Return to the CurtPalme.com main site CurtPalme.com Home Theater Forum
A forum with a sense of fun and community for Home Theater enthusiasts!
Products for Sale ] [ FAQ: Hooking it all up ] [ CRT Primer/FAQ ] [ Best/Worst CRT Projectors List ] [ Setup Tips & Manuals ] [ Advanced Procedures ] [ Newsletters ]

 
Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist  Photo AlbumsPhoto Albums  RegisterRegister 
 MembershipClub Membership   ProfileProfile   Private MessagesPrivate Messages   Log inLog in 
Blu-ray disc release list and must-have titles. Buy the latest and best Blu-ray titles to show off in your home theater!

Throw distance vs. screen size

 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> Home Theater Design & Construction
View previous topic :: View next topic  
Author Message
Pegasus



Joined: 29 Nov 2007
Posts: 18
Location: Spangdahlem, RP, Germany


PostLink    Posted: Thu Nov 29, 2007 1:58 pm    Post subject: Throw distance vs. screen size Reply with quote


        Register to remove this ad. It's free!
Hello all.

I would like your advice on installing my Sony VPH-1272Q in my new house in a difficult situation.

The main problem is that the projector must be located 187" (~15.5') from the (front) projection surface but the largest 1.33:1 screen I would like is 108"x81" (135" diag.) What's the best way to shrink the image to this size without causing much tube damage?

More details:

This is in my 13' vaulted-ceiling living room which has a ceiling fan that hangs down to 95" above the floor which my wife won't let me raise or otherwise move. Where the fan is, the beam will be about 41" tall (20" from center,) so I'll have to center the projector 75" above the floor. Not a problem, but the projection surface is still too large.
The projector must be located 187" (~15.5') from the (front) projection surface (because I'm building it into the wall because my wife doesn't want "an elephant hanging in the middle of the room.") According to PJCalc, this creates a ridiculously large screen (141"x106") which the other wall can't accommodate (slanted upper ceiling corners, furniture at the bottom, etc.)

Thanks for any advice!
Back to top
papalek



Joined: 08 Mar 2006
Posts: 1524
Location: Longs SC


PostLink    Posted: Thu Nov 29, 2007 3:33 pm    Post subject: Reply with quote

Get a new wife. Wink Mr. Green
_________________
My current list of PJ's AmPro 1 1/2-4600,4200, 1/2-3600,2600.
I do love my AmPro's
Back to top
View user's photo album (24 photos)
ecrabb
Forum Moderator


Joined: 13 Mar 2006
Posts: 15909
Location: Utah

TV/Projector: JVC RS40, Epson 5010


PostLink    Posted: Thu Nov 29, 2007 4:04 pm    Post subject: Reply with quote

Honestly, there's really no way to do that right. You're going to have to look at moving the projector to a different location or going to a digital with a long-throw lens that you can build into your desired wall location. Maybe you can post some pics of the room and we can see if we can think of anything else.

Have you considered an "in the coffee table" mount?

SC
Back to top
View user's photo album (10 photos)
WanMan



Joined: 19 Mar 2006
Posts: 10261



PostLink    Posted: Fri Nov 30, 2007 11:47 am    Post subject: Reply with quote

CRTs do not have a variable throw--they're fixed. Want a larger/smaller projected image, move the projector closer and farther away. If your wife is ignorant of this fact, then tell her you could always buy a comparable (lie like the ba$tard you are Razz ) digital projector for $10-20K. Give her the options.

What about floor-mounting it?

_________________
Trust no one. Absolutely no one. Advice of the board.
Back to top
AnalogRocks
Forum Moderator


Joined: 08 Mar 2006
Posts: 25398
Location: Toronto, Ontario, Canada

TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Fri Nov 30, 2007 11:06 pm    Post subject: Reply with quote

What about moving the screen closer? You could get a retractable screen motorized that comes down from the celing.
_________________
Tech support for nothing

CRT.

HD done right!
Back to top
View user's photo album (27 photos)
paw



Joined: 08 Mar 2006
Posts: 1176
Location: Arvada, CO


PostLink    Posted: Sat Dec 01, 2007 4:30 am    Post subject: Reply with quote

Stewart make a wall climber. I think that was want it was called. The case descend via cables and then the screen descends. That way you don't have 6 ft of black leader and then the white screen.
_________________
Aubrey
Back to top
View user's photo album (8 photos)
AnalogRocks
Forum Moderator


Joined: 08 Mar 2006
Posts: 25398
Location: Toronto, Ontario, Canada

TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Sat Dec 01, 2007 6:54 am    Post subject: Reply with quote

sounds like a good design
_________________
Tech support for nothing

CRT.

HD done right!
Back to top
View user's photo album (27 photos)
Pegasus



Joined: 29 Nov 2007
Posts: 18
Location: Spangdahlem, RP, Germany


PostLink    Posted: Sat Dec 01, 2007 1:04 pm    Post subject: Hmm Reply with quote

Thanks for all the input, folks!

I guess what I wanted to know is can I get long-throw lenses for this PJ?

I have considered a floor/coffee table mount, and now that we actually have a coffee table with a space underneath that would fit the projector, but the screen would then be too small (69" diag...can I get short-throw lenses?) because the table is only 6.5 feet from the wall (and would hit the couch if moved back further.) I could live with 69" if I can increase the projection angle.

How do I do the "minor electrical modification" PJCalc mentions to increase the angle of projection to 20 degrees or more?

I've also thought about a wall-climber (if that's the motorized deal that lowers the projector into place when you want to use it) but how much do those cost?! (The screen will be fixed to the wall so it can be stationary.)
Back to top
WanMan



Joined: 19 Mar 2006
Posts: 10261



PostLink    Posted: Sat Dec 01, 2007 7:02 pm    Post subject: Reply with quote

The only other option I can offer is identify a wall and make a massive rear-projection setup. I knew there was a thread on AV$ from three years ago, but I cannot give any details. I think the individual had a partition wall (interior on both sides) that he opened up.
_________________
Trust no one. Absolutely no one. Advice of the board.
Back to top
GEBrown



Joined: 08 Mar 2006
Posts: 729
Location: Denver


PostLink    Posted: Sat Dec 01, 2007 7:22 pm    Post subject: Re: Throw distance vs. screen size Reply with quote

Pegasus wrote:
. . .
I would like your advice on installing my Sony VPH-1272Q in my new house in a difficult situation.

The main problem is that the projector must be located 187" (~15.5') from the (front) projection surface but the largest 1.33:1 screen I would like is 108"x81" (135" diag.) What's the best way to shrink the image to this size without causing much tube damage?

. . . .

In my opinion, and I have had a couple of 1272's, you need to either get a different projector or get a different room setup.

In the first place, I don't know of anyone who will recommend a 1272 onto a 108" wide screen. You won't be happy with that - 80-84" is generally considered the maximum width screen for a 1272, though I have no doubt someone will pipe in and say "But MY screen is XXXXXX inches wide and it looks GREAT to me!!!" If so, you should try to go see their set up before you try to mimic it.

9ft (108") wide screens are generally considered to be the realm of the 9" CRT's - a 1272 is considered to be an 8" CRT with 7" electronics - kind of a hybrid. Don't get me wrong - they look GREAT on an 80" wide screen - I was SOOO proud when one of the experts here saw my setup and was impressed!!! (Thanks DraganM!!) But I've moved on to a true 8" setup now (Marquee 8500) and I won't look back!!

The other problem with your geometry is the throw distance. Almost all the projectors commonly in use have an optimal throw distance of 1.2 - 1.3 x screen width. At a screen width of 108" (9ft) your optimal throw distance is going to be around 140" plus or minus a few inches. But you are looking at 47" beyond that!!! Even with a 9" projector and some special lenses, I don't think you can optimize your raster at that throw distance.

It seems to me you're trying to fit a square peg into a round hole. It just isn't going to work.

Sorry to be so negative, but I'd hate to see you spend a lot of money and time on a project that is doomed from the beginning.

_________________
Member of the Marquee Maniacs Club
Back to top
Pegasus



Joined: 29 Nov 2007
Posts: 18
Location: Spangdahlem, RP, Germany


PostLink    Posted: Sun Dec 02, 2007 12:07 am    Post subject: Re: Throw distance vs. screen size Reply with quote

GEBrown wrote:

In the first place, I don't know of anyone who will recommend a 1272 onto a 108" wide screen.


Hehe, I've had this projector for a few years now and in my last house had it on a 130" diagonal drop cloth! (I just lived with the softness because the cloth would move anyway when people got near it.) But your point is noted. I was just saying that's the largest size I can have, but am open to smaller. If it kicks butt at 80", 80" is fine. (Is that 80" wide or diagonal?)

Quote:

It seems to me you're trying to fit a square peg into a round hole. It just isn't going to work.


Yeah, I've been thinking that. I just wanted confirmation from you guys. Mr. Green

Ooh...how about mounting the projector on the ceiling at a 35 degree angle or so and just accept the non-optimal raster usage resulting from trapezoid correction? Certainly that would be better than having it too far away?

(Keep in mind this projector has like 7000 hours on it (and three different installations) and the blue tube wear is starting to be noticable. (yellowish tint.))
Back to top
Joust



Joined: 05 May 2006
Posts: 2430
Location: Almonte, Ontario, Canada

TV/Projector: Marquee 8501LC


PostLink    Posted: Sun Dec 02, 2007 12:22 am    Post subject: Reply with quote

WanMan wrote:
CRTs do not have a variable throw--they're fixed.

there is no real technical reason why not.
The digitals simply have a lens that accomodates this feature. CRTs could have similar lenses. Granted they would be bigger and more expensive.
Back to top
View user's photo album (1 photos)
GEBrown



Joined: 08 Mar 2006
Posts: 729
Location: Denver


PostLink    Posted: Sun Dec 02, 2007 4:56 pm    Post subject: Re: Throw distance vs. screen size Reply with quote

Pegasus wrote:
Hehe, I've had this projector for a few years now and in my last house had it on a 130" diagonal drop cloth! (I just lived with the softness because the cloth would move anyway when people got near it.) But your point is noted. I was just saying that's the largest size I can have, but am open to smaller. If it kicks butt at 80", 80" is fine. (Is that 80" wide or diagonal?)
. . . . .
Ooh...how about mounting the projector on the ceiling at a 35 degree angle or so and just accept the non-optimal raster usage resulting from trapezoid correction? Certainly that would be better than having it too far away?

(Keep in mind this projector has like 7000 hours on it (and three different installations) and the blue tube wear is starting to be noticable. (yellowish tint.))


I was referring to 80" wide which gives you a 92" diagonal measurement (OK, 91.7877987534.... for the purists Very Happy )

I'd like to see Wallace or SonyNut pipe in here, but I think at 35 degrees, you may not have enough keystone adjustment to get the image square on the screen and it will be difficult to get the top and the bottom of the screen both in focus. If it will square up, then yes that would be better. You want to use as much phosphor as possible to get the brightest image that you can at the lowest contrast setting that you can.

HTH

_________________
Member of the Marquee Maniacs Club
Back to top
Pegasus



Joined: 29 Nov 2007
Posts: 18
Location: Spangdahlem, RP, Germany


PostLink    Posted: Mon Jan 14, 2008 7:48 pm    Post subject: Going to go for trapezoid Reply with quote

Well, after much thought and discussion, I'm going to try mounting it to the ceiling high up. I contacted Sony but they don't have any info on electrically adjusting the throw angle, so I'm stuck with the factory 14.5 degrees. They said all I can really do is physically pitch the projector downward and use keystone correction. So that's what I'll do. (Maybe tilt the screen upwards a couple degrees to make it a little easier.)

Gonna do the DIY screen mentioned on this site...screen material is on order!
Back to top
ecrabb
Forum Moderator


Joined: 13 Mar 2006
Posts: 15909
Location: Utah

TV/Projector: JVC RS40, Epson 5010


PostLink    Posted: Mon Jan 14, 2008 11:52 pm    Post subject: Reply with quote

You don't have to use the factory throw angle of 14.5 degrees. That's a standard spec, but you can use any throw angle between zero, and (according to PJCalc) 25 degrees. Would it be optimal at 25 deg? No. Would focus be as good? No. But, you certainly don't have to stick right at 14.5. or guess what you can and can't do. I'm pretty certain my throw angle isn't exactly 14.5. I'll have to measure and see what it is some time.

Have you played with PJCalc 1.8? You can put in your screen size and then play with PJ-screen distance and throw angle dynamically. It will even give you alerts about which washers and shims will be required when you make a change that affects those things.

SC
Back to top
View user's photo album (10 photos)
AnalogRocks
Forum Moderator


Joined: 08 Mar 2006
Posts: 25398
Location: Toronto, Ontario, Canada

TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Tue Jan 15, 2008 2:06 am    Post subject: Reply with quote

How high up do you intend to mount it? You could always drop it down on a pole too. Idealy you want the lens centres inline with the top of the screen.
_________________
Tech support for nothing

CRT.

HD done right!
Back to top
View user's photo album (27 photos)
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> Home Theater Design & Construction All times are GMT
Page 1 of 1
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum