Would a magenta filter work for increasing contrast...

[Steven Ruttenberg]

That's really good.
Photography as art, does not need very deep and specific knowledge.
Science imply clever expectations based on basic but robust knowledge.
Please read further.

So, what do you expect if you used two(2) light color filters stacked together?
One is light Red, the other is light Blue.
Do you think the Red part could darken greens like foliage?
Then, the blue will lighten the sky?
Something like the effect of pre-panchromatic films, may be 1800's century's plates.
That's the Magenta as I think. It has Blue, built in!
Please notice also that Pan chromatic films do not see like our eyes, and need a grade of Yellow(Y8-Y12) to see like human eyes. You are taking the film further away from our seeing nature if you use Magenta filter.
Photographic contrast filters, from light Yellow(Y5 or Y8) to true Red(R25) plus green filters, has a cut point(actually it's a zone, not point) at which, most of the shorter wave lengths lights, are blocked almost completely. Its effect on film is expected very well.
I could not imagine a similar curve for Magenta filter. Artistically, I do not feel well with the idea.
But, for testing, studying, special situations or just for fun, every and any assumption can be considered worth of trying.

I try not to fit into a mold. Almost in every case, even with my friends, photographs are only good if they follow this rule or that rule. Like digital folks will say you must expose to the right in order to obtain the most information in your image for ideal processing. That is a patently false statement. I have experimented and can expose for the shadows with digital and develop for the highlights in ACR for example in much the same way you would with film. That goes against all "conventional" wisdom. Rule of thirds is another rule that annoys me. There are occasions where it works, but many are like your image sucks if you didn't follow rule of thirds. In fact, I have one friend that produces every single image practically with rule of thirds.

I was curious about the magenta filter use as I used them in the past to correct for fluorescent lighting and even in photoshop when I didn't have a filter on and should have.

Science I do love, but it is only a starting point for the basics of understanding something. Practical application is a whole other realm. I know many who are science experts, but when it comes to practical application, well, they are like bulls in a china shop.

The way I do things is when I think of something, I then ask about it (no sense reinventing the wheel), hear all the advice, wisdom, bs, etc and then, if I decide to go farther, I try it and see what happens. Sometimes it works, and sometimes it doesn't. But you would never know if you didn't try.

Each filter, red, green, blue etc, is essentially a band pass filter and will pass the wavelength of light equal to its color and block out most other light the farther from its mean frequency or wavelength if you wish. If I use a magenta filter, I essentially block green and get red and blue light passing thru to expose the film to. This means I can block green and get the same or similar effect of combing two filters of red and blue. Is this worth anything? I don't know, but it is worth trying and if nothing else, just fun and educational, for me that is.

[andrewch59]

I am by no means a professional, but I have read on someones blog about the use of blue and green filters for b&w. Blue was used to increase contrast and green for highlights. I have only just bought the rosco filter set from b and h and haven't tried them yet, but it makes sense.

Using Rosco filters for Multi-grade printing?? this is a thread title on lfp which also delves into blue/green rosco filters

[Steven Ruttenberg]

I have used green and it is harsh on skin. It seems to reveal every little blemish and detail whereas the yellow is much softer on the skin. I have typically used red and yellow for most things.

[Gary Beasley]

The magenta will probably be soft on the skin as well. In the glory days of black and white portrature a light green filter was often used on male subjects to darken the skin for a more “virile” look. As magenta is the photographic negative of green it will have the opposite effect, might be just what you need to downplay blemishes.

[interneg]

If magenta filters had significant uses at the taking stage, they'd be much more readily available - there were/ are #32 & #33 Wratten gels for specific technical/ separation purposes, but rarely used for general photography.

[Steven Ruttenberg]

Well I will give it a shot and see

[Gary Beasley]

Post a few and let us see what you find out.

[Jac@stafford.net]

I have used green and it is harsh on skin. It seems to reveal every little blemish and detail whereas the yellow is much softer on the skin. I have typically used red and yellow for most things.

I have had terrible results with red filters where veins were shown that the eye cannot see, and does not want to see.

[LabRat]

Should lighten freckles on fair skin...

You will have to come up with a filter factor for your film, as many B/W films have a slight (but varying) peak in green...

Steve K

[neil poulsen]

I photographed a light rail train at night, and a 30 magenta did an excellent job of filtering the green in the on-board fluorescent lights. It also "magentized" the street lighting. But to my thinking, it was different, but not a negative in the photograph.