How to reduce the nd filter warm color cast?

[brad goda]

like "hot mirror NDIR filters"

 

[brad goda]

use Fuji ND filter behind the lens.

 

[brad goda]

yah they are expensive...
Fujifilm made an extensive selection of durable wratten filters in 100mm size... lasted longer than the kodak filters but thin and flexible unlike Sinar acrylic 100mm filters... I know I have a full ND kit within my old filter kit... yah a whole pelican case full of blue yellow magenta cyan grads with holders from the good ol days ... like hundreds of dollars hand over fist of filters... glad my assist insisted NOT ebaying the case...

anyways if you can find fuji IR and ND maybe in Japan or EU... I am sure you can sandwich them together behind the lens...
should help with IR funk with ND but dont know about CA... UWA does create problems...

beginning of Digital we used to add blue 82, 80A 80B filters to take sensors into tungsten range...
we thought it was better than just pushing a button... how things have come so far... there are buttons for everything...(better blue sensitivity or overall better)
the old fisheye had internal filters... maybe canon will have to bring back something like this one day...

 

[Marsu42]

like "hot mirror NDIR filters"
use Fuji ND filter behind the lens.

Thanks for the information - these two pieces (hot mirror + gelatin nd) seem to be a solution for my 17-40L and the combined ndir for other lenses - though both outside my current budget. So I'll see how the "plain" 3.0 nd filter performs in the summer with more ir radiation - but good to know what the alternatives are, but the ir polution really seems to be an issue: http://www.tiffen.com/press_release_Hot_Mirror_IRND.htm

Btw: This page has a good discussion on fixed/vari nd filters concerning ir & uv leakage: http://www.dpreview.com/news/2011/8/12/heliopan82mmnd

Magenta casts and ND filters are usually due to IR leakage in the filter. This is common, most strong filters let a lot of IR through, and most older cameras register that IR in the blue and red channels, making magenta. A good "hot mirror" IR filter should clear it right up. And it will improve your foliage colors, too.

Every camera responds differently to variable ND filters (crossed polarizers, whether you cross your own or use something like the Heliopan) and also to actual ND filters. ND filters "leak" a lot of IR light. That's why crossed polarizers are sometimes used as improvised IR filters. Crossed polarizers have an additional problems that a "normal" ND filter, a single piece of dyed glass, won't have, in that they also leak UV. Cameras have good IR/UV blocking filters inside, but when you do something like blocking 8 stops of visible light, the leaked UV and IR start to cause problems. IR typically shows as a magenta cast, UV as a blue cast.

 

[neuroanatomist]

Doesn't have to be IR. if you look at the transmission curve for the B+W 3.0, it starts to rise from 'neutral' at about 630nm.

 

[Marsu42]

Doesn't have to be IR. if you look at the transmission curve for the B+W 3.0, it starts to rise from 'neutral' at about 630nm.

Um, is this the same with the Heliopan filter (I couldn't find the information through google, and the manufacturer seems to think otherwise)?

And if I understand you correctly you're saying "IR Polltution" cannot be a problem for these nd filters no matter the fuss about it :-o ? I'm asking because the websites I just read suggest that nd filters leak ir on long exposure shots no matter how the transmission curve is supposed to be, and the only and new (see tiffen 2008 press release) solution is a hot mirror filter.

 

[brad goda]

Doesn't have to be IR. if you look at the transmission curve for the B+W 3.0, it starts to rise from 'neutral' at about 630nm.

ok whatever you say but cinema guys I know all have full line up of hot mirror IR ND filter kits.
I guess they have spent thousands for nothing.

what do i know... live and learn

 

[brad goda]

marsu42
ok good you are finding the info to answer your problem! great info hunting!

 

[neuroanatomist]

Doesn't have to be IR. if you look at the transmission curve for the B+W 3.0, it starts to rise from 'neutral' at about 630nm.

ok whatever you say but cinema guys I know all have full line up of hot mirror IR ND filter kits.
I guess they have spent thousands for nothing.

what do i know... live and learn

Ummm...ok. :-\ My point was that it's important to know the transmission characteristics of your filter. With a B+W 110 and an IR cut filter starting at 700nm, you've still got some increased transmission from 630-700nm.

 

[Marsu42]

marsu42
ok good you are finding the info to answer your problem! great info hunting!

Thanks and maybe no surprise the manufacturer doesn't say: shooting with this filter will generate a color cast and lower contrast in high ir conditions, but you have to pay a *lot* more for the solution that fixes it and our stacked solution won't work for wide angle lenses at all so go and look elsewhere :-o

 

[brad goda]

neuro
got your point...
but in IR yes you do need to know transmission freq. near IR or far IR ... UV
which to block with which filter...
lucky some filter companies made stackable or all in one hot mirror NDs...

check it out.. this from tiffin...prices not as scary as others

http://www.tiffen.com/press_release_Hot_Mirror_IRND.htm

 

[GMCPhotographics]

Buy LEE or schnider optic.

Lee had some of the most variability in quality control and colour casts of all the filters I've tried their ND grads often have a purple cast in the darker densities. The B+W cast is very strong and like a copper tone. Very odd and quite harsh.
Heliopan are my preferred choice and offer more options in their range. I personally find their 5 stop to be the most useful. The Hoya 9 stop has a nice pink hue, which I really like too.