Alternative filters in the Enlarger

[Bayard]

Has anyone ever tried to use Rosco or Lee filters, outside the yellow/magenta range, in an enlargement? If so, to what effect?

I know that paper is blue-sensitive, naturally, and is made sensitive, through the use of dyes, to green, in different amounts on different layers. That is why the Yellow #00 gives us low contrast, because it blocks the blue light, allowing only the low contrast green dyes to work full time. Similarly, the magenta filters block different amounts of green light, letting only the blue through and, thus, increasing contrast.

My guess is that a blue filter would cause a high-contrast image, but with wicked fast exposure times, and a green filter would give a low contrast fast exposure.

What about other colors, either in the filter drawer or as a filter over a mag-lite, for flashing all or a portion of the paper? Anyone tried this?

Bayard

 

[Andrew O'Neill]

I use Roscoe filters with my 8x10 enlarger. The darkest green and the darkest blue filters. They work very well for split printing. I place them above the negative.

 

[silveror0]

Andrew's method may be less expensive, but here's my experience FWIW. After I recently converted my E6 Omega 5x7 enlarger (no filter drawer) to 7500K LEDs, I wanted to check it out using fresh Ilford MGIV paper. I used Ilford under-lens filters (no half grades) by projecting a 31-step wedge. I was curious to see how close I could approach what I considered the limits of the contrast range by placing blue and green color separation filters (47B & 58) under the lens. I found the Ilford filters did come very close to the limits, BUT the color separation filters were so dense that they required exposures so long as to be impractical, possibly a result of the lower intensity of the LEDs, IDK. The blue & green filters have Kodak-recommended daylight factors of 6x and 8x, respectively, but they might allow for lengthening your exposures. Just my 2 cents.

 

[MattKing]

By the way, you misunderstand how the two different emulsions in the multigrade papers work.
They are mixed evenly throughout the emulsion layer - they are not physically separated.
And the two (or in many cases three) emulsions don't offer different contrasts - they offer different speeds. The blue sensitive emulsion is more sensitive to light and builds more density more quickly with exposure. The green sensitive emulsion is less sensitive to light, and builds density less quickly with exposure. The change of contrast in a print is achieved in an additive manner by adjusting the ratio between how much of the fast emulsion and the slow emulsion components are exposed.
The Ilford (and formally Kodak, and other manufacturers) filters work as they do because there colour and density are designed with the relative speeds of the two (or three) emulsions involved). If you try to use filters designed for other purposes, their colours and densities may lead to unexpected results.

 

[Bob Carnie]

In the 80's we used Lee filters and lith negatives to make multiple colour mural prints and composites.. some quite basic one colour type to multiple image with colour surrounding .

One would find a normal black type balance for any paper and then lay down all the filters, by process of picking the colours you liked all the different lee filters could be used with the
single colour pack and be repeatable..

 

[ic-racer]

Any filter that interferes with the enlargers light spectrum in the green and blue areas will affect printing contrast. What effect to you want to achieve? Take the controlled spectrum of contrast, provided with the Ilford filter set and make contrast control more random?

 

[Bayard]

Any filter that interferes with the enlargers light spectrum in the green and blue areas will affect printing contrast. What effect to you want to achieve? Take the controlled spectrum of contrast, provided with the Ilford filter set and make contrast control more random?

Truly, I am just interested in seeing what would happen with non-standard filters. Whether or not I like the "look" of what I get will not be evident until I see the results, but if anyone has already done this kind of thing, why reinvent the wheel?

 

[Patrick Robert James]

You can use blue/green. You could even do blue/yellow, or magenta/green. Doesn't really matter.

I have a Saunders VCCE which uses dichroic magenta/yellow filtration in the light path. Works great. I also have a Focomat with which I use blue 47 and green 58 glass filters below the lens. That works great too.

I wouldn't use cinema gels in the image path (between the negative and the paper), only in the light path (between the light source and the negative). I threw a Roscoe gel into a pinhole camera once and the pinhole imaged the banding of the color in the gel!

The other consideration if you use blue47/green58 is the transmission of them. They actually are not completely transmissive in the wavelengths they let through, so the blue for example, does not let all blue light through. Magenta and yellow IIRC are completely transmissive. This only matters if you are doing huge prints or have a weak light source, but it should be mentioned.