[0.05 lb] Given that these filters were originally intended for B&W film photography, we should be very thankful that they're still available.My use for the product is VERY specific: I have two Olympus OM-D E-M5 cameras, and also use the excellent Panasonic 7-14mm lens for my wide angle shooting. Unfortunately, the glass that Olympus uses in front of the sensor on the OM-D doesn't filter as much UV as Panasonic's. This causes fairly typical wide-angle flare to take on a very noticeable purple hue, and also causes noticeable purple reflections of bright light sources (such as bright windows in interior shots). I've had numerous shots ruined by these issues, and while I have learned to minimize and work around them, that leads to a less-than-ideal shooting experience.Thanks to some diligent work by a forum member at DPReview (Anders W), a solution was found: swap out the plastic ring on the back of the 7-14 for the similar piece from the Panasonic 8mm fisheye lens (which has an integrated filter holder - you can get the part from Panasonic) and use the Wratten 2A filter to knock out a tiny bit of purple in the visible spectrum. The result is not having to worry about purple flare or blobs in my photos any more, and very little downside for the type of photos you're likely to shoot with a wide angle lens.

[Optical Gelatin] used on the rear side of Lumix 7-14 mm. It was great.

[0.05 lb] I'm using this to reduce purple fringing with the Panasonic 14mm f/2.5 lens on the Olympus E-M5. I cut a small bit of the filter and adhered it over the rear element with double-sided tape. I've been using this solution since early May without any problems. It virtually eliminates purple fringing often seen in the image corners with this body-lens combination.

[0.05 lb] This is exactly what you would expect... a thin, gelatin filter that is extremely fragile. I wouldn't recommend any gelatin filter if it is going to be exposed to the elements... too fragile. Wratten filters are engineered with very high qc standards and are recognized as such by the fact that many scientific laboratories utilize Wratten filters for their optical equipment. If you have a need for a filter that passes or restricts specific frequencies, I would suggest purchasing a Kodak filter guidebook so you know exactly which filters will satisfy your needs, and then buying the corresponding Wratten filter. If you don't have such exacting needs, you may be better off going with a filter system such as Cokin, where they will be slightly more durable.

[Optical Gelatin] great price, great service, and fast free shipping, what more can you ask for.

[Optical Gelatin] For those of you that remember the special emulsions or films you needewd to do near infrared photography, you probably also remember that to take infrared photos, you have to have a filter that filters out the visible light. Luckily, CCD cameras are sensitive to both near infrared (light past the red spectrum) AND ultraviolet. With the Wratten 87 filter, the camera sees only what is past the visible spectrum.These filters are indispensable if you want to do IR photography.....they are available in glass as well, but the gel filters are much more affordable.Depending on what kind of camera you have, you may need a gelatin filter adapter...they are ubiquitous at any DSLR camera parts supplier.....Since I use a cheap pocket camera (eg a Canon Coolpix S9500), I simply hold the wratten filter over the lens, or construct a simple adapter....you can find references all over the web for this stuff.....The wratten filters may be cut into any shape.....NB: You can use an infrared laser as an illuminator for night photography, but of course it's spectral output must match that of the filter.....Look up Infrared and Ultraviolet photography on wikipedia for more info....have fun!