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View Full Version : So ... Filters ....



SteveKarr
28-Dec-2009, 10:11
Ok a filter question for those who know...

If we shoot say outside with yellow, orange & red filters to bump contrast by suppressing the blue in the shadows (in normal film, not X Ray or some limited spectrum stuff) will it work more as an ND on overcast days where there is no "Hard" warmer light to use as a key. If it squishes the blue light and that's all there is .... well...

Thanks in Advance!
Steve

Joanna Carter
28-Dec-2009, 10:47
If we shoot say outside with yellow, orange & red filters to bump contrast by suppressing the blue in the shadows (in normal film, not X Ray or some limited spectrum stuff) will it work more as an ND on overcast days where there is no "Hard" warmer light to use as a key. If it squishes the blue light and that's all there is .... well...
The idea of using filters such as red and orange, is to make anything that reflects the opposite colour of the spectrum appear darker, whilst making things that reflect their own colour appear lighter.

So, a red filter will tend to make a blue sky appear very dark, whilst making red brickwork appear quite light, to the point where it may be difficult to distinguish the bricks from the mortar between them.

Ther is not much point in trying to use red/orange filters to increase contrast on an overcast day; if there is nothing blue/green in the picture, nothing will be made darker, it will simply increase the necessary exposure. Filters don't "squish" light, they only alter the relative gray level of certain coloured objects.

Larry Gebhardt
28-Dec-2009, 12:15
Yes, it will work as a ND if all the light is of one color. However, even with skylight, that is not the case for most photos. The green foliage will have different amounts of red light reflected than the gray rocks, so there will be some tone shifting going on.