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This topic comprises 3 pages: 1 2 3
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Author
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Topic: Strong Millenium heat shield/shutter contact
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Steve Guttag
We forgot the crackers Gromit!!!
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Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 10-24-2007 05:23 PM
The shutter distance to the aperture has its ups and downs...while it is cutting a smaller cone of light, it is closer to the focal plane which makes the transition more visble...it make the Christie bow tie shutter all that much more annoying (it really is a horrible thing to sit through, in my opinion).
Mark not agreeing with the method of cutting the aperature aside...it is a fact none the less. The Simplex (conical) shutter will cut the aperture square, or more square, than either Century or Christie's bow-tie. Turn the machines over by hand and look right down the lens receiver at the aperture and see how the various shutters block and unblock the aperture...some do it better than others.
As to Kinoton...their mechanical machines have long since used a single wing largish conicalish shutter (we not so conical but angled...the AA2 shutter has a slight conicalness to it). As such, it is spinning at twice the angular velocity of a standard shutter but due to its larger radius, its linear velocity is also great there. This velocity means for a faster opening/closing off of the light as well as their ability to use a greater than 50% shutter without ghosting.
Their "E" projectors use a bow-tie shutter, angled (except for the FP75) and its velocity varies based on film speed. As such, they don't tend to look identical between a mechanical and a "E" projector. But then again, the "E" projector is notably steadier too so you are going to get a different look there.
Note, the steadiness of the projector does not affect the flicker or brightness, but it does improve image resolution as you eye will see more detail rather than using persistance of vision to morph an unsteady image into a soft appearing one.
Double shutters are another means to increase blade velocity. By adding the second shutter (counter-rotating) you double the linear velocity of the blade. This is most often used to increase light output. By making each blade smaller (less blade, but same radius), you effectively increase the "open" time so that the average light level is increased. The disadvantage to this method is that the center of the image is the last to close and first to open...as such, it will induce a hot-spot. I find they also tend to have a bit of a pulsating light to them as well.
Steve
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