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Backyard Theater - Outdoor Movies

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Author Topic: Rear Projection and Brightness  (Read 6087 times)
1502tuley
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« on: August 30, 2011, 09:56:11 am »

Hello all.   This is my first post, but I have been a board reader for a long time.   I have been reading all the posts every day for over six months now.  I am addicted!   I want to thank everyone for all of the great information you have given me.  This place is great.   

OK, here's my question.   I am now staring my first outdoor theater party in the face.  I have a brand new BenQ w600+ that's still sitting in the box.   I bought 3 yards of trapeze, a steel pipe frame and some fabric clips that I intend on using to create a rear projection screen (I have to do rear projection because the distance I would have to throw for front projection is too long).
   
I would like to have a 12' X 6'-9" screen, but that would leave me with 16 lumen at the screen (at least that is what the calculator on projector central tells me).    Is that going to be bright enough in a rear projection application if it is a completely dark night, with very little ambient light?   I could have a smaller screen, but want to go as large as I can without sacrificing too much in the way of picture quality.  Any information from you experienced guys/gals would be greatly appreciated.
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Sparge
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« Reply #1 on: August 31, 2011, 01:39:59 am »

One does lose brightness when rear projecting.  However, even without doing the math I'd say you have no worries with a 2600 lumen projector on a 12' screen!

Tip 1:  Position the projector just below the screen to prevent hot spotting (seeing the projector beam from the front).  You'll also want some form of dark curtain at the bottom of the screen to block the audience's view of the projector from under the screen.

Tip 2:  Do a trial run in advance of your party.  It's amazing all the show-stoppers (things you didn't think about) that can turn up when you first get started doing BYT.

-Sparge-
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1502tuley
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« Reply #2 on: August 31, 2011, 09:16:05 am »

Thanks Sparge.

I was hoping I would have enough brightness.  I kind of put the cart in front of the horse by not asking that question before buying the projector.   I guess I got lucky and bought one that will work with my required application. 

I had forgotten about putting the dark skirt on the bottom of the screen to block the hot spot.   Thanks for the reminder.   I guess I will be going to Joann’s this afternoon to pick up some fabric.

I'm trying to go all out on with this first party.   We are going with a "Dive in Movie" theme where we will be showing the movie at one end of the pool.   I was thinking about showing Jaws as one of the shows.   We bought a popcorn machine on a cart (kids can't wait to use it), a ton of burger and hot dog stuff and a boat load of nachos to round out the party.   I'm not sure what we will be serving in terms of drinks.    I have been eyeing one of those Margaretville margarita machines, but the better half has been putting the brakes on that purchase.   

My only fear at this point is the distance I will have to run the extension cords to reach my PJ and tuner.   That run will be approximately 150'.    I will be using one 100' cord and one 50' cord, both 14 gauge.   Is there any reason this long of a run would cause me problems?   I hope not.    My wife will literally kill me if this project ends up in us having to pay to have a permanent electrical line run to the back side of the yard.   
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Sparge
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« Reply #3 on: August 31, 2011, 12:48:21 pm »

My only fear at this point is the distance I will have to run the extension cords to reach my PJ and tuner.   That run will be approximately 150'.    I will be using one 100' cord and one 50' cord, both 14 gauge.   Is there any reason this long of a run would cause me problems?   I hope not.    My wife will literally kill me if this project ends up in us having to pay to have a permanent electrical line run to the back side of the yard.

If that 150' of cord only powers the PJ and sound system you should be fine.  Keep things like the popcorn machine on a different circuit if possible.  Also, since this is around a pool you should invest in a GFCI adapter.  You'll want the GFCI as close to the source of power as possible (not on the end near the PJ).

-Sparge-
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1502tuley
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« Reply #4 on: August 31, 2011, 01:04:34 pm »


My only fear at this point is the distance I will have to run the extension cords to reach my PJ and tuner.   That run will be approximately 150'.    I will be using one 100' cord and one 50' cord, both 14 gauge.   Is there any reason this long of a run would cause me problems?   I hope not.    My wife will literally kill me if this project ends up in us having to pay to have a permanent electrical line run to the back side of the yard.

If that 150' of cord only powers the PJ and sound system you should be fine.  Keep things like the popcorn machine on a different circuit if possible.  Also, since this is around a pool you should invest in a GFCI adapter.  You'll want the GFCI as close to the source of power as possible (not on the end near the PJ).

-Sparge-
Good deal.   The PJ and receiver will be the only two things on that circuit, and it is a GFCI plug at the outlet.  Electricity is one thing I won’t take any changes with.   It will always be GFCI protected at the source, and the cord will always be run on the back side of the fence (away from the pool) to eliminate any chance of it getting anywhere near the pool.   I will run the popcorn machine off of a different outlet.   
Thanks Sparge.
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KrazyTrain
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« Reply #5 on: September 02, 2011, 05:31:48 pm »

I have been rear projecting on Trapeze movie fabric for a few years no with no problems at all...as long as your projector has that kind of light output, you will never have a problem...
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1502tuley
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« Reply #6 on: September 07, 2011, 09:57:06 am »

Well the weekend was a mix of greatness and disappointment.   We had two movie nights for two different parties.   The first night was fantastic.   The PJ was bight and clear and the trapeze was fantastic.   I did have some issues with the image on the PJ shaking every now and then, but I think that was due to a faulty s-video cable (or at least that is what everyone is telling me). 

The disappointment came the next morning.   I left the screen up over night.   Well a front came through after we went to bed and proceeded to blow it down (along with everything else in my yard).    It snapped one of the frame's pipes in half at a joint (an 3/4" iron pipe no less).  It snapped the threaded part right off the end of the pipe.    The wind was so strong it pulled the anchors to the guide wires  up I had screwed into the ground.   I had been using the cork screw things that you screw into the ground and attach a dog chain to.  Those things were 1.5' into the ground and got ripped up like they were nothing.   It blew all of our pool chairs over and blew our table’s umbrella out of its base and across the yard.   It was a freak thing.

Luckily I had built two different screens and frames, I had to use my smaller BOC screen (10’ X 5.5’) for the second party.  I had to put that screen in the middle of the yard instead of at the edge of the pool due to my PJ’s throw ratio (shooting over the pool generated an image too large for the smaller screen) so that was kind of a bummer since it was a dive in movie theme.    It still went well though, it just wasn’t as nice as the first night on the larger screen. 

All things considered I was very  happy.  The first showing was great, the second on the smaller screen was not quite as good by comparison, but still tons of fun.    I was able to repair the larger screen on Monday, so we are back in business for next weekend.   

Related Question:   When the Trapeze screen blew down it got really dirty.    How should I clean it?   Can I throw it into the washing machine on gentle, or is it a hand wash only item?



« Last Edit: September 07, 2011, 10:36:40 am by 1502tuley » Logged
KrazyTrain
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« Reply #7 on: September 07, 2011, 11:08:54 am »

Well the weekend was a mix of greatness and disappointment.   We had two movie nights for two different parties.   The first night was fantastic.   The PJ was bight and clear and the trapeze was fantastic.   I did have some issues with the image on the PJ shaking every now and then, but I think that was due to a faulty s-video cable (or at least that is what everyone is telling me). 

The disappointment came the next morning.   I left the screen up over night.   Well a front came through after we went to bed and proceeded to blow it down (along with everything else in my yard).    It snapped one of the frame's pipes in half at a joint (an 3/4" iron pipe no less).  It snapped the threaded part right off the end of the pipe.    The wind was so strong it pulled the anchors to the guide wires  up I had screwed into the ground.   I had been using the cork screw things that you screw into the ground and attach a dog chain to.  Those things were 1.5' into the ground and got ripped up like they were nothing.   It blew all of our pool chairs over and blew our table’s umbrella out of its base and across the yard.   It was a freak thing.

Luckily I had built two different screens and frames, I had to use my smaller BOC screen (10’ X 5.5’) for the second party.  I had to put that screen in the middle of the yard instead of at the edge of the pool due to my PJ’s throw ratio (shooting over the pool generated an image too large for the smaller screen) so that was kind of a bummer since it was a dive in movie theme.    It still went well though, it just wasn’t as nice as the first night on the larger screen. 

All things considered I was very  happy.  The first showing was great, the second on the smaller screen was not quite as good by comparison, but still tons of fun.    I was able to repair the larger screen on Monday, so we are back in business for next weekend.   

Related Question:   When the Trapeze screen blew down it got really dirty.    How should I clean it?   Can I throw it into the washing machine on gentle, or is it a hand wash only item?





I had the same problem with my screen the first time I put it up. I added some heavier duty precautions to stop that from happening and it's bee great all season long. I'll put up some pictures and descriptions when I get home to show you what I mean...

...and Once or twice a season, I spray my screen with a bleach and water mixture. 3 parts water to one part bleach, let the sun hit it for a bit and then lightly hose it down and let it dry,,,seems to work pretty well.
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1502tuley
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« Reply #8 on: September 07, 2011, 11:56:06 am »

Well the weekend was a mix of greatness and disappointment.   We had two movie nights for two different parties.   The first night was fantastic.   The PJ was bight and clear and the trapeze was fantastic.   I did have some issues with the image on the PJ shaking every now and then, but I think that was due to a faulty s-video cable (or at least that is what everyone is telling me). 

The disappointment came the next morning.   I left the screen up over night.   Well a front came through after we went to bed and proceeded to blow it down (along with everything else in my yard).    It snapped one of the frame's pipes in half at a joint (an 3/4" iron pipe no less).  It snapped the threaded part right off the end of the pipe.    The wind was so strong it pulled the anchors to the guide wires  up I had screwed into the ground.   I had been using the cork screw things that you screw into the ground and attach a dog chain to.  Those things were 1.5' into the ground and got ripped up like they were nothing.   It blew all of our pool chairs over and blew our table’s umbrella out of its base and across the yard.   It was a freak thing.

Luckily I had built two different screens and frames, I had to use my smaller BOC screen (10’ X 5.5’) for the second party.  I had to put that screen in the middle of the yard instead of at the edge of the pool due to my PJ’s throw ratio (shooting over the pool generated an image too large for the smaller screen) so that was kind of a bummer since it was a dive in movie theme.    It still went well though, it just wasn’t as nice as the first night on the larger screen. 

All things considered I was very  happy.  The first showing was great, the second on the smaller screen was not quite as good by comparison, but still tons of fun.    I was able to repair the larger screen on Monday, so we are back in business for next weekend.   

Related Question:   When the Trapeze screen blew down it got really dirty.    How should I clean it?   Can I throw it into the washing machine on gentle, or is it a hand wash only item?





I had the same problem with my screen the first time I put it up. I added some heavier duty precautions to stop that from happening and it's bee great all season long. I'll put up some pictures and descriptions when I get home to show you what I mean...

...and Once or twice a season, I spray my screen with a bleach and water mixture. 3 parts water to one part bleach, let the sun hit it for a bit and then lightly hose it down and let it dry,,,seems to work pretty well.

Thanks Krazy.   
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Jeeperz23
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« Reply #9 on: September 08, 2011, 01:37:19 pm »

Tuley.
Even a not so great BYT night is far better than NO BYT night...but it sounds like you pulled through it just fine... I always take my setup down, I have 2 different setups,the inflatable and one I made with pvc rails and white cloth, both come in for the night..  I was wondering about  rear projecting, doesnt the image show backwards ??
Love the idea of a "Dive in Movie"..

Jeeperz
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Corzak
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« Reply #10 on: September 08, 2011, 02:02:41 pm »

I was wondering about  rear projecting, doesnt the image show backwards ??

Jeeperz

Most projectors have a setting that "mirrors" the image so that it shows correctly! Wink
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Jeeperz23
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« Reply #11 on: September 08, 2011, 02:41:48 pm »

Cool, I need to check mine, would love to not have the setup in front, at least once a showing, one of the kids trips on a wire, usually we just lose a speaker for a second, but last weekend someone pulled out the power cord... everything went dark.. took about 3 minutes to get everything back on and find the correct spot in the movie.. It just became a bathroom/snack break. Somebody yelled "Intermission time" ...

Thanks,
Jeeperz
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1502tuley
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« Reply #12 on: September 09, 2011, 09:26:33 am »

Cool, I need to check mine, would love to not have the setup in front, at least once a showing, one of the kids trips on a wire, usually we just lose a speaker for a second, but last weekend someone pulled out the power cord... everything went dark.. took about 3 minutes to get everything back on and find the correct spot in the movie.. It just became a bathroom/snack break. Somebody yelled "Intermission time" ...

Thanks,
Jeeperz
Yep, I will likely not be leaving my screen up again over night.

As for the rear projection, it was great having all of the wires and stuff behind the screen and out of the way.   It was also nice not to have to worry about people passing in front of the PJ and blocking the image.   I feal much safer also not having to worry about someone tripping over a power wire and pulling the PJ off of the AV cart.
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rich92069
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« Reply #13 on: September 09, 2011, 01:19:03 pm »

you can purchase rear projecting screen material in access of 1+ gain. I know mine is 1.3 gain that I use. Da-Lite has some material over the counter and accessible to you guys with these specs or better.
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rich92069
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« Reply #14 on: September 09, 2011, 01:31:12 pm »

Even a not so great BYT night is far better than NO BYT night...
I cant agree more!!!!!!!
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