ND Filter affecting Color Saturation?

gco

gco

Veteran
Had a major "Duh" moment this weekend and I am wondering if anybody can confirm that I am understanding this correctly or not. Haven't found this topic discussed before.

I have been noticing that there are times when the color in my lcd screen looks desaturated. I finally figured out that it is happening when I switch from the 1/8 to the 1/64 ND filter. For example; say my exposure gets to f16 at 1/8 ND-- the color is looking full and saturated like I want it. Then zebras are telling me its time to cut down the light and I switch it to 1/64 ND and open up the aperture to f5.6. Even though the lens provides best resolution at f5.6, the color definitely looks desaturated with respect to the previous exposure setting--very disappointing. The effect is definitely there as I can clearly see it on the recorded footage.
Now that I have actually thought about it, it seems to make sense that you would see an effect on color saturation if you decrease the intensity of the light entering the lens via ND filter. When adjusting the aperture, the intensity (I think) remains the same; you are only reducing the area of the light source coming out of the lens and onto the sensors.
So the bottom line would seem to be; Increasing ND Reduces Color Saturation.
Am I understanding this correctly or is there more to it?
 
From what I have heard around hear, ND do not affect the color at all. I feel that they change it slightly, but when I watch my footage I really can never tell when the nd is on of off.
 
Yeah, ideally I would not want saturation to change at all but it does or at least it seems to. Something is happening.
What about white balance?
Seems like that should be consistent as well because you are only affecting the intensity not the color temp.
Something is definitely happening when I switch and its confounding the hell out of me.
 
I have found the ND built in or on the lens do not change the color temperature. They do however affect saturation slightly. In fact, as luminance decreases, perception of saturation increases and vice versa.

Don't take my word for it, try it in your NLE - increase the luminance and the colors look washed out, decrease the luminance and the colors look almost garish. (when color correcting, always adjust saturation when adjusting luminance...) Video Cameras usually adjust for this based on perfect exposure - too little exposure and the sat will be high, too much exposure and the sat will be low.

Back to your original response, there is a definite color shift if you stop the internal ND on an HVX in between settings. There is also an extreme color shift as you stop down an external 35mm lens.

Do you use auto white balance? If so, that could be the culprit of the color shift.


J
 
It would be interesting to see the difference between a 4x4/screw on ND, built in ND and just using the iris... maybe when I get some good ND's I'll do a little comparison.
 
AwakenedFilms said:
I have found the ND built in or on the lens do not change the color temperature. They do however affect saturation slightly. In fact, as luminance decreases, perception of saturation increases and vice versa.
Don't take my word for it, try it in your NLE - increase the luminance and the colors look washed out, decrease the luminance and the colors look almost garish. (when color correcting, always adjust saturation when adjusting luminance...) Video Cameras usually adjust for this based on perfect exposure - too little exposure and the sat will be high, too much exposure and the sat will be low.
Back to your original response, there is a definite color shift if you stop the internal ND on an HVX in between settings. There is also an extreme color shift as you stop down an external 35mm lens.
Do you use auto white balance? If so, that could be the culprit of the color shift.
J
Click to expand...
I'm quite certain the ND switch is not settling between switch positions. White balance method is strictly manual and I do this about every 15-20 minutes.
I shoot events outside and the action is pretty fast paced. I have seen color shifts due to white balance when changing the camera angle 180 degrees as I would expect. However, what I am observing happens when switching from 1/8 ND @ f16 to 1/64 ND @ f5.6+/-.
At this point I think I need to field test it and talk myself through the changes then watch it and see if that does not shed some light on it.
Thanks for the feedback AF!
 
After filming a video on a very bright day, I had the ND on. After reading this thread before I looked for a change, there really is not a very noticable change. Looking at the colours they still looked vivid and had good saturation. If you are worried about the colours then play around in the Scene Files and get some back.
 
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