This is an argon-filled bulb from the 1970's. The leaves, upon which you can still see small traces of green, were made to glow that color by coating them with barium; the purple is the normal emission for stimulated argon. The rest of the bulb appears black because it became coated with material emitted from the internal electrode structure over hundreds of hours of operation; when new, the bulb was clear.

These bulbs had very short lifetimes; about 400 hours. This one, found in a box of old stuff I was looking through, has become almost too dim to be sure it's on to the naked eye. To the 6D at 1000 ISO, however... well, as you see.

I found that some of these, still in new condition if you believe the auctions, are still available via EBay, but quite expensively.

Cruder versions from China are presently about $5.00 each, both on EBay and on Amazon. Here's one

EOS 6D, EF 50 mm ƒ/1.4, ES 71II hood: 8 seconds, ƒ/8, ISO 1000, mini-tripod. Emitted light.

#art

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