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Discussion Starter · #1 ·
My current plan for a theater I'm building is to use a Runco VX-5000ci (1500 lumens) DLP projector with a 120" (width) Stewart Firehawk screen.


My concern is hotspots. My questions are,


a) Should I be concerned at all? A lot?


b) I believe I've read that hotspots are worse when you use a short throw. The Runco is very flexible. Any thoughts on how far back to go? Any drawbacks to going further back?


Thanks alot.
 

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I've got a 100" FireHawk with an InFocus 7200 at 15'. The center of the screen is somewhat brighter than the edges but not so much that I ever notice in watching actual video. I can see it on a white screen. I'm not sure how much is from the screen and how much is the PJ. In any case it is not a problem for me.


With regards to throw distance, Stewart says the longer the better (for hotspots). You want all the light hitting the screen as close to perpendicular as possible. So unless there is some issue with your optics at long throws I would say go back as far as you can.
 

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Discussion Starter · #3 ·
Quote:
Originally posted by dhp
I've got a 100" FireHawk with an InFocus 7200 at 15'. The center of the screen is somewhat brighter than the edges but not so much that I ever notice in watching actual video. I can see it on a white screen. I'm not sure how much is from the screen and how much is the PJ. In any case it is not a problem for me.


With regards to throw distance, Stewart says the longer the better (for hotspots). You want all the light hitting the screen as close to perpendicular as possible. So unless there is some issue with your optics at long throws I would say go back as far as you can.
The Runco says it can go really far back. I'm just wondering, in general, if you lose anything (e.g., brightness) with long throws?


Thanks for the help.
 

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FWIW, I attended the Fixed Pixel Display seminar two weeks ago. The "reference" theater at the facility had double stacked Runcos (don't know the model) at the back of the room. At the end of the seminar, they fired up the Runcos and dropped down a 10-ft wide firehawk and showed some D-theater material. It looked fantastic.


Since I am considering the firehawk, I took note of my position. Since the room was crowded, I ended up about 1X screen width back and about 1 ft outside the screen (like I said, pretty crowded). This is much worse than any seat in my future theater, so I considered it a good test.


As for the picture, I saw no hotspotting, but I could clearly see the drop off in brightness across the screen, due to the narrow viewing cone.

The good news is that when I watched the movie, it did not bother me at all. So for me, it is a non-issue since my theater will not have a seat that bad.


As a side note, the Runcos were ceiling-mounted as far back as they could go. I don't know if they had a special lens or not, but I would estimate they were about 2X back.


Art
 

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A long throw should not affect brightness. In either case (long or short) you are taking all the lumens your projector can produce and putting them on the same screen with the same area. In your case you have a screen that is about 56 ft sq (if my math is correct) and a 1500 lumen projector and a screen with 1.3 gain. Your brightness should be:


1500/56 *1.3 = 35 ft candles. Throw does not enter into the equation.


35 ft candles is pretty bright but your projector output will drop as the lamp ages. If it is too bright for your tastes you can always add a Neutral Density filter to cut the output.
 

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Quote:
Originally posted by Daniel Hutnicki
Hey Vandelay, I was there also. Did you come on Saturday or Sunday and if you came on Saturday, what do you look like
I was there on Saturday. I was wearing jeans and black polo shirt, I think. My name tag said "Randy" on it since A. Vandelay is just a Seinfeld thing I've been using for a long time. During the lunch demo, I was the one who tripped over Gary's foot in the dark and almost went flying through the Stewart rear projection screen!


All in all, the seminar was great, and seeing the WSR setup was worth the price of admission alone!


Art
 

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I have a Sharp 10K at 18 feet and a 110" Firehawk. I have looked for, but have not seen any hot spots with any display.
 

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I use a 100" diagonal Firehawk with my projector about 18' form the screen. I see no evidence of any hotspot. Of course I have a Sim2 300 Plus and many critics would say it isn't bright enough to produce a hot spot! That's a joke son!


Tom
 

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Discussion Starter · #10 ·
Quote:
Originally posted by tomrhyne
I use a 100" diagonal Firehawk with my projector about 18' form the screen. I see no evidence of any hotspot. Of course I have a Sim2 300 Plus and many critics would say it isn't bright enough to produce a hot spot! That's a joke son!


Tom
 

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I have a 133" Firehawk and I've never seen any evidence of hot spots either. I believe Stewart guarantees against them (will exchange screen).


IMO the Firehawk would be an excellent mate for your Runco.
 

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The projectors at the FPD seminar were Runco VX1000ci's . They were at 2x screen width.


Next FPD seminar will be in Chicago May 17th.
 

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Quote:
Originally posted by dhp
I've got a 100" FireHawk with an InFocus 7200 at 15'. The center of the screen is somewhat brighter than the edges but not so much that I ever notice in watching actual video. I can see it on a white screen. I'm not sure how much is from the screen and how much is the PJ. In any case it is not a problem for me.


With regards to throw distance, Stewart says the longer the better (for hotspots). You want all the light hitting the screen as close to perpendicular as possible. So unless there is some issue with your optics at long throws I would say go back as far as you can.
Yep,


Use as long a throw as possible with the Firehawk.


-Mr. Wigggles
 

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Quote:
Originally posted by thegratingone
The Runco says it can go really far back. I'm just wondering, in general, if you lose anything (e.g., brightness) with long throws?
You don't lose anything with a long throw.


In fact - there are reasons to prefer long throws.


With a long throw - the divergence angle of the beam is less than with a short throw. Optically, this means that you are

in the most linear regime of your optics - you're asking the optics to bend the light less - hence less optical distortion

which all optical components, like lenses; introduce.
 

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As a general rule of thumb Stewart says to try and be about 2x screen width to minimize hotspotting. You can likely have decent results from 1.5x but 2x seems to be the goal.
 

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Discussion Starter · #16 ·
Quote:
Originally posted by lovingdvd
As a general rule of thumb Stewart says to try and be about 2x screen width to minimize hotspotting. You can likely have decent results from 1.5x but 2x seems to be the goal.


You mean throw not seating distance right?
 

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Yes, throw.


I agree that long throws are the way to go, for the two reasons mentioned:


- It reduces hotspotting since the light comes in more perpendicular

- It uses the most linear part of the lense's optics (the center)


-Tom
 

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Discussion Starter · #18 ·
Quote:
Originally posted by PerfKnee
Yes, throw.


I agree that long throws are the way to go, for the two reasons mentioned:


- It reduces hotspotting since the light comes in more perpendicular

- It uses the most linear part of the lense's optics (the center)


-Tom


Thanks. Do you know if throw length matters for whether you see the rainbow effect?
 
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