View Full Version : Filter for High Altitude

Douglasa A. Benson
21-Aug-2000, 16:56
Greetings, Is there a reason to prefer a standard UV filter over a Skykight or "Strong UV" ala Schneider 415 for shooting in high elevations? I will be exposing Velvia as well as black and white.



Bob Salomon
21-Aug-2000, 17:42
For high elevations you need stronger skylight filters for color like a KR 3, KR 6 or KR9

For black and white you need stronger UV filters and they are too yellow for color.

John Lehman
21-Aug-2000, 18:08
As one who does alot of aerial mountain photography (including large format), the answer is yes, even with print film. There are four problems you face:

1. With lots of UV around, you can get out of focus ghost images, since your lens is probably not corrected for it. A regular 1A UV filter solves this.

2. Film responds much more to violet and UV than eyes or meters, and so you tend to get over-exposure. A 1A filter will not help this much; a stronger filter (e.g. a HF-3/2B, etc) with TTL metering will. Since each meter varies, experience helps.

3. Because the film (either color or BW) is over-sensitive to UV, violet, and blue, you tend to get a bluish color cast. A 1A filter is not strong enough to help this; a color conversion filter or a stronger UV filter helps.

4. Aerial haze is worst at short wavelengths.

Kodak recommends for aerial use a minimum of a #12 filter for black and white, and an HF-3/2B for color. A color correction filter of about 20R or a color conversion filter of 3-4 decamirads (e.g. about an 81C) will also work if it also filters UV (Kodak's wratten 81B/C for example do not).

Ideally you would like something like a 2A or 2B which have a very sharp cutoff right about the beginning of visible light (around 400). I have not used the B&H/Schneider strong UV filter, but you ought to be able to find performance curves for it.

Bob Salomon
22-Aug-2000, 06:27
In case you wonder what brand filters are used in the Space Shuttle it's Heliopan and that is as high an altitude you can get with film based cameras.

William Marderness
22-Aug-2000, 13:44
Instead of spending extra on the speical-order B+W 415 for black and white, why not buy a B+W 021 light yellow filter or use an everyday #8 medium yellow? I don't use a UV filter for B+W, since I opt for one of these instead.

For color, use a skylight or 81A/B. These do not filter out as much UV as a UV filter does, but they will give better color rendition.