Why Curved, If Anamorphic, for 720p projector? - Page 2 - AVS Forum
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post #31 of 42 Old 10-15-2010, 11:03 PM
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The projector/lens combo can be mounted inverted or from a self. I've inverted my projector as I found I could see a "hot spot" (direct reflection of the lamp) when shelf mounted.

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post #32 of 42 Old 10-16-2010, 04:31 AM
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Thank you, CAVX! Your information (here and elsewhere) has been a huge help

I'm considering the da-lite high power screen for use with my JVC HD250 w/ a-lens and the HP screen (they call it a "retro-reflective" screen) requires head height projection, thus, I need to shelf mount. That solves my question; thanks again.
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post #33 of 42 Old 11-06-2010, 02:25 PM - Thread Starter
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Well i'm planning to buy epson 8350 next year.

What do you think about this:
- Making curved screen 30'
- Using anamorphic ready option on the unit to hide black bars
- and buy Geometric Correction Software like nthusim, pixelwarp or univisual warpalizer instead anamorphic lens....
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post #34 of 42 Old 11-06-2010, 02:58 PM
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Quote:
Originally Posted by Vao View Post

Well i'm planning to buy epson 8350 next year.

What do you think about this:
- Making curved screen 30'
- Using anamorphic ready option on the unit to hide black bars
- and buy Geometric Correction Software like nthusim, pixelwarp or univisual warpalizer instead anamorphic lens....

Two things:

1. Curved screens are for correcting pincushion from Anamorphic Lenses. If you don't use an A-Lens, DON'T use a curved screen as you'll be correcting for a problem that is not there and as a result, actually adding a problem - IE barreling to the image.

2. The end result of using that software with VS will the same as electronic zooming the image. Yes, you rid the black bars and you also then lose 33% off the width as your projectors panel is 1.78:1, not 2.37:1. So basically, your centre cropping the Scope image to fill your projectors panel and you'd not fill a Scope screen anyway as the image is now 16:9.

Does that make sense.

Mark Techer

I love my Constant Image Height system!
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post #35 of 42 Old 11-09-2010, 08:43 AM - Thread Starter
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Agrhh not that easy then... I'm trying to find the easiest way to do curved screen including all necessary stuff with it but now i realize that I even don't now if I could do just a flat one...

The people are buying lens for about 2000$ and more but there are some for 130$ only. Is this for 130$ will doing the same job like these for 2000$? Is the difference is so huge? Does it worth it? I'm afraid that if I buy these cheap lens I will lose from quality of the picture. Don't see a reason to buy a native 1080p projector when I'll lose the most important thing on it - the quality. I can't realize why if there is nothing wrong with these surplus lens the people are buying lense for even 5000$...and so on...

I want to do a CIH screen. I just need to choose flat or curved depending of what I can do.

My major mission is:
1080p projector
-CIH screen
-first way - flat screen
- second way - curved screen
If i go to flat screen i need to hide the black bars somehow. If i buy anamorphic lens to do so why I don't go to curved screen...

its a mess i know...sorry about it.
Alex
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post #36 of 42 Old 11-09-2010, 02:43 PM
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Quote:
Originally Posted by Vao View Post

Is this for 130$ will doing the same job like these for 2000$?

You get what you pay for. Both can provide a 1.33x horizontal magnification.

Quote:


Is the difference is so huge?

Yes

Quote:


Does it worth it?

My first lens was a pair of water prisms that cost me about $80. From there I just kept going up. Now I have a world class cylindrical lens and would never go back.

Quote:


I'm afraid that if I buy these cheap lens I will lose from quality of the picture. Don't see a reason to buy a native 1080p projector when I'll lose the most important thing on it - the quality. I can't realize why if there is nothing wrong with these surplus lens the people are buying lense for even 5000$...and so on...

The BK7 prisms from Suplus have NO correction, so you get CA, Astigmatism and GD.

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post #37 of 42 Old 11-11-2010, 07:44 AM
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As Mark states you get what you pay for. However, I believe the surplus shed prisms are heads and shoulders above your typical trophy prisms which cost about the same. The SS prisms offer an AR coating, and while yes CA is present in a grid it is not easily viewable in almost any regular image. I have noted it in very few instances (maybe twice) but that is because I am looking for it. I have never had a guest notice it, including during a AVS theater meet. As far as geometric distortion I have my image squared up very nicely by properly adjusting the tilt of the enclosure.

Now I know it is not the creme of the crop and Mark has helped me and others with questions, understanding and has been great in pointing out the differences between the basic lens' and the pro ones but I still say you get a lot of bang for your buck with Surplus Shed prisms.

If I could I would definately go for a pro lens because I understand all the benifits and advantages (even if everyone else wouldn't easily see it), even so when I sit and watch a great flick on my scope screen and know how I did it and for how much, it brings a smile to my face.
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post #38 of 42 Old 11-11-2010, 09:09 AM
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Be careful. Some anamorphic lenses reduce ANSI contrast greatly. I have not seen this problem with the better Panamorph or ISCO products. I believe a curved screen also helps improve ANSI by reducing side wall reflections.
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post #39 of 42 Old 11-12-2010, 01:54 AM
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Quote:
Originally Posted by umr View Post

I believe a curved screen also helps improve ANSI by reducing side wall reflections.

It would have to be a deeply curved screen to do that. The typical curves are like 2x the distance from projector to screen and the idea of a curved screen is actually to correct pincushion caused by the horizontally expanding lens.

If you guys want to improve image quality from the SS prisms, get yourselves a nice thick (chisel point) permanent marker and colour in the four non polished edges.

Mark Techer

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post #40 of 42 Old 12-18-2010, 07:46 PM
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Does anyone have any screenshots with the SS prisms?
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post #41 of 42 Old 12-20-2010, 07:32 AM
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I posted these in the French/SS prism thread, they wern't necessarily identified as SS prisms and since you asked.










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post #42 of 42 Old 12-27-2010, 05:22 PM
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Whilst the 2 prisms work, they do have many limitations when compared to a fully corrected lens.

This image was captured using my MK4.
LL

Mark Techer

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