How to get black skies with a red filter

<p>Hello, i recently bought a Hoya 52mm Red 25A HMC Filter with the hopes of getting black and white pictures with black skies, or at least dark skies. I tried it out on my DSLR buy setting the camera to take pictures in black and white, and when I took pictures of the sky with the filter on, I got gray skies, and not dark or blackened skies. Does anyone know how I can get the effect of black or darkened skies with this filter. Can it be done with a DSLR or must I use black and white film?</p>

<p>Somebody once reminded me to set a fixed white balance, to keep AWB from spitting into the filter usage soup. - I have no clue what works on DSLRs in that field. - SLRs are IMHO the least attractive kind of camera for use with dark filters.</p>

<p>Before you do anything else, shoot some pictures on your DSLR in full color and then during processing back off the G and B channels, if necessary down to zero. This has two advantages, firstly that you can shoot at a true ISO 400 with no filter factor and secondly you can experiment with different filitrations rather than doing this in an "all or nothing" way during image capture. The attached picture was done this way.</p><div></div>

<p>I'm speaking from a position of ignorance here because I've never tried the exercise that the OP describes: however, I think Jochen is on the right track. Most people have their digicam set to auto white balance, and the effect of this is to try to compensate for whatever odd light conditions may arise - in this case the condition of everything turning red. So setting the white balance to normal daylight may allow the filter to do its stuff.</p>

<p>In principle you shouldn't need a red filter with a digital camera: the sensor has red, green and blue filters built in, and (as <strong>David</strong> says) you should get the same effect just by selecting only the red channel. How dark your skies turn out to be will depend on how blue they are: a deep blue sky, as I've found sometimes in mountains in deserts, can get very dark indeed. A cloudy gray sky will look no different.</p>

<p>Don't bother using the deep red filter on your DSLR for the reasons cited above...it will work fine with film, but not on a DSLR sensor. See the high contrast color shot below and then as adjusted with the color mixer in post processing (a lower contrast scene would have more tonality...but this example should tell you what you want to know).</p><div></div>

<p>Then the B&W using the color mixer</p><div></div>

<p>The above are important clues, particularly the use of AWB which I consider potentially misleading (but then I come from film days where you had either daylight film or tungsten); but I am trouble by the statement</p>

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<p>when I took pictures of the sky with the filter on, I got gray skies</p>

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<p>If you metered mostly sky, of course it produced a middle-gray tone because that is what the meter is supposed to do. You need to meter for an average tone on the ground, or a substitute like a gray card or your hand with an appropriate adjustment. </p>

<p>Here is what you can do. Change your "norm" color to B&W setting in your DSLR, install the red filter and shoot. Set your shutter/aperture manually and adjust till you get the effect you want (do make sure the ISO's don't fluctuate).</p>

<p>I'll try to show an example, but have to look for it.</p>

<p>Les</p>

<p>Basically, everything should be in manual....tho the WB can remain on auto.</p>

<p>Leszek has a good example where autoexposure would fool the light meter and cause the dark sky to be middle gray. Use minus exposure compensation or manual exposure. </p>

<p>I guess previous comments already referred the important aspects and reasons why you have no advantage using the red filter on the lens and I would only add that the most noticeable effect will be to cause a cal our cast affecting your image, therefore I guess with an impact on the three channels.<br>

Converting to B&W and using the channel mixer will allow you the recreate the effect you'd expect from a red filter with B&W film.<br>

Probably less effective you can shoot B&W sRGB direct from the camera and if your model allows it setting the red filter in you menu options (I guess it is a software feature after desaturating all channels to convert to and saving the B&W image).<br>

If your camera didn't have the RGB color array as the Leica Monochrom you could use the red filter and get the same effect as with a film camera.</p>

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<p>Thank you all for the replies! I took the red filter off my lens after trying many times to get a dark sky, but i was able to shoot in color and then make the skies darker my converting the picture to B&W and reducing the blues, which worked really well.<br>

<br />I also wanna try this with B&W film. Is there anything i should know in order to get dark skies with a red filter while shooting B&W film?</p>

<p><em>Is there anything i should know</em><br>

Not really, just do what you did before. The meter will take into account the filter factor (typically 8 times or 3 stops), just be aware that the resulting shutter speed/aperture combination may call for a tripod. As I said before, doing the effect digitally allows the intensity to be controlled, a red filter can easily be too much for certain subjects.</p>

<p>Thank you all very much! I am going to buy some black and white film and give it a try :)</p>

<p>When shooting at right angles to the sun, a polarizing filter helps darken the sky in both a b&w and a color photograph. This works better with a fairly long focal length lens than a wide angle.</p>