Dichro equivalent of Multigrade filters

nworth submitted a new resource:

(there was a url link here which no longer exists) - Dichro equivalent of Multigrade filters

Several posters have asked about dichro settings equivalent to the Multigrade filter set. It recently occurred to me that it would be easy to measure these using a color analyzer. The idea is to measure the magenta and yellow values for the filter and then to set the dichro filters in the enlarger to the equivalent values. Here is how it works in practice.

1. Turn on the enlarger and color analyzer, and let them stabilize for a few minutes. Place the analyzer probe in the center of...

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(there was a url link here which no longer exists)

Which enlarger? Which color head? MG filters are designed to use with standard enlarger lamps, you get different values, even using halogen lamps, slightly different color temperature. Most of the time you get a 2-2.5 contrast without filters, add magenta for more contrast and yellow for less contrast, exact values are meaningless, just write down the setting you used on your head for repeatability.

The measured values for the 4 and 4-1/2 filters seem odd compared to the 3 and 3-1/2

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I have also measured the current 4 and 5 Ilford filters with a color analyzer and don't think the filters are magenta and yellow. Perhaps the current 4 and 5 filters are using some narrow-band filtration. They look like 'salmon' color and certainly don't look like magenta and my eye (compare with the out-dated set below). Either way, I use the magenta/yellow information Ilford's own PDF here:

Dichroic equivalents based on Ilford's testing here: http://www.ilfordphoto.com/Webfiles/2010628932591755.pdf


Older set:

I don't bother with trying to find an equivalent. I just dial in more or less Magenta or Yellow as I think fit and it works perfectly and is just so easy. Ilford have this option in their Multigrade Contrast PDF file

Of course if you want to make comparison prints at various grade that method doesn't work as exposures differ so then I would use Dual filtration as per the second chart in the Ilford PDF.

ic-racer I have two or three older stets of MG filters from wnen the dye sensitisation was the other way around Magenta was soft, Yellow was for Contrast These are from the second release of Multigrade after WWII long gone by the time I began printing. Renwick of Ilford devised Multigrade before WWII but the outbreak of the war delayed actual production so DuPont's Varigram was on the market first, actually under licence from Ilford. Renwick had been seconded to DuPont in the early 30's as the two companies had close trade links.

Ian

Having bought a new set of MG filters recently they certainly don't seem to fit the yellow to magenta progression in looks. I note that nworth's dual filtration settings differ markedly from Ilford's. I wonder why this is and how do we reconcile the difference? Does it indicate that the MG filters are indeed different from the mixture of yellow and magenta found on a dichroic head?

nworth, can you confirm that your settings do give an equal progression from 00 -5. Do your settings avoid any change of exposure from 00 to 3.5? Sorry if you feel the answers to my questions were clear in your article but I just wasn't sure

Thanks

pentaxuser

Well a modern Ilford MG filter set has an ND bias so most print for the same exposure time so you won't see the extremes of dialling in filtration or the earlier filter sets.

Ian

pentaxuser said:

Having bought a new set of MG filters recently they certainly don't seem to fit the yellow to magenta progression in looks. I note that nworth's dual filtration settings differ markedly from Ilford's. I wonder why this is and how do we reconcile the difference? Does it indicate that the MG filters are indeed different from the mixture of yellow and magenta found on a dichroic head?

nworth, can you confirm that your settings do give an equal progression from 00 -5. Do your settings avoid any change of exposure from 00 to 3.5? Sorry if you feel the answers to my questions were clear in your article but I just wasn't sure

Thanks

pentaxuser

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The filters I used were about 8 years old, but not used all that much. But filters do age, and the manufacturer changes the filters to match the current sensitization of the paper. The values I got were for my filters with my enlarger and its halogen lamp. Others will certainly differ and may differ significantly. The reason why there are both magenta and yellow components in the filtration is probably to equalize exposure. But that does not work perfectly. Differing lamps and differing papers give different exposure results, but it helps. You always tweak the final exposure anyway.

The filters do not give an equal progression in contrast fro 00 through 5 (even with Multigrade paper), so the settings certainly won't. As I said, about the only thing you can count on is that the higher numbers give more contrast than the lower ones.

I use the filters only with my 35mm enlarger. For larger formats, I use Ian's method: I set my best guess according to Ilford's simple filtration guide and tweak it to greater or less contrast from there. Ilford's simple guide gives just a yellow or magenta number for various contrast grades, and the exposure varies quite a bit from grade to grade. I usually have to fuss with the exposure more, but I manage. Once again, the grades listed for the filtration do not correspond to actual paper grades and are not equally spaced, but they serve as a starting point.

I just follow the instruction sheet that comes with each Ilford paper package. I usually use the two filters but sometimes I just go crazy and use the one filter recommendation. It is all good.

Personally I don't bother with paper grade equivalent settings. If a test print needs more contrast I just dial in more contrast. I would image that others do the same. I have also used VC papers for which there is no data using this method.

Depending on the negative and the print, I often end up with filter settings between the grades. It is all about the finished print so I do not get concerned if I end up using a 2.3 or 3.1 filter setting. That is one of the beautiful things about using dichroic heads instead of individual filters.