[garliadr]

Hey all, moving into a new house in a couple of weeks and had planned to get a plasma but am now looking at a projector. The room size that I am planning this for is about 15' x 11', the screen at one end with the projector at the other (11' away from each other) with the main viewing position probably 9' away from the screen. Does this sound Ok? I ask because I am a bit of a newbie at projectors. Also how far down does a screens casing hang as it is going to be mounted above a set of patio doors that give access to a conservatory (with blackout blinds over natch
).

[JohnS]

The screen casing is about 4*4 inches so probably no worries about getting in the way of the doors.

AS for sitting 9ft away and projecting 11 ft, its just about image size really, you wont be able to go too big and make sure you select a pj with a short throw.

[garliadr]

I am looking at either Panasonic AE100, Sony HS10 or Sanyo VPL10(?). Are most of these short-throw? I did demo a Sanyo at a local Sevenoaks and from 9ft away it looked pretty damm good!

[Gary Lightfoot]

If you go for LCD, you should sit approx 2 x screen width away, otherwise you'll see screen door which will probably spoil the image. (IE sit 10 feet away from a 5ft wide screen).

Gary.

[JohnS]

ae100 is short throw, hs10 isn't, not sure about the sanyo z1, shortish I think. ae300 should be short and might be worth considering.

To follow on from what Gary said, the higher the res of the pj for the same size image, the more you can get away with sitting nearer to it.

Originally posted by Gary Lightfoot
If you go for LCD, you should sit approx 2 x screen width away, otherwise you'll see screen door which will probably spoil the image.

Not with the HS10

The AE300's smoothscreen technology apparently also makes it good for < 1.5x screen width viewing. Haven't seen one though, so can't confirm/deny.

The AE300 is exactly the same as the AE100 in terms of throw ratio. The HS10, as stated, is a long throw PJ.

You need to do some simple maths.

Rules to follow:

1. Try not to have your seating distance nearer than 1.5 * screen width. My personal setup is 180cm wide screen viewed from 280cm.

2. From your seating position, the angle to the edge of the screen should not be more than 30 degrees. Simple trigonometry can calculate this EASILY eg:

Angle = tan-1 (w / 2d) where w = screenwidth in cm and d=distance to screen in cm.
This angle should not be more than 30 degrees otherwise you will be moving your head around to see the picture.

3. Find out the throw ratio of the projector. This will generally allow you to calculate the image width for any given distance from the projector to the screen. Some throw ratios refer to image diagonal. If this is the case you will obviously need to calculate the diagonal of your screen.

This is very simple. Use Pythagoras ie:

Diagonal = SQRT ( (width * width) + (height * height) )

Apologies to mathematicians out there but this was the simplest way I could think of of expressing it....

If you know the width of the screen and the aspect ratio you can work out the height eg:

Screen width = 180 cm
aspect = 16:9
height = 180 * 9/16 = 102cm

The idea of the throw ratio is so you can draw a diagram, having your proposed screen on it and proposed projector siting. Then make sure the projector is actually capable of projecting the image that you plan onto the screen at the correct size.

In addition, if you want to get more technical, you can then work out the illumination level of the screen if you work out it's surface area and then you can tell how "bright" the image is going to be. This is handy in choosing a projector - you don't need a 2000 lumen light cannon to satisfactorily illuminate a 80" picture. However if you plan a 120" picture than you will do.

At the end of the day, the whole issue is a bit more complex than just finger-in-the air guesses. Most people just guess and trust and hope to luck and a bit of experimentation. If you don't want to do that, then you're going to need to do some maths otherwise you might find out that your proposed projector siting, image size or viewing angle is not what you thought it might be.

Hope this helps
J

[garliadr]

gulp!!

thanx john, good reply.

Spoke to a chap today at my local sevenoaks who informed me that with my sized room, a sanyo plvz1 with a 5ft screen should be pukka. I will work it all out before i buy tho.