Minox 8x11 Frame Spacing
In 97, I happend to shoot a roll of 15 exp film with my Minox B, and the spacing came out much wider than usually, I asked a few Minox veterans, but no one had the answer.
finally I found out it is due to the fact the 15 exp cassette is using a different kind of spool-- a thicker spool. The spool in 36 exp film is about 10mm, the ones in 15 exp is about 12 mm.
Minox B, as well as Minox II/III/IIIs, uses no sproket holes to drive the film, instead it uses the turning of take up spool to pull the film through.
At the beginning of a roll, the diameter of film rolled on the spool is small, as more and more pictures being taken, the diameter becomes bigger and bigger; to keep the spacing equal, Minox uses a compensation mechanism, such that at the beginning, it turns a larger angle, and as the film roll getting bigger, the turn angle must be smaller.
If 36 exp film and 15 exp film all use the same 10mm spool, then both of them must be loaded at 0 position of Minox B(or A ).
But since 15 exp film uses a bigger diameter spool to begin with, if it is loaded at 0 as I did, than wide spacing resulted, because at 0 position, the rotation angle of spool is largest. There fore, if you want regular spacing, you must move the loading point to 20.
Why ? Current 15 exp film is made for down counting Minox TLX/EC/ECX, for which the loading point is at #15. count down to zero. If we map TLX counter to Minox B counter,
#15 of TLX = 20 of Minox B; when TLX count down from 15 to 0, Minox B meter counting up from 21 to 36.
-- martin tai (martin.tai@capcanada.com), January 01, 1999.