kenzlenz Loc: Western North Carolina

This week I was shooting a waterfall using a 4 stop ND filter. When I got to looking at the RAW files I found a purple tinge on a number of them. What causes it and how do I correct it in PS?

Screamin Scott Loc: Marshfield Wi, Baltimore Md, now Dallas Ga

Sounds like a case of Chromatic Aberration. Purple fringing is when you get purple color in high contrast boundary areas in an image that was most likely taken in low light situations with a brighter background. Can be fixed in post (Lightroom and I'm sure other programs) and it can be mitigated by stopping down your lens when taking the image

jeep_daddy Loc: Prescott AZ

I know you said "tinge" and not "fringe". So what that really is is "color cast" that is often a problem with many filters. Some will inject a green, or blue or even purple color cast. What you can try is, first, shoot in raw so that you have more leeway when it comes to post production or post processing. Then in post, try a simply adjustment of the w/b (white balance) slider. If that doesn't work, try a white balance fix with the eye dropper. If that doesn't work then you'll have to learn how to balance colors using an adjustment layer. That's a little more complicated to get into here and a youtube search might be better to learn from.

kenzlenz Loc: Western North Carolina

Color cast is the right term. I tried the WB dropper in ACR and also tried adjusting the WB slider....cast is still there. I typically shot in Auto WB but happened to shoot in Sunny.....would that make a difference?

MT Shooter Loc: Montana

Actually a common problem with ND filters, especially cheaper filters that are not TRULY neutral.
When shooting on raw it can be corrected by adjusting the hue to get the actual colors back. Best choice is a better quality filter in the long run.

kenzlenz Loc: Western North Carolina

What brand would you recommend..I spend about $100 ea on the 4 stop and a 10 stop...

Screamin Scott Loc: Marshfield Wi, Baltimore Md, now Dallas Ga

What filter size and what brand were the ones you used?

MT Shooter Loc: Montana

Unfortunately price does not equate to quality, only to the PERCEPTION of quality. I use VU ND filters, Schott glass from Germany and truly neutral. Breakthrough also makes truly neutral ND's. Tiffens NATural ND filters are also great. I have found B+W to have a slight purple caste, but the worse by far are the Lee and Singh Ray "organic" products as well as their knockoff brands, and all plastic ND's like the Cokins.
Also try not to use Auto WB, its seldom reliable when using any ND product.

kenzlenz Loc: Western North Carolina

The filters that I use are the Vu ND filters. What WB settings would you use in this case?

MT Shooter Loc: Montana

I use whatever WB matches my lighting. If in doubt I use a preset based on an 18% grey card.

DanielB Loc: San Diego, Ca

Sample image would be helpful but it's most likely your ND filters color cast. If you use Lightroom use HSL adjustment choose saturation and/or Hue and back down that color in post.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Post a sample or two.

A magenta "tinge" is different from chromatic aberration. Depending on where you see the "tinge" it could be any number of things, but I will put my money on a color balance issue that would be there even if you didn't use the filter. If you have a mix of forest canopy and sunlight in your scene, the overwhelming color will be light filtered through the canopy, and sunlit areas will have a magenta cast.

The last thing I would consider is a problem with the filter, all of which will have a color cast, from cheap to ridiculously expensive. If there are no other aberrations, there is little benefit to spending a lot of money on ND filters.

https://fstoppers.com/bestfiltertest

There is a lot of mythology attached to ND filters - and testing will illustrate that there is no basis to the rationale of spending more being equal to getting better - at least as far as color cast is concerned.

If you shoot raw and use average white balance, it is easy enough to correct a color cast in post processing. But if you have two different color light sources, that will be a little harder, but not impossible.

camerapapi Loc: Miami, Fl.

Go Breakthrough filters. Very neutral colors.

BruceS

Cover the eyepiece during the exposure

wds0410 Loc: Nunya

Breakthrough filters are great. Pricey but worth it.