A couple general projector questions - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 24 Old 11-29-2006, 04:38 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
If you are told that your projector should be 6' away, should you place it so that the lens of the projector is 6' away?

Since the lens on my soon-to-have Sanyo PLV-Z5 is not horizontally centered in the base of the projector, should you place it so that the vertical centerline of the lens is in line with the vertical centerline of your screen?

I have read that when ceiling mounting a projector, you should turn it upside down. Does the image automatically reverse so its not displayed upside-down? Also, are there mounting holes on the bottom of the projector?

How do you move the projected image up & down and side to side without physically moving the projector?

THANKS

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
Sponsored Links
Advertisement
 
post #2 of 24 Old 11-29-2006, 04:49 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

If you are told that your projector should be 6' away, should you place it so that the lens of the projector is 6' away?

Yes.
Quote:


should you place it so that the vertical centerline of the lens is in line with the vertical centerline of your screen?

Yes.
Quote:


Does the image automatically reverse so its not displayed upside-down?

The InFocus IN7x series does that. Otherwise there is a menu option.
Quote:


are there mounting holes on the bottom of the projector?

Yes.
Quote:


How do you move the projected image up & down and side to side without physically moving the projector?

Most ceiling mounts have "tilt and swivel" adjustments:


"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #3 of 24 Old 11-29-2006, 04:56 PM
AVS Special Member
 
Ian Fleet's Avatar
 
Join Date: Dec 2002
Location: Canada
Posts: 1,049
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The measurement for throw distance is from the lense to screen.
You'll want to line the projector perfectly perpendicur to the screen. For the height generally the projector is a couple of inches below the screen. If you want the projector higher you can tilt it down and correct in the menu using the keystone feature.
I think the Sanyos have a lens shift feature.
The projector menu will flip over the picture when you hang it from the ceiling.
Ian Fleet is offline  
post #4 of 24 Old 11-29-2006, 05:29 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Ian Fleet View Post

I think the Sanyos have a lens shift feature.

What is a lens shift feature?
Quote:


For the height generally the projector is a couple of inches below the screen.

You mean a couple inches below the ceiling?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #5 of 24 Old 11-29-2006, 05:56 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by Ian Fleet View Post

For the height generally the projector is a couple of inches below the screen.

This is not accurate. Most projector lenses are several inches above the top of the screen (for ceiling mounted projectors); the actual distance above is called the "offset" and it is expressed as a per centage of the image height and has nothing to do with zoom or throw distance! The offset per centage is dependent on the projector model but can vary a lot so you must select your projector with ceiling height and image size clearly in mind.

Quote:


If you want the projector higher you can tilt it down and correct in the menu using the keystone feature.

You want to avoid keystone correction if at all possible for the best image. This means you must have the projector level and perpendicular to the screen and mounted at the correct height. Normally, you mount the projector first and the screen second!

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #6 of 24 Old 11-29-2006, 06:18 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by cavu View Post

This is not accurate. Most projector lenses are several inches above the top of the screen (for ceiling mounted projectors); the actual distance above is called the "offset" and it is expressed as a per centage of the image height and has nothing to do with zoom or throw distance! The offset per centage is dependent on the projector model but can vary a lot so you must select your projector with ceiling height and image size clearly in mind.

You want to avoid keystone correction if at all possible for the best image. This means you must have the projector level and perpendicular to the screen and mounted at the correct height. Normally, you mount the projector first and the screen second!

Could you just create like a shelf for the projector and use rubber triangular wedges to angle to projector?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #7 of 24 Old 11-29-2006, 06:27 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

Could you just create like a shelf for the projector and use rubber triangular wedges to angle to projector?

Yes, you can create a shelf but it must be high enough so that the projector can be flipped upside down and mounted level. This can be done by using small stick-on rubber feet to keep the projector buttons from touching the shelf.


"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #8 of 24 Old 11-29-2006, 07:51 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
So how do I find the offset of my PLV-Z5?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #9 of 24 Old 11-29-2006, 08:15 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

So how do I find the offset of my PLV-Z5?

It ought to be in the user guide or installation manual, either as a chart or spec.

I believe the Z5 has considerable lens shift available: a full screen height up/down and a half screen width left/right. This should make it very adaptable but I don't know the default axis offset.

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #10 of 24 Old 11-29-2006, 09:42 PM
AVS Special Member
 
jrwhite's Avatar
 
Join Date: Feb 2004
Location: Indian River, Ontario, Canada
Posts: 1,546
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
I think cavu missed your 'what is lens shift' question.

cavu's examples are correct for 'fixed offset' projectors, like most inexpensive DLP's. His diagrams are great for explaining of what 'offset' is.

Most inexpensive LCD's have a 'lens shift' feature which can be thought of as 'variable offset' Lens shift allows you to place the projector ( either right side up, or upside down ) anywhere between several inches below the screen to several inches above, and shift the picture to up or down to fit your screen using the lens shift. ( you can also do this for a left or right offset ). How much above or below is a percentabe of the height of the projected image. The percentage varies by projector model. I belive the Z5 will allow you to place the projector above or below the screen by about 50% of the screen height. So, if you screen is 50" high, then you can place the projector up to 25" above ( or below ) the top ( or bottom ) of the screen.

It should be noted that the very best quality image from these LCD's is obtained if the projector is in the middle of the screen. The use of maximum lens shift can result in some geometric distortion of the image ( top or bottom bowed ) as well as poor brightness uniformity. ( brighter at the top or bottom ).

Jonathan
jrwhite is online now  
post #11 of 24 Old 11-30-2006, 10:31 AM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by cavu View Post

It ought to be in the user guide or installation manual, either as a chart or spec.

I believe the Z5 has considerable lens shift available: a full screen height up/down and a half screen width left/right. This should make it very adaptable but I don't know the default axis offset.

So lens shift is just moving the projected image up & down and side to side? Does it affect PQ? Does it offset the picture so that you will have to use keystone correction?

Does lens zoom affect PQ?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #12 of 24 Old 11-30-2006, 11:20 AM
AVS Addicted Member
 
rboster's Avatar
 
Join Date: Jul 2000
Location: USA
Posts: 17,833
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 145 Post(s)
Liked: 115
I did a search within the Z5 master thread for a copy of the manual. Here is the manual and should answer all your questions:

http://sanyoservice.com/pdf/images/PLVZ5.pdf

"Retired" AVS Moderator
Feeler: I'm thinking of selling my JTR Triple 8HT's Let me know if you are interested?
For Sale: ACS PlanarTrap (freestanding acoustic panel) ($300/pair)[/B]:
http://www.avsforum.com/forum/209-au...tic-panel.html
rboster is online now  
post #13 of 24 Old 11-30-2006, 01:25 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

So lens shift is just moving the projected image up & down and side to side? Does it affect PQ?

That is correct and it doesn't affect the PQ much if used in moderation.
Quote:


Does it offset the picture so that you will have to use keystone correction?

You would not need keystone correction when using a moderate amount of lens shift.
Quote:


Does lens zoom affect PQ?

Yes!

Maximum zoom gives you the rated brightness but loses about 17% of the rated contrast ratio.

Minimum zoom is exactly half the rated brightness (1 f-stop), but gives you the best focus and best contrast ratio.

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #14 of 24 Old 11-30-2006, 02:36 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:


Maximum zoom gives you the rated brightness but loses about 17% of the rated contrast ratio.

But as you increase zoom, you decrease the distance from the screen to the lens. So wouldn't that tradeoff mean you get equal brightness at any zoom level?

Quote:


Minimum zoom is exactly half the rated brightness (1 f-stop), but gives you the best focus and best contrast ratio.

So if you use no zoom at all, then you get half brightness? If the calculator on projector central says the screen size you have chosen is right for dark rooms (I do have a dark room), does it factor in the possibility that you may use minimum zoom and lose half the brightness?

Do most people use zoom when setting up their projector? I had no idea you could actually lose brightness by not using zoom...

Does lens zoom affect PQ in any other way? Like loss of detail/colors or image distortion?

BTW, if I have a room with 3 windows which will be covered with heavy drapes, can that be considered a dark room?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #15 of 24 Old 11-30-2006, 02:53 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

But as you increase zoom, you decrease the distance from the screen to the lens. So wouldn't that tradeoff mean you get equal brightness at any zoom level?

No. Light loss over the distance we are talking about is of no consequence!
Quote:


does [projector central] factor in the possibility that you may use minimum zoom and lose half the brightness?

No. Even most of the reviewers do not recognize the fact!
Quote:


Do most people use zoom when setting up their projector?

Don't know about "most people".

Those looking for best PQ use minimum zoom (smallest image) because it provides better contrast and better focus.
Quote:


I had no idea you could actually lose brightness by not using zoom...

It's spelled out right in the projector specification but "most people" ( ) don't understand the significance: the Z5 lens F-stop varies as the zoom is adjusted from F2.0 to F3.0 ... a full F-stop ... which represents a halving/doubling of the light loss through the lens!
Quote:


Does lens zoom affect PQ in any other way? Like loss of detail/colors or image distortion?

Only as I already stated: better focus/contrast at minimum zoom. You may begin to get some edge distortion at maximum zoom due to the properties of the lens. Remember: these are not "high-quality" lenses in these cheap projectors.
Quote:


if I have a room with 3 windows which will be covered with heavy drapes, can that be considered a dark room?

If you are tripping on the furniture with the lights out, it is a "dark room". The fanatics will also mask off the LEDs and luminescent displays to bring their theatres to absolute black. Again, the blackest "black" you will get from your PJ is that that exists when the lights are off!

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #16 of 24 Old 11-30-2006, 03:04 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by cavu View Post

No. Light loss over the distance we are talking about is of no consequence!No. Even most of the reviewers do not recognize the fact! Don't know about "most people".

Those looking for best PQ use minimum zoom (smallest image) because it provides better contrast and better focus.It's spelled out right in the projector specification but "most people" ( ) don't understand the significance: the Z5 lens F-stop varies as the zoom is adjusted from F2.0 to F3.0 ... a full F-stop ... which represents a halving/doubling of the light loss through the lens!Only as I already stated: better focus/contrast at minimum zoom. You may begin to get some edge distortion at maximum zoom due to the properties of the lens. Remember: these are not "high-quality" lenses in these cheap projectors.If you are tripping on the furniture with the lights out, it is a "dark room". The fanatics will also mask off the LEDs and luminescent displays to bring their theatres to absolute black. Again, the blackest "black" you will get from your PJ is that that exists when the lights are off!

But no matter what the lens zoom is set at, the closer your PJ is to your screen, the brighter it is going to be, right?

So if I have a dark room and set my projector at 106" and use no zoom, am I going to be able to see my screen?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #17 of 24 Old 11-30-2006, 03:05 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by cavu View Post

No. Light loss over the distance we are talking about is of no consequence!

What do you mean by this?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #18 of 24 Old 11-30-2006, 04:36 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

But no matter what the lens zoom is set at, the closer your PJ is to your screen, the brighter it is going to be, right?

It will be brighter per square inch of image. The number of lumens hitting the screen is constant for, a given zoom setting, regardless of the distance from the projector to the screen (for all intents and purposes) so a smaller image is brighter than a large image.
Quote:
So if I have a dark room and set my projector at 106" and use no zoom, am I going to be able to see my screen?

The "Dynamic" mode outputs 780 ANSI lumens which would equate to 22.7fL on a 106" 1.0 gain screen. Even at half the light, it would produce about 11.3fL (which is just about at the SMPTE standard 12fL). The "Living" mode produces up to 350 ANSI lumens which is marginal and the "Pure Cinema" mode at 180 ANSI would be too dim for that size of screen. Your option would be to get a screen with a gain of more than 1.0 to get the light level up again.

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #19 of 24 Old 11-30-2006, 04:38 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

What do you mean by this?

No-one ever computes the light loss over the small distance between the projector and the screen. The lumen output of the projector is assumed to reach the screen without any loss.

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
post #20 of 24 Old 11-30-2006, 05:44 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by cavu View Post

It will be brighter per square inch of image. The number of lumens hitting the screen is constant for, a given zoom setting, regardless of the distance from the projector to the screen (for all intents and purposes) so a smaller image is brighter than a large image.The "Dynamic" mode outputs 780 ANSI lumens which would equate to 22.7fL on a 106" 1.0 gain screen. Even at half the light, it would produce about 11.3fL (which is just about at the SMPTE standard 12fL). The "Living" mode produces up to 350 ANSI lumens which is marginal and the "Pure Cinema" mode at 180 ANSI would be too dim for that size of screen. Your option would be to get a screen with a gain of more than 1.0 to get the light level up again.

Wait a second...so if you increase zoom does that make the screen smaller or larger?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #21 of 24 Old 06-12-2007, 05:51 AM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by cavu View Post

It ought to be in the user guide or installation manual, either as a chart or spec.

I believe the Z5 has considerable lens shift available: a full screen height up/down and a half screen width left/right. This should make it very adaptable but I don't know the default axis offset.

does using lens shift distort the edges of the picture so that they are no longer square?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #22 of 24 Old 06-12-2007, 05:53 AM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
How would a projectors image quality (such as the Panasonic PT-AX100U, which I plan to buy) compare to something such as a Samsung DLP?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #23 of 24 Old 02-03-2008, 11:31 PM - Thread Starter
AVS Special Member
 
rocko1290's Avatar
 
Join Date: Jan 2006
Location: Allen, Texas
Posts: 2,926
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
When the manufacturer quotes a lumen output (such as 2000 lumens), is that number derived from the light output produced with the projector at full-zoom, half-zoom, or no zoom?

XBL: Rocko1290
PSN: Rocko1290
rocko1290 is offline  
post #24 of 24 Old 02-03-2008, 11:45 PM
AVS Special Member
 
cavu's Avatar
 
Join Date: Apr 2005
Location: CANADA
Posts: 6,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
Quote:
Originally Posted by rocko1290 View Post

is that number derived from the light output produced with the projector at full-zoom, half-zoom, or no zoom?

No one knows.

It will be the mode which provides the best spec !

"The greatest obstacle to discovery is not ignorance  it is the illusion of knowledge." - Daniel Boorstin
"Our lives begin to end the day we become silent about things that matter.
" - MLK

cavu is offline  
Reply Digital Projectors - Under $3,000 USD MSRP

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off