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I have purchased a couple of prisms from surplus shed and originally had decided to do horizontal stretching but have read that vertical compression has fewer issues and produces a better image. Is this true? Also are there any good build threads that have used a vertical compression? Can it be done with prisms still? Thanks so much for any help/info!
 

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Quote:
Originally Posted by ojuicy /forum/post/20891342


I have purchased a couple of prisms from surplus shed and originally had decided to do horizontal stretching but have read that vertical compression has fewer issues and produces a better image. Is this true? Also are there any good build threads that have used a vertical compression? Can it be done with prisms still? Thanks so much for any help/info!

VC lenses are still prism based. Panamorph has stated they prefer VC over HS lenses. Maybe barrel distortion is less offensive to pincushion. I believe it may have more to do with the fact that VC lenses are more useful with projector with limited throw ratios like 1.0-1.2 and at much longer throws, which, in and of itself, improves distortions.
 

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Quote:
Originally Posted by ojuicy /forum/post/20891342


I have purchased a couple of prisms from surplus shed and originally had decided to do horizontal stretching but have read that vertical compression has fewer issues and produces a better image. Is this true? Also are there any good build threads that have used a vertical compression? Can it be done with prisms still? Thanks so much for any help/info!

The issue that comes to mind with using these prisms is that they are only about 75mm (3") high. When you turn these on their side to form a VC, there is now just 75mm (3") of width. So you will need a really long throw or you will get vignetting.


Yes, a VC need only have 2 singlet prisms where a HE really needs 2 Doublets plus a correction lens.


VCs exhibit barrel distortion, so a flat screen is best here.
 
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