220 frame counting

[Tom Deering <tmd@xxxxxxxxxxx>]

>If you have any recorded details regarding the number of turns,

I think counting frames is the most difficult issue to resolve.

As a form of entertainment, I worked out a simple spreadsheet to 
estimate the number of turns needed to space frames equidistantly on 
a roll of 220.  This is really just a toy, since I have not actually 
tested it.  This should demonstrate how difficult the winding issue 
is.

Basically, I measured the thickness of a piece of ruined Velvia, and 
measured the diameter of a film spool.  I wound on a piece of paper 
paper backing up to the point where the film starts, to get the 
diameter right.

Then I wrote a spreadsheet to add up the number of turns to space the 
film correctly on the film.  The number of turns decreases as you 
shoot because the diameter of the spool increases as you wind film 
onto it.

shot   diameter    turns
1      13.1 mm     5.9
2      13.8 mm     5.6
3      14.5 mm     5.3
4      15.1 mm     5.1
5      15.8 mm     4.9
6      16.4 mm     4.8
7      16.9 mm     4.6
8      17.5 mm     4.5
9      18.0 mm     4.3
10     18.6 mm     4.2
11     19.1 mm     4.1
12     19.6 mm

So you can see that you would have to keep pretty good track of the 
number of turns  per frame(not so hard) and the number of frames shot 
(much harder, for me at least).

However, seeing that the first frame required almost exactly six 
turns, I wondered how many frames I would lose if I just wound six 
times for each frame.  I modified the spreadsheet and discovered I 
would lose two pairs.  By the end of the roll, there would be 2 
inches between shots, but that's the price of easy 220 frame 
measurement.  Ten pairs to a roll of 220 doesn't sound too bad.

(I've been holed up for the past few weeks working on an assignment. 
I'm just reading these messages now.  No wisecracks regarding the 
habit of writing spreadsheets for entertainment, please.)

Tom
-- -- --
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