[Justin Kerns]

I'm helping a friend build his HT and he has a Pearl & 2.35 Carada 1.4 gain screen. He is doing poor man's CIH and zooming & shifting between 2.35 & 16:9. We've run into a problem and I'm stumped - was hoping AVS forums can help!


His setup-

Screen size: 109" wide x 46" tall

Throw: just over 12' (12.17' to be exact)

Mount: ceiling, aligned with top of screen


The problem-

When zooming out for 2.35 to maximize width and fill the screen, the image won't quite get large enough. It stops with about 1" on all sides of unused screen area.


According to my math and pages 14 & 15 of the Pearl's owner's manual, the Pearl should be able to project this image size at about 11.25' throw, which is almost a foot less throw than he has. But the zoom is bottoming out at about 107" width.


We checked the "Blanking" menu option and it's set to 0. Display mode is "Normal".


So, I admit I am not an expert, but I tried searching and am trying to understand the specs and it seems like this should be working. Any ideas?


Help is *greatly* appreciated!


Thanks!

 

[Jason Turk]

You are just missing it. At 12.17' on a 109" wide screen...the throw is 1.34...the Sony minimum is 1.4x.


Any chance you can move it slightly?

 

[Justin Kerns]

Jason -


First of all thank you for the reply.


I'm confused - the tables Sony provides (when interpolated for 109" screen width) indicate a minimum throw of 11.74'. This equates to a minimum zoom of 1.29x, not 1.4x.


What gives?


And no, it will be extremely difficult to move the PJ. There is a steel beam & ductwork immediately behind it.

 

[Jason Turk]

Yeah that is incorrect. I don't recall, but I think that it is based on diagonal, not width as you are figuring.


I could be wrong...

 

[Justin Kerns]

Incorrect? Sheesh that is unfortunate!


Still, the Sony table doesn't support the 1.4x minimum, even if the screen size should be diag instead of width (which is an excellent point you make - duh!). For example, Sony shows min. throw of 147" for a 120" screen. This equates to 1.23x zoom. Huh?


Here is the manual in case you want to see for yourself:
http://www.justinkerns.com/avs/Sony ...ers Manual.pdf

 

[Erik Garci]



Quote:
Originally Posted by Justin Kerns /forum/post/14247022


Still, the Sony table doesn't support the 1.4x minimum, even if the screen size should be diag instead of width (which is an excellent point you make - duh!). For example, Sony shows min. throw of 147" for a 120" screen. This equates to 1.23x zoom. Huh?

A 120"-diagonal 16:9 screen is 104.6" W by 58.8" H. So the minimum throw ratio is 1.4 times the width, since 147" / 104.6" = 1.4.

 

[Jason Turk]

There you go.

Unfortunately manufacturers don't always remain consistent on calculations. Though the lens is almost always based on width, in this case Sony decided to put diagonal in the manual. Not a very good idea.

 

[Justin Kerns]

Got it - thanks for the help. Consistency in their information is one thing, but Sony doesn't say anywhere in the manual whether it is width or diagonal. It just says "screen size". Sloppy!

 

[Jason Turk]

Yeah it isn't a great manual unfortunately. Oh well...you know now!