How do you correct the color tint of a VND?

[jase]

Maybe a somewhat stupid question, but most VNDs add some kind of color cast / tint to the image. How do you guys handle this in your workflow? My initial idea was to shoot a white wall with and without the VND, create a color correction until both images are identical and then always apply this correction to all clips, subsequently? Is this correct or am i missing sth?

[jonpais]

In Final Cut Pro, you can use the color match feature, then adjust the sliders a little bit to get a very close match. Maybe some will frown on that though.

[AaronChicago]

It's tough. That awful brown tint is hard to fully correct. Tiffen makes and IR Variable ND, which reduces a lot of the IR pollution.

[Shirozina]

I set a custom WB before every take using a grey card or expodisk. This includes when changing lenses as these can have different color casts and same applies when I use a VND. There are several reasons you want to nail WB during capture and not leave it to post;

1, Unless you have a very good codec you will potentially loose image quality when correcting in post - this applies to low bitrate 4.2.0 8bit highly compressed internal codecs.

2, If you are using ETTR as an exposure method and you don't have WB set perfectly you can be clipping in a blue or red channel and not know it as most if not all zebra systems use the green channel and unless this is aligned with red and blue ( ie correctly WB'd) it won't show clipping in blue or red.

3 How will you know 100% from your footage what had the VND on and what had it off - extra hassle and time in post.

 

[Mattias Burling]

A good variable ND ads little to no tint. So personally I do nothing to correct for it.

[jonpais]

It sounds to me like Jase’s don’t match and is looking for advice.

If Jase is shooting Cinelike D and reduces saturation by -3, there shouldn’t be a problem with clipping. The codec is robust enough to handle matching shots with and without a filter. It is quite easy to see the tint on shots where a filter has been used.

[jase]

I am in the process of buying the SLR Magic VND which seems to be a good one, yet reviewers are telling about a tiny green tint and I was just asking myself how to correct this in general. In the end, i will just try

[AaronChicago]

@jase Which camera are you using? Blackmagic is the worst with ND IR pollution. I always have to use an IR filter. Canon and Panasonic both seem to get away with little variable ND color shift to a degree.

[maxotics]

I don't know if this applies, but something to think about.  A camera sensor is not sensitive to each color (filter) the same.  It's more sensitive to green, so green will clip before red and blue meaning that if the camera can't adjust for it you can end up with a magenta cast in the clouds say (because the red values are higher relative to the clipped/max green values).  Even in photography, the problem can be somewhat incurable in the wrong lighting.  My guess is that VND filters also transmit each wavelength differently so create havoc with the camera's ability to white balance.  So another test you might do is trying different strengths of ND to see which create the least/most cast.  Also, my guess is that my favorite, LOG gammas, will further exacerbate this problem.  

 

[Thomas Hill]

I used a couple different strength non-variable B+W NDs on a project with the Fuji X-T2 and had no color shift. Looked great. I haven't tried their VND though.

[mercer]

The B+W Vario ND is amazing. Very neutral... little, if any, color shift and I love the hard stops. Plus it has a special coating that helps keep the filter clean.

I primarily use cheap Bower Variable NDs because they are also known to be very neutral and they also have the hard stops... plus they’re cheap... so if you ever scratch them or drop them... just go and buy a new one.

But I am searching for the B+W Variable NDs for some of my usual focal lengths... 52mm and 77mm. 

I also have the SLR Magic and I notice a tint... it’s slight but it’s definitely there.

[JordanWright]

Do you find the B+W Vario ND better than the SLR Magic one?

[mercer]

I used them with different lenses, but I like it better. The SLR Magic is really well built and it has a cool handle, but I feel it is somewhat over engineered and there is a slight tint, I don’t notice with the BW. Most people love them though, so...

[webrunner5]

Anyone seen or used this brand of ND filter? The No X Effect part is the most interesting to me.

 

http://en.nisifilters.com/circular-nd-filters#VND

[Cinegain]

Heard, yes.

Sidenote, should one be looking for squared/circular fixed value ND filters... I'd say Breakthrough Photography now.

[jonpais]

@Cinegain Those look pretty awesome.