Playing with filters

In my Cabinet-o-Gear at work, I found a couple of old darkroom safelight filters. One of them is an amber/brown Kodak #6B filter, and the other is a green one.

According to this Kodak document, the brown 6B filter is used for blue-sensitive x-ray film with transmission bands between 560-660 nm (a fairly wide band covering green to orange) and > 740 nm (getting into the infra-red).

The green one (it's not marked but I'm guessing it could be a Kodak 7B) has a transmission band between 500-580 nm (covering most of the green band of the spectrum). It transmits the light from my green laser pointer (532 nm) pretty well, but completely blocks my red laser pointer (625-680 nm).

I thought it would be interesting to see what my camera saw through the filters. They're pretty old and a little beat up so they don't exactly have the best optical qualities but they still created some interesting photos.

The images with the green safelight filter look pretty neat

Green safelight filter

Green safelight filter

The brown filter produces a neat look

Brown safelight filter

Brown safelight filter

The green filter images turned out a lot brighter than I expected for a band pass filter. Most digital camera sensors use RGB Bayer filters to produce colour images which explains the higher than expected sensitivity with the green filter.

I'll have to see if I can clean and polish up these filters and play with them some more.