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Larger images with aditional lense?

Discussion in 'Projectors, Screens & Video Processors' started by stuartsjg, Aug 30, 2004.

  1. stuartsjg

    stuartsjg
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    i have an AE200 and a 2.35:1 screen.

    When watching 16:9 or 4:3 the zoom is set for the smallest image (about 1.5m tall) and when watching a 2.35:1 (letterboxed) film i alter zoom to get the largest image and move the proj back about 1 ft to still get a 1.5m tall image. If i leave the proj sitting [for 16:9/4:3] my whole screen height isnt filled, its about 1.3m tall image and i dont like it - bigger is better.

    Im looking to ceeling mount and that will make making the proj back and forward impossible and i cant be bothered designing tracks etc. to slide it along the ceeling.

    Has anybody added a lense to projector to get a larger image?

    The existing zoom range is 1.0 - 1.2. I assume 1.2 is small image, 1.0 is large. Id like to maby make that 0.8(ish) - 1.2. with the addition of a lense.

    Id be happy adding and removing the lense so it doesent have to stay on all the time, this would allow the proj to remain fixed so: with no additional lense is 1.5/ tall 16:9 and 4:3...., adjust zoom and add a lense to get 1.5m tall 2.35:1.

    If anybodys done this could you let me know which lenses, where from and prices?

    Thanks,
    Stuart.
     
  2. Gary Lightfoot

    Gary Lightfoot
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    You make a good point regarding fixed height which is the norm for cinema viewing - the curtains retract to allow for the wider image but the height stays the same.

    It would be great if we could have the same thing at home, but current pj technology generaly means we have fixed width and variable height - not ideal but a compromise.

    Currently (as far as I'm aware), the only 'universal' lenses are the Isco and Panamorph/Prismasonic lenses which opticaly do what your pj does to anamorphic images - they squish or stretch the image to the correct shape.

    What may work here, is for 16:9 images, you allow your pj to do it's thing (to an anamorphic source) so the image fits the screen height perfectly - it's being compressed down to fit. When you get a 2.35:1 movie, you don't let the pj do the squish - you keep the image at full height so that it fits the screen height, but everyone looks tall and skinny. Now you flip the lens in front of the pj, and it will opticaly stretch the image sideways, just like at the cinema.

    Where-as this will work in theory, the issues you may find could be a slight image shift either up or down (a few inches) when the lens is moved in front of the pj, and possibly some enhanced image grain/artefacts, though I'm not entirely sure this will be the case.

    Here is a good source of a lens that will stretch the image sideways, and at a reasonable cost - you want the 'H' range (starting from 475euros):

    http://prismasonic.com/english/index.shtml

    http://prismasonic.com/english/prices_lens.asp

    Here is a discription with pictures:

    http://prismasonic.com/english/intro.shtml

    Gary.
     
  3. stuartsjg

    stuartsjg
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    Thanks for replying...

    Im not actually looking for an Anamorphic lense, as the PJ is 16:9 native i dont mind losing a bit resolution by enlarging the image for 2.35:1.

    As i said, currently i move the PJ back about a foot and zoom to get the largest image, this ensures that i get my 1.5m tall image all the time, nomatter what the input format is.

    I was looking for something like the wide angle lenses you get for camcorders thinking that would make the image larger... the only prob is that they are large ratos.

    the pj is 1.0 - 1.2 zoom (1.0 i assme gives a larger image, 1.2 the smaller) so i was looking to expand that from 1.0 to 0.8. The camcorder lense things are all about 0.5x which would be too large.

    Thanks,
    Stuart.
     
  4. LV426

    LV426
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    Am I understanding it right?

    When a wider-than-widescreen (eg 2.35:1) film is on, you enlarge (by moving the projector) the image so that it's height fills the screen (more or less) but you lose some of the left and right because it's now wider than the screen? i.e. arificially cropping part of the film?

    You could always buy 4x3 Pan & Scan editions of films - readily available on VHS.
     
  5. Darwock

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    I don't think he can mean that he loses the sides of the image (surely he can't? the projector would just display it on the furniture instead).. must have an extra wide screen.

    I found something about long and short throw lens attachments for Panasonics, but I can't remember where. By the way I think you've got the zoom amounts the wrong way round. 1.2 is 1.2 times the size, so is the bigger picture.
     
  6. stuartsjg

    stuartsjg
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    Theres no cropping, as i said in the origional post, i have a 2.35:1 Screen, that 1.5m tall by 3.5m wide.

    When watching something 4:3, 16:9, or 2.35:1 the whole hight of the screen is filled.

    When viewing a 2.35:1 film, which are always letterboxed and "enhanced for 16:9 desplays" i expand the image to fill the whole screen....
    In doing this, i have to alter the zoom and move the PJ back about 1 ft.

    The only time the whole screen is filled with image is a 2.35:1 film, 16;9 or 4:3 leaves blank bits at the side.

    I was wanting it to be like a proper cinema where theres a huge wide screen thats curtained off for not so wide films.

    I want to negate this moving the PJ so i can fix it to the ceeling, doing this i wont fill my screen even when adjusting the inbuilt PJ zoom so i require to add a lense that can make the image larger, my thoughts were for a camcorder lense that gave the cam a wider view... in reverese, when added to the PJ would effectively reduce the throw needed by just enough that i can get my extra foot withouth moving the PJ.

    Adjusing the angle for the offest wont be a prob.

    Hope this makes sence :)

    Stuart.
     
  7. LV426

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    I'm sorry, I confess to misreading your first post. I can't immediately think of a solution that is convenient and works. The only thing you might do is set it up so that, for 16x9 and 4x3 (ie full height) stuff, it's zoomed to its smallest size, and then zoom to its largest size for wider. But you'll also have to adjust the tilt and keystone to get this working right.
     
  8. Gary Lightfoot

    Gary Lightfoot
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    You can make it work using an anamorphic lens, but you wil need a way of making the 2.35:1 image fill the 16:9 height from the projector - an HTPC will do that for you, and if you can get the pj to not do the squish, then that will give you the height you need for the anamorphic lens to work by widening the image.

    Other than that, and unless you can get a lens as you suggest, I don't think it's going to be that easy.

    Gary.
     

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