Re: DAYLIGHT, LOADABLE, Kodak, B&W, Infrared, Film, for, sale, $8.45/roll

["Rolland Elliott" <rolland_elliott@xxxxxxxxxxx>]

Andrew your failure was probably the result of one or more of the following 
condtions.

1.  You were using casettes with transparent IR felts. Almost all bulk 
loadable film casettes' felts leak IR light. Only a couple of manufacturers 
use IR opaque felt material and even then they do not consistently use the 
material. If you look at the casette with an IR camcorder it will either 
show up as white or black. Never use the white casettes; they leak IR light 
tremendously. Would you buy color film casettes that had white felt material 
instead of black? Hopefully your answer is NO.  However this is effectively 
what Kodak is selling you when you buy their preloaded IR film. You just 
can't see it because you can't see IR light. Under visible light the felt 
appears black, but under IR illumination the felt is a bright white.

2.  Just because you exposed and developed B&W film so that it has an  
opaque emulsion COATING to IR light DOES NOT mean that the film base will 
NOT pipe light through to the inside of the casette. If you paint the 
outside of a fiberoptic cable black it will still transmit light (or pipe 
the light) from one end of the other.  In fact if you paint the outside of a 
fiberoptic cable with a reflective coating it will actually increase the 
light transmission or piping.

One must use a film base who's index of refraction is such that it doesn't 
pipe light to the inside of the casette.  OR use a material such as black 
paper that doesn't really have a index of refraction.
HIE 's estar base pipes light very well. The entire 12" length of film I had 
in the casette was exposed when I did not tape on a leader to the film.  For 
those of you rusty on high school physics, Fiber optics and film is able to 
pipe light because the index of refraction of the material is such that the 
light is continually reflected off the in sides of the material.  If the 
index of refraction is too high (or maybe it's too low, I'm rusty too) then 
the light will pass through the material instead of being reflected 
internally.

The index of refraction is a physical property of the material and the 
ability of a material to pipe light is somewhat independent of what  paint 
or emulsion you coat the ouside of the material with.  Unexposed Velvia 
works fine, I'm going to try some Ektachrome Dupe film unexposed next. I 
have a whole stock pile of that stuff I got for $6 per 100 feet.

Peace, Rolland

Andrew wrote:
"I had tried this approach (as posted on this list more than a year ago)  
but
could not totally prevent fogging of the film even if the leader (of exposed
and developed B&W film) was 18 inches long. It seems that there was
considerable leakage past the felt trap ... more than just light piping, and
possibly even from the top and bottom of the casette."

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************