70mm

[Jim Henderson <74023.723@xxxxxxxxxxxxxx>]

I have been using 70mm Kodak Infrared Aerographic Film 2424 since 1987 in a
Mamiya RB 67 70mm back using Kodak 70mm metal cassettes.

The film is available in 70mm x 150 ft (45.7 m)  with 35mm perforation (Sp 494)
as Cat. No. 169 0841 from any Professional Kodak Dealer (have them look in the
Aerial film section of their ordering book).  No information is available from
Kodak's Web site on this film.

I have been loading HIE directly into the Kodak metal cassettes in TOTAL
darkness (turn off all fluorescent lights at least 2-minutes prior to loading)
directly off the metal spool onto which it is wound.  I have not found that you
need any bulk loader.  I fashioned a dowl rod into a tapered end which fits
snuggly into the plastic end of the takeup spool inside the 70mm cassette.  I
placed a finishing nail 90-degrees to the axis of the dowl rod so I could
"crank" film onto the takeup spool inside the cassette.  Turning the crank
approximately 60 turns places about 65 exposures inside the cassette.

I rate the film speed at ISO 200 (daylight) with a Wratten 25 (red) filter over
the camera lens using off-camera metering (without the red filter over the
meter).  Using an 87C filter lowers the ISO by a factor of 2.5

I process the film in TMAX-RS developer diluted straight from the concentrate.
I mix parts A & B together into the original container.  Dilute the concentrate
1:9 using deionized water to minimize pinholes.  Develop for 8-minutes at 70F
for a cold-light head enlarger with variable contrast paper.  I use a 70mm
Kinderman reel and tank.

The major problems surrounding use of this format are those of incorrectly
closing the 70mm cassette, which allows fogging to occcur in camera.  The other
area of concern is the felt light trap on the film back.  Replace every 3 years
if you use the back heavily, as I do.  If you purchase a used back, inspect the
felt lining for signs of deterioration.  It will cost about US$125 to replace
the felt, but this is insignificant since the new backs are up around US$1.050.

I have imaged everything from archaeological artifacts to body portraits and
have found the option of having 65 exposures available without changing backs or
reloading film out in the field very nice, indeed!

Jim Henderson
Applied Scientific Photography
email:  hendersonj@xxxxxxxxxxxxxxx


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Topic No. 10