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Hello! I wanted to try some Maco Cube 400 35mm film
since it is panchromatic and its sensitivity extends to 720 nm. I used my
Kodak gray scale under a 5000K fluorescent bulb and obtained normal exposures
at 1/8 second at f4. I then used my ND 10,000 filter and exposed the gray
scale at f4 for 20min 50sec. I developed the film to an ISO of 400
according the manufacturer’s recommendations using SuperGrain developer. The
film appears to have about 2 2/3 stop loss over this exposure period. For interest sake, I then repeated this
test using my Lumicon H-alpha filter. I obtained a normal exposure at 1/8
second at f1.8. I exposed the gray scale for 20min 50 sec using the
10,000 ND filter over the H-alpha filter at f1.8 and developed the negatives to
an ISO of 6400 in accordance with the manufacturer’s recommendations.
The film again appeared to have a 2 2/3 stop loss over this time using the
H-alpha filter. The film is sensitive the H-alpha, but
has a speed stop loss equivalent to llford SX-200. If this film can be
pushed to such a high level then the 2 2/3 stop loss may be inconsequential if
the grain is tolerable. Given the upcoming demise of Tech Pan, one
possible use of this film would be to use 4x5 TMax film (or other H-alpha
insensitive B+W film) to obtain tri-color negatives (or to use color slides or
negatives for the color work) and use a sheet of Maco Cube developed at 6400
for the H-alpha channel. 35mm film may be able to be used instead of the
sheet film since the grain might not be noticeable in the final processed print
since the grain would be isolated to only the H-alpha channel. However, 4x5
sheet film developed at 6400 might have minimal grain in any case. Best regards. Mike --- |
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