I have found that I need to use a ND filter on most of my footage and I decided to buy the polarised version as I do a lot of flying over water.
Does anyone know if there is any quick way to remove the colour cast that I get sometimes from the Polar Pro Cinema range of filters ?
I am learning to use DaVinci but have not got to the colour grading section yet. I have also read about LUTS and I wonder if any have been made for these filters ?
Finally, am I right in thinking that it would be sensible to remove any colour cast before adjusting the white balance to get a natural look ?
If by color cast, you mean the yellow/brown ish tint the ND filters create, I combat that look by using the Custom Kelvin scale in the app. Instead of simply selecting Sunny or Cloudy when setting a white balance, select the Custom Kelvin meter, and move the toward 3200 Kelvin to cool the image. I find that 4800 works reasonably well. Of course it depends on the time of day.
I believe the DJI default is 7000 (maybe it's 6000) both of which warm the image, which the ND filters then exacerbate. Therefore, move the meter toward 3200 to cool the image. Don't over do it, or everything will look blue even in the golden hour.
When doing this, it's best to launch the drone straight up before adjusting the scale. after launching, just let the drone hover while you fiddle about adjusting the scale to your liking. It won't take long. To get the feel for it, adjust the scale all the way to 3200, and notice how blue everything looks. Then move the cursor all the way to 8000 (?), and notice how yellow/orange everything looks. Supposedly, 5600 is natural light, and 3200 is tungsten. It's seems counter intuitive to move toward tungsten to cool things down, but realize this is to counter the effect of each light source. tungsten yields a very yellow/orange look. So, moving the cursor/slider toward 3200 is the effort to counter the yellow/orange look; hence everything is cooled down toward blue.
Look for something white in the image. This can be a car, a house, or other. As you adjust the scale you want what is white to look white for that time of day. In the golden hour, white is not white like paper. It looks golden.
Remember, this is an art. DJI tries to help by giving pre-determined settings such as Sunny, or cloudy for white balance adjustments, but you have greater control using the Custom Kelvin function in the app.
I've been using Davinci for a couple of years, now. In the end, post production can save an image, or really mess it up. The goal is to achieve the best look "in camera". you really only want to tweak in post. Many people use a flat profile when filming such as D-Cinelike, or D-Log. both of these reduce contrast and saturation. In post, you simply increase contrast and saturation. The difference is the degree of flexibility a flat profile affords. Realize that prior to post, a flat image looks terrible. However, it is easier to raise contrast and saturation than it is to dial it back; especially contrast. This is because dialing either back creates odd or not natural looking images. Its hard to describe but easy to see.
I do not like LUTS. LUTS are created by someone using color grading software like davinci. Under specific circumstances, they dial in a LOOK that works for that particular footage. They then try to sell it as if one look fits all when in fact it will not. The other issue with LUTS is their hard to adjust baked in finality.
By the way, LUT = LOOK UP TABLE. Basically, a table of "looks". Most are designed to work with specific camera processors.
good luck
