Originally Posted by
John Layton
How about a circular race ball bearing mechanism surrounding the lens? The "fan" itself (laser cut from thin aluminum and black anodized) would consist of two or three blades...wider in the middle and tapering to very thin where they intersect the edge of the race at three points. The blades would obviously need to be curved downwards towards the edges as the race itself would need to be quite low-profile, so as not to interfere with the image field.
The outside of the race could be cut with gear teeth (or a ring gear attached to the outer circumference)...which are driven by a spring wound mechanism which would be cocked and fired like a shutter. Could utilize something like a slow speed mechanism (could use an existing one?) to keep the fan speed constant. Or perhaps that outer race gear could be incorporated into such a mechanism. If you watch one of these closely in action (remove one from a copal shutter and work it around)...you might see what I'm saying. Would be great I think!
Oh...and you could also incorporate something like a self-timing mechanism for much longer exposure intervals.
Seems like you'd have enough room on the flat of that plate surrounding the lens for something like this. What do you think?
At any rate...its so very exciting to see that you are re-creating such a fascinating lens! (I want one!) Good luck!
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