I ve seen someone using a singlet element lens building a projector somewhere and the results were ok. I was wondering what contrast or haze problems I might expect because testing a slide transparency on a OHP with 1 elemente seemed ok to me.
singlets
A singlet lens has no flat-field correction, so you can focus the center, or the edges, but not both at once. You see some haze toward the edges from spherical aberration. This makes the edges blurry and lower contrast. You also see some chromatic aberration near the edges. This makes color fringes around objects. If you are using a lens with a lot of magnification, then you may also see bad barrel or pincusion distortion. This makes the edges curved in or out.
The best singlet lenses are positive meniscus or plano-convex. The right shape positive meniscus will have zero spherical aberration, but will still have the other problems. You can get a color-corrected doublet that will have little chromatic aberration. (Still has the other problems.)
I think a singlet could be good enough for a bar TV! Drunken sports fans would probably not notice the defects.
A singlet lens has no flat-field correction, so you can focus the center, or the edges, but not both at once. You see some haze toward the edges from spherical aberration. This makes the edges blurry and lower contrast. You also see some chromatic aberration near the edges. This makes color fringes around objects. If you are using a lens with a lot of magnification, then you may also see bad barrel or pincusion distortion. This makes the edges curved in or out.
The best singlet lenses are positive meniscus or plano-convex. The right shape positive meniscus will have zero spherical aberration, but will still have the other problems. You can get a color-corrected doublet that will have little chromatic aberration. (Still has the other problems.)
I think a singlet could be good enough for a bar TV! Drunken sports fans would probably not notice the defects.
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