Red Filter Effect On "Non-Sky" Portion Of Scene/Photo

If the red filter is making skies darker and clouds 'pop-out', what's happening to what's beneath or in the foreground - green foliage, streets W/people, buildings, waterways, etc.
I always thought a polarizer was the way to go but is a red better...?

Spend some time looking through a red filter and see. The complementary colors will darken, similar colors lighten. Kodak used to have publications out about the effects of color of filters on black and white film.

I came across this once and find it a handy reference.

Very interesting... never saw that depiction before!

It’s nice... of course some days scenery is just full of things with low saturation. So sometimes filters don’t do as much as you wish

BrianShaw said:

Very interesting... never saw that depiction before!

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Of course, different emulsions have different spectral sensitivities, but I find it a good general guide.

Pieter12 said:

I came across this once and find it a handy reference.

View attachment 248222

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This one is very helpful! But it's important to remember this assumes 100% saturation. For example foliage will not reflect only green light, so it won't be completely black with a red filter, same goes for blue skies in many climates, as recently discussed in another thread.

DF said:

If the red filter is making skies darker and clouds 'pop-out', what's happening to what's beneath or in the foreground - green foliage, streets W/people, buildings, waterways, etc.
I always thought a polarizer was the way to go but is a red better...?

Click to expand...

What the above chart basically shows is that for B&W film, filters lighten their own color relative to the colors opposite of them. Yellow, red and orange filters will darken blues more than other colors. So think colors, not objects or things like the sky. A red filter will do nothing for a cloud-filled sky (no blue sky showing to darken).

One of the 'dangers' of red filters is that if you have large open shadow areas -- those areas are being lit be the blue light from the sky (instead of the more yellow light of the direct sun) -- so a red filter will bring the blue sky down in tone, but also bring the shadows areas down since they are illuminated by blue light.

I use yellow filters in the fall to pop out the yellow leaves in the redwood forest.

BrianShaw said:

Very interesting... never saw that depiction before!

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Yes, thanks Pieter12, a new one on me but once I got my head round what it was showing it is interesting and useful. Each colour has a light and dark square except yellow which is only one colour - perhaps this is the one colour where a differentiation between light and dark isn't helpful?

pentaxuser

In my experience, a yellow filter will darken saturated blue much more than is shown in the chart (compare to the "no filter" column; there's barely a difference in the chart...).

It helps me to think in terms of basic colors and their complementary opposites, i.e., red is the opposite of cyan (blue-green), green is opposite magenta (red-blue), and blue is opposite yellow (red-green). Other colors are combinations of the above.

A yellow filter, for example, passes light from red through green, eliminating blue. A red filter passes only red, eliminating everything blue and green (cyan) and so forth.

An orange filter is somewhere between yellow and red, i.e., it passes red and not-so-much green, so it darkens green a bit, but not as much as red.

A Wratten #11 filter (X1) looks green, but is actually "yellow-green," meaning it eliminates some red as well as blue.

It also helps to keep in mind that filter transmission spectra are not always "sharp cut." A weak red filter might look red, but passes a lot of everything else, just mostly red, whereas a #25 red sharp-cut filter will pass very little of anything else besides red.

A look at the Wratten filter designations and descriptions on Wikipedia is well worth the time.

Best,

Doremus

Doremus Scudder said:

An orange filter is somewhere between yellow and red, i.e., it passes red and not-so-much green, so it darkens green a bit, but not as much as red.

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The important part to me is that, as the chart posted by Pieter12 shows, an orange or yellow filter increases the contrast between light (usually more yellowish) and dark (usually more blueish) greens.

Green and green/yellow and even blue can be very flattering for portraits of woman and children. It will make them look dainty and accentuate red lips, cheeks and eyes and eyebrows.