue as to why a 2 filter would produce paper results identical to the head, built with kodak filters, set to 80 yellow -0 -0.. but the head itself set to 0-0-0 ie pure light, and a defined internationally recognized grade 2, actually produces a grade 2.

There is no definition of any grade number. Also keep in mind the light source is an important variable when trying to match different filter sets or filter sets to dichroic heads. A halogen lamp does not emit the same spectrum as a regular incandescent lamp etc. Trying to calibrate anything for B&W work is largely a waste of time. Just use whatever settings get you to the print you want and ignore the numbers. As Doremus pointed out if you find you are consistently printing at minimum contrast or maximum contrast settings/filters you probably need to alter your film development times somewhat but other than that it doesn't matter.

[Torquemada]

... You shouldn't even need a set of multigrade filters if you have a dichroic head. Just use the filtration in the head. Ilford has a nice chart, which I think you mentioned you have. Filters are for enlargers that don't have color heads.

And, quit worrying about matching this grade to that filter to some arbitrary contrast number. Light sources vary in color temperature, filters fade, etc., et. Just start with no filtration; dial in more magenta if you need more contrast, dial in more yellow if you need less.

If you run out of contrast control on either end consistently, you need to develop your negatives more appropriately. If you're always using maximum yellow, develop your negatives less. If you're using maximum magenta a lot, develop your negatives more. Refine till most of your prints from "normal" negatives are within 20-30 units of no filtration.

Best,

Doremus

i was having problems with the ilford papers last year, i was getting higher grades of contrast then i should have gotten... i mean head set to 80 yellow - 0 - 0 was coming out equivalent to a 2 or 3 contrast setting on foma 313. I just wanted something "always in calibration" because id like to use ilford paper, but the damn cost of it

[Andreas]

Shortest and best explanation I have ever read of multigrade system, thanks !
Andreas

MG paper is sensitive to blue and green light. The blue sensitive layer is the HARD grade, the green layer is the SOFT grade. Red light makes no difference other than to the brightness of the image to our eyes.

Magenta filtration is blue+red=hard. Yellow filtration is green+red=soft. Combinations of magenta and yellow filtration make the in-between grades. Sometimes a bit of cyan filtration is added to give neutral density so the exposure times are consistent between filter grades.

I'm not into split grade printing myself, but you could in theory split the exposure time between magenta-only and yellow-only light to get different grades.

Note that MG filters were designed for tungsten enlarger light sources. All bets are off with cold (fluoro) and LED lights.

[Mark J]

Yes, very good.
Bear in mind that the exact 'grade' achieved, also depends on the colour temperature of the tungsten bulb - higher temperature has more deep blue content and hence a harder grade. Most enlargers specify a bulb over 3000°K .

[nolindan]

MG paper is sensitive to blue and green light. The blue sensitive layer is the HARD grade, the green layer is the SOFT grade.

Well.... I have to differ.

Both emulsions have the same contrast. Each emulsion contributes to half of the print's density. By controlling the relative exposure of the blue and green sensitive emulsions the HD curves of the two emulsions slide past each other. If the HD curves are on top of each other then the result is a high contrast print. If the blue light is attenuated then the HD curves combine so the low density part of the print is imaged with the green emulsion. The green emulsion plateaus half-way through the print and then the blue emulsion starts to contribute to the print's density and takes over until DMax is reached - in this case the print has low contrast as the combination of the two HD curves is now spread apart and the result is a combined HD curve that covers a larger exposure range.

See http://www.darkroomautomation.com/su...vcworkings.pdf (Sorry about the 'security warning' - I have to go into the site and change all the files around. A PITA that I have been avoiding for too long.)

and https://www.ilfordphoto.com/wp/wp-co...Multigrade.pdf

[Robert Bowring]

Doremus and Michael R. are correct. Stop worrying about some arbitrary contrast numbers. With variable contrast papers those numbers are irrelevant. You just need to know when to increase contrast or decrease contrast.