DIY Prism - 4x6 too small? - AVS Forum
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post #1 of 8 Old 05-07-2007, 09:42 PM - Thread Starter
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Hello!

I am planning to go DIY. I am getting an HD70.

I am confused about the size of the prism. I see many designs that have a 5x7 prism size....can you use a 4x6 or is that too small to project through? How to determine the size you would need? I would rather save some money on the smaller size prism if that will work.

Thanks!
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post #2 of 8 Old 05-07-2007, 10:25 PM
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It depends on the size of the beam. 4''x6'' should be fine for
most PJ's. Just put a white paper in front of the lens and measure
the size of the rectangle.

where are you planning to get the prisms?

If you are getting those plaques from massillon plaque, dont waste your money.
http://www.massillonplaque.com/produ...4&productid=85

I just got the 5''x7''. it is almost like mirror finish and gives too much reflection.
Even if this prism is coated it may not be good as they probably have polished
it like a mirror purposefully.

Even if you get it from elsewhere in US like crystal factory it might be the same
as it might come from the same glass manufacturer. These online places are
just distributors.

I have not yet seen posts from any one who bought the prisms from crystal factory
and got them coated.

I have ordered a set of prisms from Sam. They are much smaller. have to
wait and see how they perform.

The image quality will not be bad but the main drawback of the DIY
lenses is the reflection from those uncoated prisms.

Those massillonplaque prisms also put reflections right on the image.

Didnt mean to be discouraging, just my experience.
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post #3 of 8 Old 05-08-2007, 12:42 AM
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Mupi,

Like mine, Sam's prisms are coated...

Mark

Mark Techer

I love my Constant Image Height system!
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post #4 of 8 Old 05-08-2007, 05:11 PM
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Quote:
Originally Posted by CAVX View Post

Mupi,

Like mine, Sam's prisms are coated...

Mark

yep
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post #5 of 8 Old 05-15-2007, 04:53 PM - Thread Starter
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Hello again!

Since I will not be getting my HD70 until the end of June...Can someone who has one do the white paper test and let me know if I can get away with a 4x6 prism instead of a 5x7.

I am planning on having the projector around 13 feet back in a semi-light controlled room.

Thanks!
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post #6 of 8 Old 05-30-2007, 04:01 AM
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How wide is the screen?

Mark

Mark Techer

I love my Constant Image Height system!
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post #7 of 8 Old 06-30-2007, 06:30 AM - Thread Starter
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Hello!

I just picked up my HD70! I did a quick test on the wall last night with my VOOM box and a DVI to HDMI cable....awesome! Phase two will be screen design. My situation is a little different....the screen will be hidden during the day...and brought out when it is movie time. The wife does not want a big screen hanging around all the time. As soon as I figure out how far back the HD70 will be...I will start the 2.35 screen.
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post #8 of 8 Old 06-30-2007, 12:13 PM
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Quote:
Originally Posted by sillymeeee View Post

Hello!

I just picked up my HD70! I did a quick test on the wall last night with my VOOM box and a DVI to HDMI cable....awesome! Phase two will be screen design. My situation is a little different....the screen will be hidden during the day...and brought out when it is movie time. The wife does not want a big screen hanging around all the time. As soon as I figure out how far back the HD70 will be...I will start the 2.35 screen.

My wife is the exact same--whereas I consider the big movie screen to be something to show off, my wife wants it hidden away. So, we have a DIY roll-down screen (2.35:1 of course) hidden behind a valence that rolls down in front of a large window at movie time.

Registered U.S. Patent and Trademark Attorney
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