IR flash & NV notes

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

Hi gang,

While digging through my pile of IR documents and books, I found some 
more flash related comments:

Extracted from "Fotografieren auf andere Wellenlaenge", by Rudolf 
Hillebrand.

- He mentiones that flash has the same spectral output as photo
lamps; ie relatively twice the output in IR as daylight. A bit
confusing IMO, since the color temperature of flash (5000-5500K) is
almost identical to daylight, not to photo flood lights (3200K).
Maybe a flash bulb cannot be considered a true black body light
source afterall. 
He also states that Nitrophot lights are recommended for IR studio
work [does anyone know what color temperature those have?]. Halogen
(3200K) bulbs are also a good alternative, because of the higher
light output in general, 1000W is common.

- the following manufacturers make/made IR covers for their flashes:
  -Metz (think only for the 60, combined with a fresnel/tele cover)
  -Sunpak for the 622 Pro
  -Nikon made a special version of the SB-14, the SB-140; one year after 
the release of the UV-Nikkor f4.0/105mm. This SB-140 came with three 
covers, the SW-5V for visible output, SW-5UV for UV output 
(300-400nm, GN 16), and SW-5IR for IR output (750-1100nm, GN 22).
Assuming that the '140' stands for the visible GN in feet, the GN in 
meter was 43. So for *that* flash the IR GN was halved....

BTW, in line of unobtrusive animal photography this chapter is
followed by a chapter on night-vision scopes. I knew I read about
the Zeiss N-Mirotar photo scope before, but only after rereading I
discover that this contraption was made for Yashica/Kyocera, with a 
Contax/Yashica mount. Anyone ever seen this beast? 
He also mentiones the fact that Pentax had such a NV photo-scope in
its program, for a very brief period. Can anyone remember that? (I
am probably too young to know all this....8-))


Extracted from "Moderne Infrarot- und UV-Fotografie", by Guenter 
Spitzing:

- #87C gel filters show heat defects after 100 bursts or so
- GN's for flash covered with Schott RG 780 or #87C:
  -disposable flash blocks: HIE 20, IE 14 
  -AG3B/XMlb: HIE 25, IE 18
   (I assume this is a flash, beats me what brand/model
  -general flash with GN 26/28: HIE 32(?), IE 18

- ISO setting for EOS camera (pay attention Joe!):
  -'flash' covered with RG780/#87C: HIE 200/24, IE 100/21
   (I guess they mean EOS flash here)
  -Sunpak 622 IR head: HIE 400/27(!), IE 80/19

- the book also mentions that owls are highly insensitive to IR
light, in contrast to almost any other bird. Fish in general also.
Maybe a bio expert amoung us can add a few more samples? 

- for maximum light output, one can also consider using a UV/short
pass filter, like the Wratten #18B or Schott UG1 or UG11. Almost all
UV pass filters also transmit IR, so given the UV sensitivity of both
HIE and IE, one can use the invisible UV *and* IR spectrum with these
filters. 

That's all for now!....:-))


--
Bye,

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The difference 
between men and boys
is the price of their toys

<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]

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Topic No. 13