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I recently acquired a small blue/violet circular viewing filter.
I understand the principles with the amber style of filter where the filter is flicked in and out of view and a monochrome "impression" of the scene is created.
This blue filter seems similar to the amber one but I was wondering if anyone on list has one of the blue type and how you use it to best advantange?
The blue filters are for use with color transparencies. They will render the shadows closer to what they will be in the image, usually much darker, when a scene is viewed thru them. This is due to the films lack of sensitivity to lower tones. I have the one made by Zone VI and it is pretty good in its function. On occasion I would take the picture anyway even if the viewer said the shadows would be black, The viewer was right and the image was a waste of film.
Harrison & Harrison did make a blue panchromatic viewing filter. They are used in the same manner as the darker brownish ones. I primarily use min in very low light and indoors fo ambient lighting.
Blue is the right color for a BW viewing filter. If you take a conventional spectral film response (HP5, Tri-x, etc.) and multiply by the human eye response, you get a highly blue response. Viewing a scene through the blue filter should give you the most accurate visualization of what BW film will render. I have no idea why amber, brown, or the wratten 90 came to popularity.
I would tape a rectangle to the viewing filter such that it mimics the aspect ratio of your camera. You will soon learn when framing a scene, which lens to use based on how far away the filter is from your eye.
As you said, the filter gives you a monochromatic view. It should also make you keenly aware of the brightest and dimmest areas of your scene. When you suddenly place the filter before your eye, the brightest areas will reveal their differences and allow you to see them within your eye's dynamic range: better evaluation of highlights. The shadows will drop into blackness (blueness) and make you aware of the darkest area of the scene and help you meter and place shadows. Any dark filter is good for this.
Good luck.
I do not understand the statement that "Blue is the right color for a BW viewing filter". Blue filters are the only color filter that will reduce contrast. It does it by raising the tonal values of shadow which are mostly blue light. Blue filters are frequently used to mimic the orthographic films of old usng the panchromatic films of today. So I don't see how a blue filter will give an acurate representation of how a scene will look in B&W.
Alan,
The blue viewing filter is for you and not for use on your camera. It is to reduce the color constast of your eye and let your eye see a film response. It doesn't matter what the blue would do with BW film.
If the object is for your eye to see what the BW film sees, then the filter you need to do this is the product of the spectral sensitivity of your eye (which is very peaky in the green with little response in the red and blue) and the spectral sensitivity of the BW film you use. For me, I use HP5+, which is sensitive in the blues and greens. It is similar to most BW films, except IR films and to some degree T-grain films which may have a little more red -- or not. Anyway, you can understand that most of the action is in the blue-green for film. Understand that your eye does not see blue (violet, indigo, blue) very well -- only 10 to 20% as well as green. Therefore, you need an aid, a filter, to force your eye to see what the film sees and what the film sees is blue-green. To force the relative relationship of the blue and green to your eye that only sees green 'well', the filter needs to be a deep blue.
Photopic vision curve link:
http://hyperphysics.phy-astr.gsu.edu...bright.html#c2