In analog film photography, filters of different colors were (and are) pretty common. Red for darkening blue sky, green for lightening greenery, and so on. But what about colored filters on a digital camera, is there any point?
I was curious, so I googled a lot without finding a satisfying answer. So, I set out to find a filter or two, which turned out to be not so easy.
I found a Hoya green filter on eBay, figuring that I shoot many woodlands and landscapes with a lot of green color in them, so it might make sense.
Ilford explains the effect of a green filter on black and white film:
It lightens green foliage, which is particularly important with dark green leaves which can record very dark without a filter. It therefore gives a more natural, lighter feel to the photograph.
So, does it make any difference?
Here’s a simple shot of some ferns in our back yard, first without filter (JPEG, D800e):
Then same thing but with the green filter on it:
Then a RAW without filter converted to monochrome in Lightroom (no other adjustments):
And a RAW with filter converted to Monochrome:
Green is now much brighter, as we would expect.
Then I took the same RAW files as above but reduced green by -30. First the one without filter:
Then the one with filter:
And let’s finally look at the histogram for the one without filter:
And the one with filter:
Clear, difference, right?
Conclusion? Not sure the green filter does much when you shoot digital. Perhaps not a big surprise, but I feel it was still worth a try.
There is a noticeable difference in the green tones between the shots. After black and white conversion, green is lighter in the shot with the filter, as would have been the case with film.
But I also sense the filter separates different green tones from one another, and I think that is clear in the histogram, green stretches out over more of the histogram, and seems to stretch the entire tonal range over more of the histogram.
That may, I guess, indicate that a green filter may spread out the different greens in a shot, and make them more different from one another, if that makes sense.
I’m not sure I got that right, but I do know there’s more to explore here.
Obviously, this only matters if you are going to end up with black and white shots.
Next, I think I will try a red filter.