Just a thought.
Just a thought.
So guys a lot of confusing responses here, but lets give a straight answer, is it blue or magenta for highest contrast when using multigrade paper?
Typical = halogen or incandescent or cold light? bulb.
Non-typical = blue LED with narrow spectrum filter to remove green - harder to make work.
The challenge isn't with the paper itself, it is with the systems used to control the light hitting it.
It is far easier to control green light with a magenta filter then it is to produce blue light that isn't contaminated with green.
And the excess red light that a magenta filter "transmits" improves visibility, without affecting the print.
It would be pretty damn difficult to design any automated system of exposure to predict all the variables. You'd have to settle on a single product, and then just about the time you think you have it
figured out, they'd probably tweak something in the emulsion. Even with Ilford, you've got different VC
products with different personalities, plus Kentmere VC products offered by the same corp. It would be
like trying to write a Zone System computer program for multiple film, developer, and lighting situations. You could spend years fiddling with something that only takes minutes with a simple test
Matt - it's super simple to pass blue without green. You just need a blue tricolor separation filter like
a 47 or 47B. Zero green gets through. Or you could hypothetically use the blue output on an additive
colorhead, though not many of us own those kind of rigs. The only logistical problem with a deep blue
separation filter would be due to having a hard time seeing the projected image when doing complex
dodging and burning under the blue light. I don't personally have this problem because even my cold
light is quite powerful. I have a 14x14 V54 Aristo which uses a single tube of blue-green, so works
wonderfully for split printing. Without any filtration, it lands VC paper around grade 3.
1) If you have a narrow blue light source (that has no green in it), the answer is to use blue light.
2) If you are filtering white light with filters, magenta is the answer, because magenta filters out the green and allows blue light to pass.
This is the simplest way to think about it. In reality paper sensitivities are not "sharp cutting" so there are subtelties. But not anything to really worry about.
Let me know if this makes sense or if it is still confusing.
You need to expose with more blue light to get more contrast with modern VC papers. The magenta filters pass both blue and red light. The paper is not sensitive to the red, but your eyes are, so the magenta filter makes the image easier to see. In a like manner, you need to expose with less blue light to reduce contrast. The yellow filters block some of the blue light and passes red and green. The green sensitive emulsion in the paper receives proportionally more exposure. The yellow filter allows you to see the image better.
For maximum contrast you can use a sharp cutting blue filter like Wrattan #47. You will have a very hard time seeing the image through this filter, but it usually gives a bit more contrast than the Multigrade #5. Blue filters designed for color work, like the 80B or the 82 series, pass all wavelengths. While they do increase contrast with VC papers, they are mot as effective as the Multigrade or Polycontrast filters.
Need more contrast? Change print developer, bleach back the print a bit after printing heavier, bleach-redevelop the neg, etc. (including developing more the next time). I don't think we should be using max contrast on VC papers that much anyway...