Comments about B + W B + W 77mm #420 Glass Filter - Very Light Yellow #2E:

This filter is specifically designed to work with B&W "Film" cameras, not digital cameras.

The UV blocking level and special light yellow color are engineered to assure that each color of the visible spectrum is differentiated and assigned its own unique shade of gray.

This filter is often used for B&W "film" aerial reconnaissance photography where landscape and terrain must appear in sharp delineated relief.

I have used this filter with Kodak T-Max 100 film and my Contax G2. The result was highly detailed and contrast rich images that I have not obtained before using other filters.

The reviewer who used this filter on his "digital color" camera to photograph a UV light has not understood correctly how this filter works.

The blue color he saw coming from the UV light was in the visible range,(above 400NM).

This filter is designed to block "invisible" light in the 400NM and below range and shift the range of visible light so that all colors appear as different shades of gray on B&W film.

If the other reviewer wants to test the filter's UV blocking ability he needs to get a UV sensitive ink pen, draw on a piece of paper, shine a UV light "through the filter" at the paper and determine whether the invisible UV ink fluoresces.

If UV is being blocked then the UV sensitive ink on the test paper should remain invisible.

Please check out the samples photos I have attached. These were taken using the B+W Very Light Yellow filter #420 mounted on a Contax G2 using the Zeiss Biogon 21mm lens and Kodak T-Max 100 film.

Comments about B + W B + W 77mm #420 Glass Filter - Very Light Yellow #2E:

This may work well as a pricey lens protector, but as a UV blocking filter, I have not seen any proof.

I did several test photos of a 13W Compact Fluorescent Black Light bulb which should peak it's emission at either 350 or 370nm. Regardless of which dominant wavelength the bulb emitted, the bulk of the produced UV was well within the, as documented, attenuated band below 400nm.

I shot three photos, bulb off, bulb on no filter, bulb on with filter. My SD14 with a 28mm f1.8 EX DG recorded the lit bulb glowing a bright blue, Yes it can detect the 350 or 370nm light. With the B+W 420, I saw barely any reduction in the brightness or hue.

By contrast, I shot a fourth test, hand holding a 52mm Hoya K2 Yellow filter in front of the lens and the photographed lit bulb was nice and dark, just as it looks by eye, the only needed post processing would be to balance out the K2's yellow cast.

When I decided to order the 420, my decision was based on the B+W documentation showing it's transmission was 0% below 400nm and only climbed up for wavelengths above 400nm, hence the pale Yellow color of the filter, but the simple test above demonstrated otherwise. I doubt that a consumer grade Compact Fluorescent Black Light bulb is so bright in UV as to over whelm the filters attenuation.

Save your money and if you want true UV blocking go buy a Hoya K2.

I was considering a 415 too, but know now that it would do even less.