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Here we have a
garden variety (well...not quite, I imagine you'd be quite surprised if
you found one of these in your garden...you know what I mean though!)
F8T5 fluorescent tube. Who made it I have no idea, as there is no
makers name printed on it anywhere, nor was there any packaging
supplied with it.
One of my long standing interests in lighting terms has been
fluorescent lamps in unusual colours. While blue isn't by any
means unusual, it's different enough to your normal various shades of
white that it interests me.
The phosphor on this one relative to your normal "white" tube seems to
have a lot less in the way of red emission, with a nearly continuous
output from mid green through to deep blue. This results in quite
a pale blue colour to the light. Somewhat less green though than
the lights you tend to see used to attract insects though, despite the
similarity in the photos below. There is sufficient deep blue
output from this light to cause considerable fluorescence from many
typical fluorescent coloured objects.
This particular lamp attracted my attention initially as well due to
the end caps seeming to be a couple of mm smaller than on most of the
other F8 tubes I have - being quite a bit narrower than the tube
itself. This and the fact that the phosphor doesn't actually go
all the way to the cap means that you can see into the tube a little at
each end, the close-up shown below lets you see the bright reflection
from the phosphor internally.
The one downside of the particular phosphor mix is that it appears to
have a far shorter persistence (time taken to stop glowing) than the
normal triphosphor mix. This means that when operated on a
conventional magnetic ballast, it flickers quite a lot more visibly
than normal white lamps.
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