Would a magenta filter work for increasing contrast...

[Steven Ruttenberg]

...when taking bw image? Use it in place of say the red25A filter? Just curious.

[Gary Beasley]

It would darken the green colors. Any color filter removes its opposite color on the color wheel. A flourescent color correcting filter is magenta to reduce the greenish cast flourescents produce on color film.

[Pere Casals]

It depends on subject's color, if your subject is green then it will darken the subject in the image, rather than increasing contrast.

[Steven Ruttenberg]

True, I was just curious since magenta is used for contrast in printing or so I am told.

[Bob Salomon]

True, I was just curious since magenta is used for contrast in printing or so I am told.

That is because of the sensitivity of the paper emulsion. That is not the same as a film emulsion.

[Steven Ruttenberg]

Ok.

[Thalmees]

...
Use it in place of say the red25A filter?
...

For Pan films, I do not think it will replace(in effect) true Orange or even 21Orange, let alone the Red.
It will not act like photography filters.
For paper negative, I think it will do its job like in darkroom.

[Steven Ruttenberg]

Sounds good.

[Gary Beasley]

It would be good if you wanted to darken green foliage without excessively darkening skin tones or sky tones as it passes both those colors.

[Bob Salomon]

...when taking bw image? Use it in place of say the red25A filter? Just curious.

One big problem you would face is finding an optical quality one.

[Pere Casals]

One big problem you would face is finding an optical quality one.

Bob, not exactly pure Magenta, but tending to it, FL-W filters are easily found multicoated from top manufacturers.

The idea is using for BW a color correction filter for fluorescent lamps, to substantially darken green foliage in the background while keeping people's faces luminuous.

[Bob Salomon]

Bob, not exactly pure Magenta, but tending to it, FL-W filters are easily found multicoated from top manufacturers.

The idea is using for BW a color correction filter for fluorescent lamps, to substantially darken green foliage in the background while keeping people's faces luminuous.

Each filter manufacturer made their fluorescent (FL S is a Tiffen trademark, they had sent us a cease and disest letter when we advertised B+W’s version) to what each manufacturer considered the average color of fluorescent tubes. That is why one brand might work in one location but not in another while a different brand would have completely different results.
So just suggesting one is not a good answer.

Since you seem to like numbers go research the color temperatures of the different tubes. Back in the day Minolta did publish a list that filled two columns on 8.5x11” paper!

[Pere Casals]

each manufacturer considered the average color of fluorescent tubes.

hmmm, this should be the reason why FL-W filters vary...

In fact there are many flavours in fluorescent lamps, and for the same ºK we can have many possible SPDs ! Some tubes have horrible CRI...

[Steven Ruttenberg]

It sounds like there might be a use for using a magenta type filter for exposing the negative. Guess, the best way is to try it out and see how it works. 2 shots, 1 with, 1 without, maybe compare to a shot with a red, green and yellow filter as well. That would be fun.

[Bob Salomon]

hmmm, this should be the reason why FL-W filters vary...

In fact there are many flavours in fluorescent lamps, and for the same ºK we can have many possible SPDs ! Some tubes have horrible CRI...

Color temps also vary with tubes.

[Pere Casals]

Guess, the best way is to try it out and see how it works.

Just take a digital color image and use Photoshop to see the effects in the BW conversion, of course final result depends on light, film, filter and subject, but simulating it with Ps allows to understand the nature of the effect.



Color temps also vary with tubes.

Yes, of course, and this adds more troubles. Wedding photographers were scared by fluorescent lamps. I guess that today they are scared by bad LED lamps...

[Bob Salomon]

hmmm, this should be the reason why FL-W filters vary...

In fact there are many flavours in fluorescent lamps, and for the same ºK we can have many possible SPDs ! Some tubes have horrible CRI...

K is noted as K. Not °K!!

From Wikipedia:

“Before the 13th CGPM in 1967–1968, the unit kelvin was called a "degree", the same as with the other temperature scales at the time. It was distinguished from the other scales with either the adjective suffix "Kelvin" ("degree Kelvin") or with "absolute" ("degree absolute") and its symbol was °K. The latter term (degree absolute), which was the unit's official name from 1948 until 1954, was ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the plural form was "degrees absolute". The 13th CGPM changed the unit name to simply "kelvin" (symbol: K).[11] The omission of "degree" indicates that it is not relative to an arbitrary reference point like the Celsius and Fahrenheit scales (although the Rankine scale continued to use "degree Rankine"), but rather an absolute unit of measure which can be manipulated algebraically (e.g. multiplied by two to indicate twice the amount of "mean energy" available among elementary degrees of freedom of the system).”

[Steven Ruttenberg]

K is noted as K. Not °K!!

From Wikipedia:

“Before the 13th CGPM in 1967–1968, the unit kelvin was called a "degree", the same as with the other temperature scales at the time. It was distinguished from the other scales with either the adjective suffix "Kelvin" ("degree Kelvin") or with "absolute" ("degree absolute") and its symbol was °K. The latter term (degree absolute), which was the unit's official name from 1948 until 1954, was ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the plural form was "degrees absolute". The 13th CGPM changed the unit name to simply "kelvin" (symbol: K).[11] The omission of "degree" indicates that it is not relative to an arbitrary reference point like the Celsius and Fahrenheit scales (although the Rankine scale continued to use "degree Rankine"), but rather an absolute unit of measure which can be manipulated algebraically (e.g. multiplied by two to indicate twice the amount of "mean energy" available among elementary degrees of freedom of the system).”

I love science!

[Pere Casals]

K is noted as K. Not °K!!

True, this was the 1960s notation ! thanks for the correction.

[Thalmees]

I love science!
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.

It sounds like there might be a use for using a magenta type filter for exposing the negative. Guess, the best way is to try it out and see how it works. 2 shots, 1 with, 1 without, maybe compare to a shot with a red, green and yellow filter as well. That would be fun.
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.

[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.

[LabRat]

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.

Another interesting filter for night color is the filter sold for 35mm cameras, the Hoya Color Intensifier... There's two different shades (I don't remember which, but one peaks magenta, cuts green, and deep blues light polluted night skies)... I also use these for astronomy large eyepiece WA viewing to cut light pollution...

I think these might still be available, but were targeted to the amateur market with the common thread sizes and diameters...

Steve K

[Steven Ruttenberg]

There are filters that block sodium light for astronomy that I am going to try in the future for night time photography and see how that works.

[Steven Ruttenberg]

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

I will give it a try. Need to get a magenta filter first, shouldn't be terribly difficult to get a good used one.

[Bob Salomon]

I will give it a try. Need to get a magenta filter first, shouldn't be terribly difficult to get a good used one.

It is for an optical quality one!

[Steven Ruttenberg]

I used them in the past with film when I was shooting 35mm in doors under fluorescent lighting. Worked great, don't remember any issues, but that was almost 20 years ago. Don't remember paying much for it.

[Bob Salomon]

I used them in the past with film when I was shooting 35mm in doors under fluorescent lighting. Worked great, don't remember any issues, but that was almost 20 years ago. Don't remember paying much for it.

They were a combination of red and blue, how much depended on the manufacturer of the filter you used and the type of tubes used in the room. That particular combination will be very hard to duplicate and, if shooting outdoors, the K temp will be different.

[Drew Wiley]

I have a selection of deep magenta and violet Wratten filters for specialized mask exposure applications in the lab. I have no use for them in the field, and they're too expensive and fragile for that kind of usage anyway. I've sometimes used mild CC magenta filters in indoor architectural shoots, per color temp meter specifications.

[Steven Ruttenberg]

I will get a filter, then post up. Then from there I will experiment and post up as I do.

[LabRat]

There are filters that block sodium light for astronomy that I am going to try in the future for night time photography and see how that works.

Those filters are very expensive and usually small diameters, and would turn the moon cyan if you looked at it through a telescope...

The Hoya I mentioned is a dichroic filter not really different from them, but at a much lower cost... So worth a try...

They balance night color surprisingly well, but some stuff turns cyan or other colors...

Steve K

[Steven Ruttenberg]

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

Sounds unsettling. Green mafe facial blemishes stick out like a sore thumb.

[Steven Ruttenberg]

Those filters are very expensive and usually small diameters, and would turn the moon cyan if you looked at it through a telescope...

The Hoya I mentioned is a dichroic filter not really different from them, but at a much lower cost... So worth a try...

They balance night color surprisingly well, but some stuff turns cyan or other colors...

Steve K

The ones am referring to come from Astronomik and are.made such that tbey are balanced for o servational astro omy or photography.and will have little if any color shift according to the maker. Plus they can be had I believe in 100mm square filters, attach to image sensor in divital camera and can be made with almost any filter ring size. According to them you can photograph the heavens and planets well with them. I want to try them for bw pbotography to tame the sodium vapor lamps along the streets.

And yes, pricey like 180 for filter to go over camera sensor.