Started my 110" Wide DIY Curved Screen Build - Page 3 - AVS Forum | Home Theater Discussions And Reviews
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post #61 of 71 Old 02-11-2010, 10:40 PM
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Quote:
Originally Posted by stegen View Post

Now the next question is whats a anamorphic lens?

Basically an anamorphic lens is one that magnifies (or compresses) only in one directions - typically horizontally. Horizontal Expansion is the most popular and the other type is a Vertical Compression lens.

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post #62 of 71 Old 02-19-2010, 03:53 PM
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This has been an interesting read. Thanks for posting.

I just purchased my first projector and I hate to admit that right now I'm watching my movies on a white sheet hanging on the wall. And the projector (HD65) is sitting on a cart in the middle of the floor. It is about 12' back and I'm shooting roughly a 110" diag. The room is about 11' w by 23' d with a 7 foot ceiling. I've looked through my movies and would guess about 2/3 of them are 2.35 to 2.4, the rest being 16:9-ish. So I'm thinking about trying to make the anamorphic lens with the crystal wedges.

I've read your comments about the purpose of a curved screen and have a question. You indicated that you shouldn't use it if you are not using an anamorphic lense. If you are watching a 16:9 on the curved screen (without the 2.35 lens), do you get the distorted picture on it?
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post #63 of 71 Old 02-19-2010, 07:42 PM
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Quote:
Originally Posted by NebrGuy View Post

If you are watching a 16:9 on the curved screen (without the 2.35 lens), do you get the distorted picture on it?

The curved screen is intended to remove pincushion distortion by adding barrel distortion (as they are opposites). If there's no pincushion to remove, all you have is barrel.

If that's not clear, check out the images here: http://en.wikipedia.org/wiki/Distortion_(optics)
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post #64 of 71 Old 02-20-2010, 06:00 AM
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I've looked at the picture and previously read the descriptions of the barrel and pincushion distortions and I realize I probably worded my question incorrectly. Sorry about that.

For those who use a curved 2.35 screen, do you watch any 1.7 content on it? The reason I ask is because it appears the barrel distortions are the greatest at the edges of the screen. If my math is correct and you are watching 1.7 content on a 2.35 screen then you have roughly 28% of the screen's width that is not being used...14% on each side.

So my second question would then be IF you are watching the 1.7 content on a 2.35 screen, is the picture width small enough that you don't notice the barrel distortion? or is it a distraction?
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post #65 of 71 Old 02-20-2010, 11:42 AM - Thread Starter
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Hey Nebrguy,

No shame in utilizing the sheet to make the most of your projector right now. If you look at my HT build thread you will see that the good ole bedsheet is what I utilized for quite a while and that includes hosting a superbowl party a couple of years ago.

I normally leave my lens in place all the time wether watching scope of 16:9/1:78. I can add pillars to the sides shrinking the image back to a 16:9 aspect with the lens in place, but I don't do that and for the most part watch 16:9 material in scope and my son and his friends do their gaming in scope as well.

If I were to display 16:9 and remove the lens you will see the bottom and top edges on the left and right warp/curve up and down. It does so coming in about 6-8 inches from each edge of the image. For me it is definately a distraction and I prefer to leave lens in place and squeeze the image or leave it set to scope. Hope this answers some of your questions.
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post #66 of 71 Old 02-20-2010, 03:46 PM
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Thanks, Oman. You even answered something I hadn't asked. Appreciate your response. I went to the store and bought me a few yards of BOC today and then to the lumberstore for some wood. My first attempt of a screen will be a flat screen, but I'm intrigued by what I'm reading on 2.35. I'm sure this won't be my last build, but for $40 worth of material I figure I can play around and see what gives. I really like the looks of your screen. Thanks again for the reply.
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post #67 of 71 Old 02-22-2010, 07:30 AM - Thread Starter
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Thanks for the compliment NebrGuy, glad I could be of help.

At first I was intimidated at trying to build my first real screen and curving it to boot. It turned out to be one of my most enjoyable projects from the entire HT build. Seeing it come together was pretty cool and goind acoustically transparent so I could place the speakers behind was/is definately worthwhile.

If you have further questions feel free to ask.
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post #68 of 71 Old 04-07-2010, 11:27 AM
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Oman321,

Greetings! You've posted a couple times on my new build thread so id thought id pop over here and see what your 110" curved screen build looked like because i am considering building my own screen as well to save on cost. (always on a tight budget)

I've got to say that screen is incredible. It turned out really nice!

My brother in law has an amazing cinecurve screen, the ones with the panels that automatically scootch in from the sides to go from 2.35:1 to 16:9. So I've been toying with the idea of making something similar but with manual adjustments.

Basically adding black material on a track that can be pulled in or out to change the aspect ratio of my screen. i know the thought of having to get up out of my chair to change it is daunting but hey...you gotta exercise some times right?

just wondering what your thoughts one something like that would be having built your own screen. Think its doable without being cheesy? or not worth the effort?

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post #69 of 71 Old 04-07-2010, 11:53 AM - Thread Starter
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Thanks premier, definately worth while. I've considered adding such masking techniques and if done right you can easily automate it now or in the future. It's really one of those back burner type things though as there are still to many things going, especially now that I'm in the midst of rebuilding since I had a flood issue recently.

Here are some links from this part the forum for some great masking techniques both automated and manual.

One of my favorites:
https://www.avsforum.com/avs-vb/showthread.php?t=941076

Another good one.
https://www.avsforum.com/avs-vb/showthread.php?t=1229614

There are probably some more in the DIY Screen section. If you end up going manual there is nothing wrong with that, in fact one of the screen companies and another one soon are offering manual inserts that you just set in place. To make things easier think about postioning the left and right speakers at the inside of the 16:9. Less to worry about as far as acoustic transparency if your doing an AT screen.

The other option which I often employ, (and I know it's taboo) is that I often set 16:9 content to 2:35. Only once or twice did it seem wrong and I collapsed it back to 16:9, otherwise gaming and tv shows are usually set to scope. Just leave the lens in place for 16:9 content with no v-stretch. If you plan to zoom that obviously wont work.

Good luck.
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post #70 of 71 Old 04-13-2010, 06:05 PM
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Oman,

Do you have a link to the spline you used to attatch the screen. Im not following how that worked...

Or...you are so good at explanations, could you elaborate on how the spline worked? and how its held up as far as keeping the screen properly tensioned?

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post #71 of 71 Old 04-13-2010, 06:40 PM - Thread Starter
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The spline is just off the shelf spline from Home Depot or Lowes. I just grabbed the screen track (also available at Home Depot) and tried to fit the spline into track while it was still in the plastic bag to help account for the screen material.

I've had the screen up for a couple of years now and it has held up tremendously well. I haven't had to adjust it or anything and there is no evidence of sagging or loosening up. To boot I have taken the screen down several time and I am confident that it will hold up ok.

The best thing that I did was to cut small pieces of spline and secured the screen material all around and then I could secure the screen all around with one long piece of spline while streching the screen and removing the small pieces.

It's the same as rescreening a window screen just on a bigger scale.
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