Re: Question on film

[PeteScherm@xxxxxxx]

I have just been reading my father's 1945 copy of  "Data Book on 
Black-and-White Kodak Films", which includes information on the "old", 
low-speed IR once offered by Kodak.  The Film Exposure Index had a Tungsten 
rating of 8 (no daylight rating).  The film (based on the difficult-to-read 
nanometer-scale photograph) was slightly less sensitive at the upper end.  It 
appears to die-off around 870, but they advise a #87 filter can be used.  
Interestingly, the sensitometric curves show a horizontal line at the base, 
at about 0.3 density, identified as "Density of antihalation base".  This 
apparently explains  the existence for the following, final item on the data 
page:

ROLLS AVAILABLE:  Bantam - IR828 roll.  35-mm. - IR135 (36 exposures), and 
No. 401 (50 ft.) roll.  Roll Films (6 exposures) - IR116, IR616, IR120, 
IR620, IR127.

My father shot his first roll of this film in 1941 with a Kodak Duo-620 
(equiv. to a 645 format) and continued using the film until about 1950 
(although the latter rolls could have been purchased at an earlier time.  I 
have all of the negatives and they do seem to show the lack of halation and 
"dreaminess" of current HIE.  

Pete Schermerhorn, in the glorious Berkshire hills of western Massachusetts
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