Disadvantages of long throw projection ?

[jeremias]

I'm faced with a situation in which it isn't possible to mount a projector on the ceiling of our new film society venue, but it is possible to project from the lighting booth at the back of the hall. But this is 18m back from the screen ! We have inherited a powerful XGA projector with a suitable long-throw lens, but I'd appreciate any help in understanding the disadvantages of projecting over such a distance. We will have total blackout (although the two exit lights in the hall are horribly bright).
Are we going to face horrible consequences if we try to project over such a long distance ?

PS. we have an old (but good) Sony VPL-FX52 5000 lumen projector and long-throw lens.

Thanks

 

[sound idea]

Back in the day I have projected films from both long and short throws and experienced no real issues with either.
If the atmosphere is very dusty you might get some loss of brightness in the image but it would be a second order effect. Also if you have to project through glass you'll get some light loss due to the transmission index of the glass.
With a longer throw the physical stability of the projector becomes more critical as small movements will cause a large movement of the screen image. If using a table or stand make sure it is secure - in particular make sure the floor is sound as people walking by could cause the image to wobble.
My 2p, good luck.

 

[jeremias]

Back in the day I have projected films from both long and short throws and experienced no real issues with either.
If the atmosphere is very dusty you might get some loss of brightness in the image but it would be a second order effect. Also if you have to project through glass you'll get some light loss due to the transmission index of the glass.
With a longer throw the physical stability of the projector becomes more critical as small movements will cause a large movement of the screen image. If using a table or stand make sure it is secure - in particular make sure the floor is sound as people walking by could cause the image to wobble.
My 2p, good luck.

Thanks. Good advice.