Magenta colour cast from cheap ND filters

I bought a couple of cheap ND filters to play around with, and not surprisingly I suppose they cause a magenta colour cast.

To avoid this colour cast in future the simple answer is to buy good quality filters, so (a) which brand(s) are recommended, but (b) until I do buy replacements any suggestions as to how to remove the colour cast I get from the cheap filters (ideally in-camera - K20D)?

Thanks

You could try a custome white balance in camera, but try the various standard settings first to see if one does the trick.

Better, in Photoshop, certainly CS2 and later, there are Photo Filters, so you can colour correct quite easily from there.

In answer to your question Lee Filters are perhaps the most well known in terms of quality but they are not cheap. Formatt filters are also very good quality and I have used both of these brands. I think Formatt are a good balance personally in terms of price and quality. Whilst i was in the US in January this year, I was came across Singh-Ray filters, they looked to be very good but I did not purchase any, I don't know if you can buy them in the UK though.

I would also take John's guidance and try various WB settings or correct in Photoshop.

Fletcher8

Hi, you can't buy Singh-Ray in the UK, you have to order from US (B&H or Singh-ray direct).

One bit of advice when ordering Lee, ask the shop if they actually have them there in stock. There can be long wait times because a part broke at the factory.

Formatt is another name for Hitech filters, word on the street is they're good individually but there is colour casting when stacked. They are the only company other than Singh-Ray to do a reverse GND.

B&W in Germany are a good source for ND110. They don't do sheet filters, they're screw-on. Pricey but good.

Nass made a comment about the HiTech Filters having a colour cast when stacked, does anybody have any experience of this?

I already use HiTech ND Grads and am contemplating buying a HiTech ND1.2 (4 stop) to use with them, does anybody use this combination - if so what are the results like?

Cheers
LennyBloke

They do indeed. It's not unacceptable, and easily removed with a graduated mask in Photoshop.

Even my Cokin Z-pro filters will give some magenta cast when stacked, but definitely not as much as the HiTech ones.

That said, I'm using grads less and less - making more use of careful exposures and bracketing and sorting it out in Photoshop.



Another, very interesting approach, is "Tony's Magic Cloth" technique.
See here and a sample image here.
Definitely a technique I have to try when I have the time & energy

Matt

I have the Formatt/Hitech ND filters and they do give a magenta colour cast when stacked. It's at it's worst when a 4 stop ND grad is stacked on a 4 stop ND but the cast is a lot less than I was getting with the equivalent Cokin 'P' filters.

I've read a lot of discussion about certain sensors and sensor types showing a cast to a more or lesser degree with the same filters, so the suggestion is that some camera makes and models are better than others, though I've never heard any definitive proof of this. The theory is that the cast is being caused by light outside or at the fringes of the visible spectrum and some sensors are more sensitive to this than others.

I hope this comparison between ND grad filters (and colour casts) done by AP is of interest:

link

Tiffen did best, with most of the others showing some sort of colour cast.

But they do cost 5 to 10 times as much