ND Filter Color Cast

[LePetomane]

How does one remove the magenta color cast when using neutral density filters? I was told that only the cheap ones produce it but I still see it with my Singh Ray filters and they aren't cheap. Thanks in advance.

[xpatUSA]

How does one remove the magenta color cast when using neutral density filters? I was told that only the cheap ones produce it but I still see it with my Singh Ray filters and they aren't cheap. Thanks in advance.

Reads like an info-mercial for Topaz but if it works ...

https://annemckinnell.com/2014/08/13...-colour-casts/

A lot of verbiage about a Cokin here ...

https://www.flickr.com/photos/brentbat/2372603825

Elsewhere I read that the magenta comes from the "neutral" density filter passing significant amounts of IR which get through many CFA's - thereby tipping the color balance toward magenta ...

[Manfred M]

Elsewhere I read that the magenta comes from the "neutral" density filter passing significant amounts of IR which get through many CFA's - thereby tipping the color balance toward magenta ...

Not just IR in some cases; the Lee Big Stopper has a well known blue cast that comes from the UV side, but basically a similar mechanism. The camera's IR and UV cut-off filters are not 100% efficient, so on long exposures this effect becomes more pronounced as more of those wavelengths get through. Different camera makes and models show differing amounts of this problem.

Correct the issue in PP is the only work around I know of. Some people with cheap filters have been known to only work in B&W.

[William W]

I use the Colour Correction facilities (usually Photoshop or Lightroom), during Post Production.

I find that process is not tedious, maybe I am either quick with experience, or simply too easily satisfied, or just too lazy.

The other point I've noted (and this is the main reason why I've not tried the plugins), is the nuance of the Colour Cast, whilst maybe being Filter dependent (I have several ND Filters), is certainly Shutter Speed dependent and with little adherence to any Reciprocity guideline, which makes me think that it is also Light dependent.

That's a convoluted way of saying that I expect that each individual Shot using an ND Filter to have its own nuance of Colour Cast - so "hand crafting" the correction, is my method.

WW

Thanks, gents for the prompt re IR and UV apropos DIGITAL sensors. I did have that knowledge in the back of my head, but never much gave it much thought, so I will, now.

[John 2]

William is right about the problem being condition dependant but you can reduce the problem to a large degree if your camera has the facility to set up colour balance pre sets. It requires a white opaque filter covering the ND. When I had a Nikon, this took the form of an inexpensive dedicated lens cap fitted over the ND and the camera then adjusted for a correct colour balance which could be saved. It is then only a matter of selecting the pre set when you want to use the filter. Haven't tried it since I moved to Fuji but you might find Sony and Fuji have the same capability.

[Manfred M]

s certainly Shutter Speed dependent and with little adherence to any Reciprocity guideline, which makes me think that it is also Light dependent.

Reciprocity was a "feature" in film photography. So far as I understand it, there is no impact in the digital world. Film had an "S-shaped" response curve, although for all intents and purposes it was linear through much of the exposure range with reciprocity only become a factor when shutter speeds dropped into the several second range and slower and at speeds above 1/1000th second. Digital sensors are linear.

[John 2]

Just in case it's of some help, this is the lens cap I have:

https://www.amazon.com/CamDesign-Whi...balance+filter

It comes in different filter sizes but I bought to fit the largest I use (77mm) and then used adapter rings if I needed to.

[antongorlin]

just get a better filter. Like Lee or Nisi. These magenta colour casts are very hard to get rid of.

[Polar01]

Have to kind of correct you, Anton, Lee 10ND filters have a blue caste, the B+W have a warm caste, they are as you would say better filters, I know as I have both of them.

Cheers: Allan

[DanK]

But not all NDs do. I have two Marumis that have virtually no color cast.

[Manfred M]

But not all NDs do. I have two Marumis that have virtually no color cast.

How many stops are your filters Dan? Usually the effect starts showing up once your get towards 10-stop and higher range. My 5-stop Tiffen, which is a mid-price range filter has no cast and neither do my 1, 2 and 3 stop Lee filters. I haven't done a lot of work with my 16-stop Formatt-Hitech Firecrest filter (same price range as Lee and NISI), but it seems to be reasonably neutral.

[DanK]

Manfred,

I am not at home, so I can't check, but both Marumis are well under 10 stops, I think perhaps 2 and 6. I have a Hoya Pro 10-stop that is quite neutral, but it has been criticized for reducing sharpness.

One can get color casts below 10 stops. I bought one Breakthrough filter that was less than 10 (I think 6, but I don't recall), and it had a distinct off-blue cast. I returned it, so I can't confirm the density.

[Manfred M]

Manfred,

I am not at home, so I can't check, but both Marumis are well under 10 stops, I think perhaps 2 and 6. I have a Hoya Pro 10-stop that is quite neutral, but it has been criticized for reducing sharpness.

One can get color casts below 10 stops. I bought one Breakthrough filter that was less than 10 (I think 6, but I don't recall), and it had a distinct off-blue cast. I returned it, so I can't confirm the density.

I agree that lower end ND filters can have a colour cast at any density. I once had a UV filter that threw a small but noticeable yellow cast, but these were all low end / no name brands. Poor manufacturing quality practices can definitely have this effect; some filters are real bargains and others are rather disappointing even when they are technically the same filter and from the same manufacturer. I know of one photographer who does his long exposure images in B&W because of the colour casts he gets from his cheap filters.

The higher end ones should, in theory, have higher quality, but that is not always (unfortunately) the case. I've also noticed the shutter speed dependence with filter performance that Bill mentioned in #4. To paraphrase Bill a bit, the longer the shutter speed the more noticeable the colour cast. This is unfortunate as the main reason people use these filters is to get long exposures...