One thing to mention is most glass filters are actually of a 'glass-filter-glass' sandwich construction, ..
I don't know of any current manufacturer of filters except for Tiffen using that construction.
It makes sense when a spectral curve is achievable with dyes in gelatin (or plastic or whatever Tiffen packs in there), but not achievable with in colored glass. Which filters are those? On the other hand some spectral curves are only achievable in glass. Which filters are those?
Solid glass filters are far superior optically. For one thing, Tiffen filters lack anti-reflection coating. Tiffen offers this gibberish justification:
Q: Do multi-coated filters offer a benefit over Tiffen non-coated filters? A: Only to the extent that they emit about 1/10th of an f:stop more light, which is almost immeasurable. Coated filters do cut down lens flare. This can also be done just by using a lens shade. Furthermore, many multi-coated filters on the market are not coated 8-12 times as found in lenses, but usually about two times, and sometimes not even on both sides of the filter! Properly coated lenses minimize or eliminate lens flare with or without coated filters.
They concede that coated filters can cut down lens flare but reply that the lens shade can also do it. This misses the point that coated filter + lens shade assures lower flare than uncoated filter + lens shade. Their final sentence commits the same fallacy. Work it out. The uncoated Tiffen filters have about 4.2% reflectance on both sides. These two reflectors can exceed the total of all the reflective surfaces within a complex lens. Lens flare and glosts is caused by one surface somewhere in the lens reflecting the light back toward the scene and then another surface forward of that surface sending it back toward the film. The Tiffen front surface can play the second part, and the Tiffen rear surface can play either the first or second part in a flare contributing scenario. With a high quality lens having 10 air-to-glass surfaces, all multicoated to have 0.4% reflectance, adding the Tiffen filter will multiply the lens flare 8×. With a cheapo lens having 6 air-to-glass surfaces, all MgF2 coated to have 2% reflectance, adding the Tiffen filter will multiply the lens flare 3×. This quick analysis has ignored diffuse reflections within the lens assembly.
Here is one independent tester who, whether they realized it or not, failed the Tiffen filter on account of its being uncoated: http://www.lenstip.c...en_72mm_UV.html
Uncoated filters suit macho film crews who can wipe 'em on their sleeves.
In general, thicker optical glass can be ground and polished flatter than thinner optical glass. So unless the Tiffen filters are twice as thick (and heavy) as competitor's filters, or ground and polished with special effort, they are of inferior optical surface quality to the competitors. This can be measured with an interferometer. Someone should.
Tiffen's uncoated, sandwich type filters have a cult following, especially by US cinematographers. Why?
Edited by Dennis Couzin, 18 February 2015 - 02:03 AM.