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How to convert 4:3 to 16:9??

Discussion in 'Projectors, Screens & Video Processors' started by Ken, Dec 1, 2004.

  1. Ken

    Ken
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    I have a 2m wide 4:3 Owl screen.
    Does anyone know if it possible to spray the screen with some sort of black paint, to make it a 16:9 screen? Obviously the paint would have to retain flexibility.
    Any advice or experience would be much appreciated.

    Ken
     
  2. fortean

    fortean
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    Hi Ken,

    Why not adjust the low level drop so the screen stops 187mm higher than it does now.
    Before you do that though get 2000mm x 375mm of black felt and tape it to the top of the screen in 4:3 mode. When you take the screen up 187mm you will have about 188mm of felt still hanging down to make up your top border. Screen centre will still be where it belongs. This way you don't spoil your screen with paint and can remove the felt whenever you want.
     
  3. cyberheater

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    I'm still thinking this thru but it's a cracking idea! Nice one :thumbsup:
     
  4. Ken

    Ken
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    Thanks for the reply fortean; I thought of that, but wasn't sure if the felt would get itself tangled up when the screen was lowering.
    The area of screen that is showing is quite a bit more than you suggest; as it drops from the ceiling, and is probably more like 4:4; but the principle could be applied if there is no danger of it getting caught up.

    Ken
     
  5. fortean

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    You have a point about it getting stuck. After having a close look at my screen it seems a little bad luck could really mess things up.

    Anyway, I will be trying a multi format conversion on my 4:3 screen this weekend. If it works as I expect then it will be suitable for your screen. The method will avoid the tangle, getting stuck, issue.

    I will post a result, good or bad.

    Regards, John.
     
  6. Ken

    Ken
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    Waiting with anticipation.

    Ken
     
  7. fortean

    fortean
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    Update on a multi-format retrofit to a 4:3 Owl electric screen...

    So far all the testing I have done has gone better than I hoped. It's so simple I can't understand why I havn't read about it on here. As the screen lowers the top mask lowers with it. Once the screen gets to the half way point the mask starts to go up at the same rate as the screen goes down. This allows the screen to be stopped at any aspect ratio.
     
  8. patt

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    HI get some paint for fabric black ,mask up the screen paint on and job done
     
  9. cyberheater

    cyberheater
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    I don't get it. Any chance of posting a picture.
     
  10. Ken

    Ken
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    Fortean,
    Can't work out how you are doing that.

    Patt,
    Have you tried this, does the paint adhere properly to the screen?

    Ken
     
  11. patt

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    Yes i have the paint i had was from dunelms ,it is dylon fabric paint like i said mask up and paint on then to fix iron on hot for 2 minutes,fabric returns to it softness i did not iron was no need and has no come of
     
  12. fortean

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    I have put a movie of the first prototype on my website at www.4tn.net/homecinema/ in AVI MPG and WMV formats. It shows an Owl 4:3 electric 7ft screen modified to multi-format. Cost of modification under 20 GBP.

    I still need to find a better material. Used black felt for this one but I need to find something better.

    I will post instructions once I have written them and ironed out a few problem areas.

    I have started a thread in the DIY section where I will post details and pictures.
     
  13. Ken

    Ken
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    Fortean,
    That's pretty impressive and a very simple idea.
    I would never of thought of doing it that way.
    I suppose that with enough weight on the felt and securely fixed to the back of the screen it will not try to follow the screen when moving against it.
    Very clever.

    Ken
     
  14. fortean

    fortean
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    Ken,

    I used a piece of plastic trunking at the bottom but that was to give it a straight edge. It worked fine without anything but the felt had stretched when I pulled it through.

    For the next one, on my 8ft screen, I will use a length of 6mm dowel.

    As the screen drops the mask unrolls with the screen then it's pulled over the top and down the back. When the screen closes the friction of the mask on the screen allows the screen to take it back round.

    I used double sided tape to secure it to the back. I am testing some adhesives now.

    There is a light source behind the screen in the video which is why you see the mask shadow. This won't be seen under normal use.

    A collegue of mine is making me a remote control to stop the screen automatically at each aspect ratio. This is a retro fit for a screen without remote control with an anticipated build cost of 30 GBP.
     
  15. Clint C

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    C'mon fortean, we're all waiting with baited breath here... :D More details :lease:
     
  16. Ken

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    I really like your invention Fortean, and the hardest bit in making it, is probably getting the felt through the screen housing, but I will most likely use the fabric paint option, as I use a HTPC for my viewing, and do the positioning in software; although this does leave a varying size of black bar at the top, I prefer the bottom of the image to stay at the same level.
    Thanks for your input, I am sure many others will benefit.

    Ken
     
  17. fortean

    fortean
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    How I did it....

    The first thing to do is determine the length of the masking material and the fixing position at the back of the screen.

    I did this with wrapping paper about the length of the screen height when fully down.

    With the screen fully down sellotape a couple of pieces of string to the back of the screen near the top. Leave about 12 inches of string hanging from above the sellotape and be sure that the bottom of the string hangs below the bottom of the screen.

    Now take your screen up about 18 inches or so. The string is pulled over the screen roll inside the case and will start to roll up. Next drop the screen a little at a time. The ends of the string above the sellotape should drop through the slot at the front of your screen. You should now be able to pull the string through until you have the end of it. Now roll your screen up again, making sure that the string doesn't disappear back inside, and remove the sellotape from the back of the screen.

    You now have two pieces of string going up and over the screen roll inside the case and out down the back. Tape your wrapping paper to the string and pull it through. It's easier to pull the paper through from the front to the back.

    Do not remove the string from the paper, this is your emergency paper retrieval system should things go wrong.

    You can now sellotape the paper to the back of the screen at approximately the halfway mark. Once you have done this you should close your screen fully. The paper will drop at the front as it rises at the back until the taped part is inside the case. It will then start to roll up with the screen. If you have used a long enough piece of wrapping paper it will be left hanging out the bottom. You should also still have the ends of the string hanging out at the back. Watch both the paper and the string as you roll up the screen.

    Now mark the paper level with the bar at the bottom of the screen. Open the screen to its half way point. Mark the paper again where it's level with the bottom of the screen. Now lower the screen fully to its normal 4:3 size. As you do this the paper will be moving up again. Mark the paper below the slot in the case.

    You now have 3 marks for top, middle and bottom. You need to get these marks to be the same for all three positions. This is done by trial and error by adjusting the bonding position of the paper at the back of the screen up or down a little at a time. If your top and bottom marks are 2 inches apart you should adjust the bonding point by 1 inch.

    Once you have marked the bonding position on the back of the screen and marked the mask length on the paper you can cut the paper down to the correct size. Now attach 2 pieces of string to the paper at the front of the screen and tie on some washers or similar to act as a counterweight whilst you test everything using the paper. If anything goes wrong you still have string attached to help retrieve the paper.

    The rest is down to you now. Choose a suitable masking material, I'm going to try velvet next, cut it down to size leaving an extra 1 or 2 inches for your mask counterweight bar and attach it to the screen where the paper was attached.

    This was the most difficult part for me as the material is the width of the screen. I used 4 lengths of string but because I was using felt it stretched as I pulled it through. When bonding to the back of the screen I recommend that you fold the edge to be bonded up so it is between the mask and screen. This means that as the mask is pulled down it pulls against a fold in the mask but when it is rolled up there is no fold in the masking fabric. Take care when bonding that you do not cause any distortion in the screen surface. You may notice when using the sellotape and paper that distortion occurs. This is because you will have stretched the sellotape as you applied it and it wants to shrink back again.

    Good luck and please post some results.

    The diagram shows a representative side view of the screen closed, half way and open. The screen is black and the mask is red.
     

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  18. Ken

    Ken
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    Fortean, you could tape the felt/velvet to the wrapping paper so it would be pulled through evenly.

    Ken
     
  19. fortean

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    Yes I think you could Ken. That's how I am going to try it this weekend with velvet.
     
  20. Clint C

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    fortean, thanks for the info. Excellent work BTW. One thing though, when I looked at the movie of it in motion on your website, it looks like it's clear to see where the masking is attached to the back of the screen. Is this the case or is it the light just catching it. What I'm saying is that it looks like the adhering to the back of the screen is stressing the screen and would subsequently have an effect on the picture. Does this make sense?

    I look forward to your response.

    Clint.
     
  21. fortean

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    Clint,

    The fluorescent light behind the screen causes the shadow at the back. My first test was done with the screen mounted in the living room; I also projected on to the screen too. There was no indication of shadow then. When I first attached paper to find the correct bonding point I did get some screen distortion but I put that down to the tape being stretched a little as I applied it then shrinking back again. I used double-sided tape for the one in the video and was more careful on how I applied it. So far no distortion has occurred on the one in the video. The bond is effectively holding a maximum weight of 5 grams per centimetre but that is assuming it has to hold all the masking cloth. In reality, the cloth is mostly held by friction as it lies on the roll of screen. The only time the bond has to hold the full weight of the cloth is during the transition from going around the screen roll to being rolled up with the screen.
     
  22. Clint C

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    Excellent, thanks again for the idea and info. I shall definitely be trying this out at some point and will get back to you on my progress.

    :smashin:

    Clint.
     
  23. fortean

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    For anyone that is concerned about bonding the masking fabric to the back of the screen you can add a false back to the screen...

    Lower you screen to maximum.
    Bond a sheet of thin fabric, a little smaller than your screen width, to the back of your screen at the very top. This should be outside of the viewing area.
    Allow the fabric to settle overnight.
    Raise the screen almost all the way up.
    Bond the bottom of the fabric to the bottom of your screen, outside the viewing area again.
    When you lower the screen this new backing may sag a little but you can attach your mask to this instead of the screen.

    Be sure when you do this that as you raise the screen the first time there is sufficient space within the case for the addition thickness created by the false back and mask in the roll.
     
  24. fortean

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    I have now converted my new Owl screen using the false back method. Total cost about £35 plus some sewing. I will post a new video of it at http://www.4tn.net/homecinema/ this weeekend. In the meantime there are some pictures. If you downlaod the pictures and use a graphics program like Corel to adjust the gamma you will see more detail.
     

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  25. fortean

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  26. Gary Lightfoot

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    That has got to be one of the most simple yet brilliant ideas I've ever seen!!

    Haven't any of the screen manufacturers done anything like this? If not, you could make a mint from the patent. :)

    Gary.
     
  27. sergien

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    What fabric are you using for the false back??
     
  28. fortean

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    I think it's cotton. May have polyester in it too. Curtain lining material, thin, cream colour and not stretchy. The mask is lined black velvet. I was thinking about using pond liner for the false back. I may still try it.

    Whatever material you use be sure to iron it (if it's not pond liner) and not allow it to crease when you fix it to your screen. I got creases in the screen fabric first time. It is a thin screen fabric though. Having said that the only time I could see the creases was when the screen was illuminated from the side.

    One more thing. Don't iron it on the dinning room table. It took me longer to re-polish the table than make the mask. Thankfully my wife was out when I did it.
     
  29. Clint C

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    Fortean

    Would you say that this system is to be avoided with a manual screen setup? I can see how it's perfect for electric but maybe all the tugging of a manual screen will cause some kind of stress to the screen with the extra weight? What do you think?

    Clint.
     
  30. figlio

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    I have used a black roller blind to create the masking.With a roller blind you can adjust for every ratio that can exist (1:85,2:35,2:45 etc)

    Hope this helps
     

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