Image Size to large for FTIR surface. 
Posted: 15 July 2008 12:57 PM   [ Ignore ]
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So I didn’t really take into account the specifications of the projector I have to use when planning my table.  Ooops.

I have access to a Panasonic PT-LB10NTU projector which has the following specs:
Brightness (Lumens) :  2000 ANSI
Contrast (Full On/Off) :  500:1
Size (inches) (HxWxD) :  2.6 x 11.7 x 8.3
Std. Lens:  Focus:
Manual
Zoom:  Manual, 1.20:1
Throw Dist (feet) :  4.6 - 29.5
Image Size (inches) :  40.0 - 300.0

My table is approximately 28.75 inches diagonal.

So do I need to find a projector that supports a smaller screen size?  Is there anyway around that?  I hate to have to spend money on a projector when I have a free one available.

Thanks.

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Posted: 15 July 2008 01:10 PM   [ Ignore ]   [ # 1 ]
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Do you have a zoom option so you can make it smaller?

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Posted: 15 July 2008 01:21 PM   [ Ignore ]   [ # 2 ]
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There is a zoom option listed above:  1.2:1… but wouldn’t zoom do exactly the opposite of what I want?

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Posted: 15 July 2008 01:35 PM   [ Ignore ]   [ # 3 ]
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Some will let you zoom out. Also, you can always position the projector so it is closer to the surface thus making the image smaller).

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Posted: 15 July 2008 01:40 PM   [ Ignore ]   [ # 4 ]
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I wasn’t sure if since it listed the smallest image size at 40 inches if that meant that if I moved it closer it would be out of focus or unusable in some other way… I was hoping it would be okay, but I figured they must list a minimum size on their specs for some reason!?!?  Unless that is just to provide a reference point for the Throw Distance?

I could have sworn I read somewhere that this wasn’t the case though.

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Posted: 15 July 2008 02:40 PM   [ Ignore ]   [ # 5 ]
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I guess I should have been more thorough with the search feature.

Here is a thread that sort of answers the question:
http://nuigroup.com/forums/viewthread/719/

The very last post on the first page states that using size smaller than what the manufacturer lists as the minimum size will result in blurring, but it didn’t become noticeable until the size was a good bit smaller than the specified minimum size.

His example was minimum 47.6 inches wasn’t bad until around 30 inches… Mine is 40 inches minimum, so hopefully I can get to 28.75 without too much blur.  I guess I really should have just got my hands on the projector I will be using and given it a try myself!

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Posted: 15 July 2008 03:04 PM   [ Ignore ]   [ # 6 ]
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I’m having the opposide problem with my Panasonic AX-100, getting the image smaller and focused at 1,5m isn’t really the problem, i cant get a bigger picture with the distance i have.
Just place some paper on your surface and try it out, see how it works out.... According to panasonic’s specs i should have been able to get a bigger picture then i’m currently getting, and smaller is easy smile

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Posted: 15 July 2008 03:12 PM   [ Ignore ]   [ # 7 ]
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Thanks for the info!  I will be using a projector loaned to me from work, so I haven’t really had a chance to try it out yet.  I really should do that though while waiting on my camera to come in.  (Final piece I am waiting on before I finish construction of the screen.  Could finish now, but want to wait and test the current setup with LEDs to make sure it is OK before finishing.)

I did fire up the projector calculator at:
http://www.projectorcentral.com/Panasonic-PT-LB10NTU-projection-calculator-pro.htm

It tells me I need a throw distance of 3’3”, which to me sounds about ideal.  I might can get this going without needing to even use any mirrors!

I’m surprised you are having issues with the maximum distance.  I would have thought that they would be pretty accurate about that setting since it is one that most people would attempt to push the limit on.  I don’t really know much about projectors as I have never even owned one, so I don’t have any helpful advice for you.  Sorry.  Thanks again for the info though.

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