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Topic: Sankor Anamorphic lens
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Joerg Polzfusz
Jedi Master Film Handler
Posts: 815
From: Berlin, Germany, Europe, Earth, Solar System
Registered: Apr 2006
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posted July 28, 2006 03:36 AM
quote: So, Joerg, I bet you could easily place your scope lens further away from the T610, possibly far enough to still allow you easy access to the frame advance knob if need be.
Yes, it works. But it's a very close thing - if I move the scope lens a single millimeter close to the projector, it'll touch that knob. If I move it more than 5mm further away, I can't focus anymore and get vignetting.
quote: I've never seen anyone use a 35mm scope lens with a super-8 camera...
I've spoken to some other amateur filmmakers. They agree that the rectimascope gives a very sharp projected image. But according to them using it for filming is a waste of filmstock since the image will allways be out of focus. And due to its lengths, you'll run into the same vignetting problems as when using smaler anamorphot. (Not to mention that e.g. a Kowa wheights much, much less!) I don't know if this applies to other 35mm-projection-anamorphots from Schneider/Isco/Möller/... though.
Jörg
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John Whittle
Jedi Master Film Handler
Posts: 791
From: Northridge, CA USA
Registered: Jun 2003
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posted July 31, 2006 10:42 AM
quote: What is an 'astigmatism'? (Sounds like some sort of illness to me, actually)
It is an eye condition as well (I know, I have it and have it corrected in my glasses).
What it means is the scope lens only converges in the horizontal. To properly focus a scope lens you would would an SMPTE target with the scope lens off and get good overall focus of the chart. Then you put the scope lens in place and you'll notice as you "focus" that the vertical lines will be the ones that become wider or narrow (as it gets "in to focus").
If the front and back elements are not perfectly aligned, then it can never get into razor sharp focus and the first thing you notice is a drop in contast, then an overall softness to the image.
With the proper tools, you can align the lens. But I think those days, those technicians and those tools are long gone for the small lenses. In any event it would cost five to ten times what a used lens sells for to fix one.
The short take, that's why I always recommend you try a lens in your screening room before committing to purchase--I've had my share of soft lenses and have actually corrected a couple.
For the record, the further apart the front and back scope elements are, the more distant the focus. The closer together the shorter the focus distance. This will vary with lens formula somewhat but it's one of the reasons that theatre scope lenses won't focus at a twenty foot throw.
John
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