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UST projector for big screen


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Hello everybody!

I am looking for an advice and I hope some of you guys has the experience or possibility to try my scenario:

I need a big screen around 5 meters diagonal (16' = 5 meters) from shortest distance possible -> an UST projector.

Projector which should also fulfill:

- easy to carry - 5kg (10lb) max

- compact shape (no fixed mirror if possible)

- 3000 lumen and more

- throw ratio around 0.3

- price around 1000€

- image correction allowing shifting the image as close as possible to the floor when projecting from the floor


What doesn't matter:

- no need for super projection quality - simple graphics will be projected

- no need for 10 000 lumen projector - room is darkened


Today there is may projectors which could fit, BUT most of them have in specifications MAXIMAL screen size around 100". What does this mean?

Does it mean, that I won't be able to focus the image if I move the projector further from the wall? Or why is this limitation in the specifications?


The only model I found which according to specs allows bigger screen - Benq MW870UST (circa 1000€) - is not sold in Europe http://www.bigscreenforums.com/images/smilies/frown.gif.


So the question is: Can I use any other UST projector and disregard the maximum screen size specification and just install the projector far enough from the wall in order to get the big screen? Or I need to find and use only a projector which declares the big screen (circa 16') in specifications?


Thank you for your opinions!



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Having probably had as much ust experience as anyone, heres a few pointers... the maufacturers specs are misleading with regard to maximum screen sizes. usually the simply refer to the maximum achievable screen size using the supplied wall mount. Ive personally tested units from hitachi, nec, Panasonic and optoma and they all work in the region of 5 - 6m and beyond even though the specs suggest they don't. Any Ultra short throw will don't project any where near the floor from the floor, and if you tilt it you just get a triangle. without doing the maths, id guess that a 5m diagonal image will start at least 1m from the floor, if you need to go to the floor, you need to fly the unit. You will however be able to project 5m from around 1.5m away which is fairly remarkable...


Id suggest the hitachi cpa352 which has a mirror that folds away and is remarkable small and light and should come in around your budget. It also has "perfect fit" geometry correction which will make the lineup onto a large surface easier. We have supplied rather a lot of these into theatres in recent times and generally people love the fact that they can do impossibly large images from no distance away. They are also actually pretty bright, something you cant judge from the printed specs...

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Hello Journeyman!

thank you for your precious advices - this is exactly what I was looking for! there is not many people working with USTs who could compare them as you can.

the Hitachi is looking good. But looks like discounted model - I've found it only in 1 shop and the price is 1350E. I'll check out their current models.


the gap between the floor and the image is not so good news. projection from above would significantly decrees the setup flexibility and easy mount/transport idea. would vertical image shift or vertical keystone help in this case? do you have any experience? I would welcome to lower the gap to less than 0.5 meter.

otherwise I was thinking of tilting the projector and transforming the image shape at the image source side, but this would greatly reduce the usable projection area and waste the lumens at the same time.

thus vertical image shift and keystone could help. but the maximum keystone I've found at UST was about 15 degrees - how this works in practice? how is the keystone calculated - what means the 15 degrees?


thanks for help!



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I'd Imagine (and this is more of an educated guess, so don't take it as fact) because the UST projectors usually have to shoot back over themselves its the body being in the way which stops them getting low to the floor. It might also be to do with the way the reflector works...
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its simple optics, if you tilt a unit forwards, the distance to the top of the screen becomes shorter and the image starts becoming progressively triangular. you can combat this by keystone correcting it and counteracting the decrease in the size by moving the unit back, which lifts it, so you tilt it down, keystone it, move it back....the image lifts, etc etc. basically the relationship between a projector and screen is a fixed one, the only way to decrease the distance between the bottom of the screen and the floor is to tilt the projector AND screen forward, this works, but obviously at some point the screens going to be tilted further forward than is acceptable.


You are correct in trying to avoid flying the unit if you can as you have to provide micro adjustments a long way up on a swinging bar which can be less than fun, but its absolutely impossible to project to the floor from the floor with a ust, and I speak with more than a little experience, by any other means.


the actual reason that a ust has a fixed upward shift is simple down to their primary use which is to project onto a whiteboard, if the unit didn't have the shift, you would be banging your head on it as you used the whiteboard. that's why short throw units have similar shift as well.


hitachi units are very much available and we sell a fair few the current range is here -http://www.hitachidigitalmedia.com/product.do?actionName=listgroups&pt=6&pg=86




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Hello guys!


2 AHYoung: looking at Hitachi CP-A352WNM optical specifications. What this "Keystone: Fixed, 5.2:-1 upward shift, Normal at +68.3° projection angle" mean?


I understood:

Fixed - there is no keystone correction

5.2:-1 - no idea

upward shift - you can shift the image only upwards (not down). Since the UST is designed to fly above a whiteboard, this will shift the image up = towards the projector?

normal at +68.3° projection angle - in projector on the floor scenario, this is the angle between image center and floor, measured at the projector mirror?


I hope you can understand my description. please correct me where I am wrong.

I guess the problem with keystone and UST is that the projection angle is so far from being perpendicular to projection plane that a small change of this angle would result in sever keystone :(.



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  • 1 month later...

We use a local company, Popcorn Media (www.popcornmedia.co.uk) who carry a number of UST projectors. Certainly one of these will project at floor level without keystone issues etc. I'm sure they will help if they can, either rental or sales or advice.


Good luck...

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