Are colour filters really a waste of time with digital everything?

[dreed]

Reading through the start of Ansel Adam's "On the making of 40 photographs", the mention of the use of the red filter started me thinking - does the application of a "red" filter in software result in the same photograph if you used a red filter of a wavelength that matched the colour used in software? And the question should be asked especially if B&W photography is your forte.

[michael]

In a word - yes.

There's no need for color filters when shooting B&W with your DSLR. If you use Lightroom, for example, just convert to B&W and change the tonal values of any color for exactly the same effects as if you used filters with panchromatic film.

Michael

[neile]

What Michael said. And if you are coming from the B&W film world (and even if you aren't!) Nik Silver Efex Pro 2.0 is a fantastic package for B&W conversions. For your specific question it actually has built in presets for each of the traditional colour filters you'd use in the film world (with plenty of options to customize how they're applied, of course).

Neil

[hjulenissen]

Cameras use broad bandpass filters in front of each sensel to emulate the response of our vision.

If you scene contains objects that have very irregular spectral content, and you use color filters that have very irregular spectral response, you may get images that are impossible to do in photoshop.

For instance, two objects could have quite different spectral response but appear to have the same color to us humans, and an ideal camera would also render them with the same color. In this case, there is no difference for Photoshop to work on. In the extreme case, think of multispectral imaging: place 24 narrow passband filters in front of your camera one at a time and take 24 images of a scene. The 24 images will then contain more information about the scene than what can be obtained from a single non-filtered shot.

For most practical purposes, I guess that the experienced photographers here are right.



-h

[jonathanlung]

I haven't used a colour filter for this before, but could it come in handy for maintaining detail in a brightly (single-)coloured area in a (digital) B&W shot that would otherwise cause clipping? I don't do much floral photography, but I could see colour filters coming in handy.

[ErikKaffehr]

Hi,

I think that you are right, theoretically, but from a practical point we have a very broad range of manipulation with digital and raw formats. My experience is that filters are of little use, in general.

Best regards
Erik

Cameras use broad bandpass filters in front of each sensel to emulate the response of our vision.

If you scene contains objects that have very irregular spectral content, and you use color filters that have very irregular spectral response, you may get images that are impossible to do in photoshop.

For instance, two objects could have quite different spectral response but appear to have the same color to us humans, and an ideal camera would also render them with the same color. In this case, there is no difference for Photoshop to work on. In the extreme case, think of multispectral imaging: place 24 narrow passband filters in front of your camera one at a time and take 24 images of a scene. The 24 images will then contain more information about the scene than what can be obtained from a single non-filtered shot.

For most practical purposes, I guess that the experienced photographers here are right.



-h

[Jonathan Ratzlaff]

For black and white, I don't see any use for filters, what about colour correction.  In theory the use of an 80A filter could reduce clipping in the red channel in tungsten light.  This might make for a more realistic exposure of all channels, that could provide a better end result.   

[fike]

Put your color filters on your flash...just kidding, but to me, that is the only place where filtering or coloring light at capture time would be very desirable.  When you want to warm-up a scene, or you want to preserve a single color temperature to the light, gels are very useful on your flash.  The most common case is to gel the flash to match the ambient light (say fluorescent or incandescent) so that you aren't stuck trying to color correct for more than one color temperature. 

As for using a colored filter to selectively tone down highlights for B&W photos, I think you would be just as well served by an ND filter or more likely a polarizer.