At 05:20 PM 7/2/03, Bill Stanke wrote:
Help me out here. I'm trying to wrap what's left of my brain around the
concept of infrared flash. Is there visible light also, or is it all
IR? When do you use IR flash? Any experience with this?
It's used with IR film. It can also be used to trigger slaves on studio
lights. Indeed, I have a small electronic IR flash that fits into the hot
shoe. It does emit a small red glow when it goes off, but it's very red
and very dim. Here's the kicker . . . optical slaves are very sensitive to
not only visible light, but IR as well, and I use the small IR flash with
the standard optical slaves built into my monolights. Alas, IR triggering
does not work worth a hoot on-location in a church for wedding portraits,
but it works extremely well in my makeshift studio at home.
You can make your own IR flash from a standard electronic flash very
easily. Simply cover the flash tube cover with a piece of completely
exposed and developed slide film (should appear to be completely
black). These can be had easily by shooting slide film and keeping the
piece(s) of leader they return with the slides. Slide film, after
developing is specifically designed to be very nearly completely
transparent to IR, without regard to the density of the visible light image
on the slide. Why? If slides didn't allow transmission of nearly 1000f
IR, they would melt and fry in a slide projector.
-- John
The author later mentions a 85 mm f/3.5 Quartz-Takumar for UV
photography. Double huh?
Yes . . . although I thought only Nikon made quartz lenses for UV
photography. Glass attenuates UV considerably. First I've heard about a
Pentax quartz lens. Most who do UV phtography typically use prime lenses
with as few/thin glass elements as possible. If that isn't good enough,
there are the quartz lenses, but they cost big bucks. Quartz transmits UV
much, much, much better than glass.
-- John
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|