CurtPalme.com Home Theater Forum

[hts]

I have had in a warehouse my PJ and now its time to put it into use.
It has HD10GT17, a green and red "C" element.
Screen is 16:9 183cm wide.
Using formula found here I calculated best distance to be about 285cm.
I measeured my HT room and its about 370cm long. So I should be able to set the screen and PJ to get that 282cm viewing distance.
Question is that did I calculated it correctly and what if viewing distance is less that the calculated?

[stridsvognen]

I think the screen is just to the small size.. I would use a screen minimum 200cm wide, or you will not be able to use all the tube and be inside focus range.

With CRT, and specially a tough CRT like you have,( The best ) i think you can sit as close to the screen as you like, so its more about personal taste than anything else.

[CasetheCorvetteman]

That's a pretty small room!!

[hts]

I really need to check what I have bought few years ago . Especially those lenses.
My main corcern was that the room is too small but according to you just bigger screen is enough.
Thats good news.
First i need to get the PJ to ceiling (I got motorized system).

Yes it the second bedroom and best option for my HT.

[stridsvognen]

If you hang the projector, i would sit right under it, just not get in front of the lens opening.

Im using a 90" 16:9 screen 200cm wide, and my 9553LC Ultra the lense opening is 250cm from the screen, and thats around 340cm from screen to the back of the projector.

Im using HD10E lenses, but i think its the same as my GT17 lense, at least its very close.

So i think its possible to hang it in your room.

[CasetheCorvetteman]

My room here is 6 metres deep, 3.4 meters wide, 125" 5:4 screen. Wouldnt want the screen any bigger!!

[hts]

I will hang the PJ and going to sit under it.
If I remember right i should get a 1.2 Gain screen.
Is 210cm x 118cm enough or is 230cm x 129cm better?
Both are 16:9.

[CIR Engineering]

Your best bet is to do a mock up first.

Hang the projector on the ceiling as far to the back of the room as possible. Then make a 16x9 image on the wall as large as you can using all of the face of the tubes. Once that is done, make sure it is a true 16x9. Finally measure the screen and order one that size or smaller.

This way you will get to use the most phosphor possible. This gets you the largest, brightest, and sharpest image possible.

craigr

[stridsvognen]

[CIR Engineering]

I would use a higher than 1.0 gain. Typically with CRT 1.3 gain is about the best for reference projection quality.

Basically gain works like this. Multiply the width of your screen times the gain number of the screen to find the best seating distance to make the gain invisible. For example, on a 2 meter wide screen with a 1.3 gain material, the ideal seating seating distance from the screen will be 2.6 meters (or further) back. For a 1.2 gain screen the best seating position would be 2.4 or more meters back.

As long as you sit back from the screen proportional to the gain number you will not get any negative affects from the screen gain. So with a 1.3 gain screen, as long as you sit 1.3 times the width of the screen back away, you can't see the negative gain affects. However, the gain is very beneficial because a 1.3 gain screen will be 30% brighter than a 1.0 gain screen.

Also, gain is very difficult to measure because it requires a reference for comparison. As a result many screen manufacturers exaggerate their gain. The only two companies that typically have correct gain ratings on their screens are Stewart (the best screens) or Draper. Dalite for example has gain ratings that are much higher. A Dalite gain screen of 1.3 is really around 1.1. A Carada screen gain rating of 1.0 is really more like 0.85.

craigr

[CasetheCorvetteman]

Craig, how well would it go on a Black Diamond screen?

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