# Trapezoids and anamorphic lenses



## John Simpson (May 10, 2007)

Hi all,

Going through these house plans I may have spotted a problem: I sketched in the projector throw and discovered it's got a real downward tilt...












I know many projectors can correct for this trapezoidal skew... but what if you have an anamorphic lens stuck on the front? How exactly does that work (if at all)?

Now's the time to fix this if I need to, so yell out!


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## Anthony (Oct 5, 2006)

Wow, good question. I've never dealt with separate lenses, but since the anamorphic lens widens the picture linearly I would imagine the same keystone correction would apply, although more might be needed.

Hopefully someone who dealt with this exact problem will chime in.

Your best bet would be to have good masking around the screen, in case the "best" solution available to you still has a little extra width at the lower corners. I doubt you'd notice it on the screen, but you would definitley see the spillover if the screen is not masked well.

Good luck and let us know if/how you fix it.

Anthony


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## John Simpson (May 10, 2007)

This comforts me a little -- a diagram from a review of the JVC DLA-HD1...












It seems that these high end projectors have a huge amount of vertical lens shift, which suits me exactly.

Anthony, you could be right that an image corrected for keystoning will also be fine with an anamorphic lens, but I will continue to research that to confirm.


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## <^..^>Smokey Joe (Jun 29, 2007)

Theres a guy in aus who makes an Aussimorph lens which is reasonbly priced.

Couple things though.
It is highly likely that you will need keystone correction on to correct for that position.
For every click of keystone you might as well get a lower rezolution PJ, it's as simple as that. 
Shall I say it again...avoid positions that require keystone correction.

Try and lower the PJ or raise the screen, or maybe both.

Anamorphic lens have one issue of pin cusioning the image. A curved screen helps iliminate this issue.

Not all projectors can do anamorphic projection. If you are keen to do this, research each PJ with this in mind.


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