Please help clear up my Throw Ratio confusion.

p.booth · 21-05-2005, 12:19 PM

Please help clear up my Throw Ratio confusion.
I`m trying to decide on replacement for the Sony PJ thatI dropped.
I thought I understood the logistics of how to work the size of the screen along with the Throw ratio.
Having a Grandview motorised screen already,67" x38"with a diagonal of 77",,"I`ve tried a couple of online calculators giving the screen sizes to work out the required throw for preferred Pjs (H78+Sim 30h) only to find putting in the diagonal or the width of screen gives a throw ratio and changes the height and diagonal etc.
Ihope i`m making myself clear.

In other words my size of screen isn`t matched with the size of picture the calculator gives for the Throw ratio.
Is this right or am I missing something .I wouldn`t want to have to buy another screen .Anyone throw some light on my confusion.

Gary Lightfoot · 21-05-2005, 12:52 PM

You have to tick the little bullet hole that says throw range rather than diagonal range - it's on the left hand side in the oblong box at the top left of the calculator. You then use the slider in that box to get the figures for the max of the range - 8'9" to 12'1" for your screen.

Gary.

p.booth · 21-05-2005, 2:11 PM

Thanks Gary.
Is the H79 the US version of the H78 ie do they have the same throw ratio??. It lists the H79 but no H78. Thanks Peter.

Gary Lightfoot · 21-05-2005, 2:17 PM

The H79 uses the DC3 chip so absorbs more light when the mirrors aren't reflecting, and has no dimple so is more reflective and this equates to being far brighter and having more contrast. The H79 is brighter in low lumen mode than the H77 was in high mode. It also achives 2900:1 at D65 which is more than 600:1 better than the H77 could attain.

It's not going to be released over her though, so we'll have to make do with the H78 which is an improvement over ther H77 but not as good as the H79.

Gary.