oxberry optical printer riddle

From: amanda christie (email suppressed)
Date: Fri Jul 14 2006 - 00:25:05 PDT

greetings fellow frameworkers

(i've been avoiding email for a while, and there were
over 1500 frameworks messages when i logged on
today... took a few hours to get through, but i'm
back... bleary eyed, but finally caught up, amused,
and inspired)

we have a dillemma with our oxberry 16/35 optical
printer at the cineworks independent filmmakers
society here in vancouver.

this dillemma has stumped myself, and all of the other
filmmakers and technicians who have looked at it.

perhaps some of you may find this to be a fun riddle
or brain teaser. set your sudoku aside for a spell
and try this one on for size.

if i had money, i would offer a prize to anyone who
can solve this riddle. but since i don't have money,
i will send a huge huzzah to anyone who solves the
riddle...and i'll buy the person a drink if i ever
meet them in the flesh.

here it is:

- the problem does not occur when shooting 16mm.
- when the camera is set up for 35mm, there are
occasional streaks of light across seemingly random
- this "flash" or "streak" appears in the top 1/3 of
the frame, and travels on a slight diagonal from one
edge to the other (sprockets, edgecode et al), leaving
normally exposed image above and below
 - this streak is about 2mm on one side and expands to
3 or 4 mm on the other side
- this streak is not in sharp focus
- upon further inspections it "seems" that the streak
occurs in multiples of 4 frames. usually every 12
frames, but sometimes fainter streaks appear every 4
or 8 f rames, and sometimes dozens of feet can go by
with no streaks, and then they will appear again, but
always in multiples of 4 (or so i think i recall...
it's been happening for over a year, and it's been a
year since i inspected someone else's film).

hmmmm... what else....

ah yes.

- if you work with all of the lights out in the room,
in total darkness, you don't get these streaks.

and yet!

- we have tested the camera and the magazine for light
leaks and they're fine. totally light tight.

- the bellows however, do have light leaks, but HOW
would light get past the shutter anyway.


MY theory is that it has something to do with the
shutter. i think it may not always be stopping in the
right place or at the right opening size. but when i
remove the gate and run the shutter over and over and
over again, it stops consistently even in the same

and even if it was the shutter, i would suspect taht
the full top third of the frame would be fogged. but
this is not the case. the streak crosses the frame,
leaving normally exposed image above and beneath it.

there are 7 or 8 of us here, technicians and
filmmakers who can't figure this out. only one of
them agrees with me that it might be a shutter issue.
all of us are in agreement, that this should not even
be possible. we couldn't make a camera do this if we
wanted to.

so far, we've only analyzed this problem on people's
actual (unfortunate) footage. come late
august/september, i will be running actual full on
tests of various scenarios.

in the meantime, has anyone had this happen to them
does anyone have any ideas as to what it might be?

my deepest respect to anyone who even attempts to
solve the riddle,
and a free drink if i ever meet you in person.

practicing mental gymnastics,

amanda dawn christie
vancouver, bc, canada

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