I just tried to take a measurement while I was down at the house but it's not easy with one pair of hands so I gave up. It sounds like you're suggesting there that there is a fixed scale of screen size versus distance from the projector. Is this not variable from the projector?

Yes, they are basically a fixed screen size vs distance, the positioning distance and screen size does vary from PJ to PJ.

Some come with a zoom, but it's only adjusts a few inches not feet.

So would that make getting a 1080 PJ a better idea than a 720 one because of the distance or is that irrelevant?

Resolution is more to do with seating distance not PJ/screen distance - As you are going to be sat 4/5's of the distance from the screen I would say either resolution would do, basically because you will be sat well outside the seating distance for each resolution.

The light from a projector spreads out like a cone, you can narrow the cone a bit using the zoom...

But only a bit unless you spend big money on higher end projectors with a large zoom range.

The "narrow end" of the cone is at the projector, the wide end gets wider the further away the screen is. The zoom function narrows/widens the cone.

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I have just looked up the size of the image at 26ft for the Optoma HD230x and it's 14feet wide minimum. Up to 17feet wide using the zoom. The zoom is 1.2:1 on this model.

The image brightness gets dimmer the bigger the screen. I'm guessing at 26ft of course, but a screen 14" wide is quite big (but impressive as anything).

You will need to watch this in the pitch dark I think, 14ft / 17ft is a large area of screen.

If the distance is, say, 20ft then the width will be about 11feet (up to about 13ft with the zoom)



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"Light's On" viewing is just an indoors thing, you can have the lights on as long as there is very little direct light on the screen. This cannot apply to outdoors and there is no way you can use a projector outdoors during the daytime.

Maybe when the sun is very low in the sky, then maybe it will be just about watchable. Never tried so not sure.

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http://www.optoma.co.uk/projectordet...ment&PC=HD230X

page 16 shows distances and screen sizes.

http://www.projectorcentral.com/Opto...ulator-pro.htm

This is a distance calculator for a similar model (Optoma HD23)

Same zoom range/ similar brightness. It might not be exactly identical in distance/size but it's a good guide.


I think 20ft distance is going to be the limit for reasonable brightness, giving a screen width of about 11feet (3.3m)

Will the "cone" clear the french doors though?

This is what a 14ft wide screen is like (indoors):

http://www.avsforum.com/t/1316865/14...-screen-w-pics

One solution to narrow the cone is a lens converter.


These were designed for camcorders when they did not have very much of zoom range, you can often find them on Ebay for a few quid.

To narrow the cone you need a tele convertor. It sounds strange to use a "tele" lens (doesn't that make things bigger?) The answer is no, a tele lens narrows the field of view.


An Olympus "TCON 14" is good enough. It might not work however! The lens on the Optoma HD230x is recessed somewhat.

The TCON 1.4X tele lens will narrow the cone by about 30%. So a screen of 14ft will instead be around 10ft (at 26ft distance)

The help here is great, I'll have to work out the measurements to see if its a doable project. One thing I've not looked at is the cost of the screen, how much would a 14' one cost?

14feet wide is probably out of the question as a portable thing, it would have to be a permanent installation.

Or painted onto the wall. Plastering the wall first.

14feet is really vast. A domestic projector might not be bright enough to fill it.

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You can get pull-down 120" diagonal screens on Ebay for about £120. 150" diagonal for less than £200
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I don't see the idea of having a projector mounted on a wall opposite the french windows as practical.

But there isn't a problem projecting through glass, the light loss is very little. So maybe have a little table behind the french windows with a lower shelf for the projector?

That would really cut the projection distance down to a manageable number.

I don't want to come over like the merchant of doom. After all, it's your money. However, some of us here have considerable experience in very large screen projection, and getting some info from the horse's mouth could save you a lot of time and cash.

14ft screen is unrealistic unless you have won the lottery...

1) It'll just take far too much light power to illuminate sufficiently against ambient light to make it worthwhile
2) it's a massive sail. Any small gust of wind will cause you problems
3) that acreage of screen will be very heavy. The roller mech will be disproportionally bigger and heavier than a convention 8ft screen.
4) it'll be too big and heavy for a temporary install; and yet too fragile (not weather/frost prrof) for permanent outdoor install... Rock vs Hard Place

The idea of some cheap telephoto converter lens doesn't float. Cheap glass means loss of light power and, more seriously, lot's of image distortion. You'll get colour fringing (chromatic aberration) and loss of focus at the edges of the image. See this YouTube video. Scroll forward to 2:00 to see the before and after.

If you want to do ourdoor projection on the cheap then go for the painted white wall - look at paint options from the DIY screens section of AVForums and go for something as bright white as possible. Then buy as bright a projector as you can possible afford. Rig up a table and some long extension leads. Park the projector in front of the wall. When finished, just bring the projector back indoors.

Any other solution requires either a significantly larger budget than the Optoma you've been looking at, and it also involves technical hurdles that will be difficult (read: expensive) to overcome.

Teleconvertors do work because I've done it.

The important thing is to review the specific lens (in it's use for digital cameras)

The Olympus TCON14 reviewed well for focus/chromatic ab/contrast so I tried it and it worked well. Very reasonable price as well.

TCON-14b is the better version.