DIY Video Projector Part II - Page 4 - diyAudio
Go Back   Home > Forums > General Interest > Everything Else > The Moving Image > DIY Projectors

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 28th June 2002, 03:14 AM   #31
diyAudio Member
 
Join Date: Jun 2002
Location: Gulf Coast, Punk
Send a message via AIM to noodles Send a message via Yahoo to noodles
I was kinda interested in seeing how cowan's forum was coming along. It had more appropriate categories for this kinda thing.

When I put my Spectra C on my OHP, do I need to take the stage glass off the OHP first? Mine has two layers of fresnel, the glass, then the Spectra on it. My LCD itself is quite a bit smaller than the stage and there's lots of space left. But the rest of the LCD panel covers it up. Should I worry about this?

Oh yeah, I just remembered. What aspect ratio should I be using with the Spectra C? My screen is 4'x7' Visqueen plastic. It's barely thicker than a shower curtain. Do I have to cut it to 4:3? Will it leave out light, or does it project black at the top and bottom of widescreen?
  Reply With Quote
Old 28th June 2002, 03:46 AM   #32
cowanrg is offline cowanrg  United States
diyAudio Member
 
cowanrg's Avatar
 
Join Date: Apr 2002
Location: Lafayette, CO
Send a message via AIM to cowanrg
yeah, i really wish people would have been more interested in my forum... i just didnt have the time for it to work (as of now....). im just one person :-)

i didnt touch anything on my OHP to do what i did. i only removed the LCD panel and housing from the spectra c. mine just has mirror, fresnel, glass. but i have a 1" thick fresnel, that is kinda encased (not really, but both sides are smoothed, its kinda like enclosed.)

as far as the size of the spectra, that's what makes it ideal. with normal OHP's you get a hot spot in the middle, and the edges have little light. the spectra is situated in the middle of the stage, and therefore where the majority of light is.

this allows it to have the most light possible. i tried this with larger lcd's and the image was MUCH dimmer. plus, if you totally mask the rest of the stage (recommended), you get VERY little (none if you are good) bleed through from the excess light. mine projects ONLY the panel, and there is NO light coming from the projector, except for the fan vents.

so, i suggest mounting panel fairly flush (mine has rubber pads to create a ~1/4" gap that allows for airflow underneath panel.) i noticed that the extra light that bled out brightened room, and in a sense, created an ambient light equal to a small lamp being on. making the image a tad more washed out.

now, the screen. since we use really shi**y LCD panels (150:1 contrast ratio is BAD in the relative sense) blacks aren't quite black. on a spectra, we get a kinda dark grey. there are a few ways around this.

if you only watch widescreen or letterbox (or fullscreen, read further), mount your screen so it's at a level where you can lower it JUST enough for the picture to be shown on the screen. however, the light from the "black" bars will just go onto the wall or whatever, and wont look to swift (yeah, i said swift :-)

so, i do the ghetto version. goto an art store, and get some picture frame matting. if they are nice (or if you are a smooth talker) you can get them to cut some for you. or give you some for free.

take the strips, and cut them the width of the LCD panel. now, you have inserts that you can set inside the LCD frame (on the spectra, there is a black "ridge" piece of metal that kinda makes a frame for the lcd. you can set these strips of matting inside this, and bam! you have a letterbox. get them for various aspect ratios. just play a movie and measure the dead space on top and bottom.

it looks AWESOME if you do it right. you get a widescreen image projected, with SHARP corners. it looks like its that res native. it really looks great.

for the longest time, i just used 2 pieces of thick letterhead paper, and just kinda propped them on top of the panel, so that they cut out the black strips.

but with any panel of this low contrast, you will have nice and ugly grey bars projected. its even worse if you have a high gain screen, like a glass bead impregnated screen like i do.

plus, another tip for DIY screeners, put a nice black edge on the sides of your screens... this will look a lot better than trying to fit the image perfectly inside the screen. this will give you a better margin, and if its a nice black, you wont even be able to tell the projected image is overlapping.

well, thats my 2 cents. hope it helps some people. da**, long post, guess i had to make up for my lack of posting lately. hehe.

Quote:
Originally posted by noodles
I was kinda interested in seeing how cowan's forum was coming along. It had more appropriate categories for this kinda thing.

When I put my Spectra C on my OHP, do I need to take the stage glass off the OHP first? Mine has two layers of fresnel, the glass, then the Spectra on it. My LCD itself is quite a bit smaller than the stage and there's lots of space left. But the rest of the LCD panel covers it up. Should I worry about this?

Oh yeah, I just remembered. What aspect ratio should I be using with the Spectra C? My screen is 4'x7' Visqueen plastic. It's barely thicker than a shower curtain. Do I have to cut it to 4:3? Will it leave out light, or does it project black at the top and bottom of widescreen?
  Reply With Quote
Old 28th June 2002, 03:58 AM   #33
Undream is offline Undream  United States
diyAudio Member
 
Join Date: Apr 2002
Location: Adrian, MI
Send a message via ICQ to Undream
cowang, darn you. hehe. I already had this idea, and had yet to post it. I'm going to be taking sheets of really cheap sheetmetal, and cutting them to look like this:

Click the image to open in full size.

I'll make one for 16:9, and 2.35:1, and just slide the sucker right into the side of the projector (I'm making one side of it on hinges that can easily be swung open) whenever I watch a widescreen movie.
  Reply With Quote
Old 28th June 2002, 05:11 AM   #34
diyAudio Member
 
Join Date: Jun 2002
rats, both cowan and undream beat me to my revolutionary solution. we just find whatever scrap paper or trash we might find on the floor (junk mail works good) and line that up to block the light.

seriously, thanks for the tip cowan. i think ill find some matting soon.

btw, im gonna buy a little digital thermometer from radio shack for $20 to monitor heat. what do you think about putting a PVC 90 corner over the vents to cut down the light some? think it will block the flow enough to overheat the innards?
__________________
Operation: BIG SCREEN!
results, info, and pictures...
  Reply With Quote
Old 28th June 2002, 05:17 AM   #35
diyAudio Member
 
Join Date: Jun 2002
Location: Blacksburg, VA
Default Screen's done.

Hey guys. I finished my screen a few minutes ago. If it looks crooked on the right, it's because the base was further way from the wll on the right than on the left. When put flat against the wall, it's perfectly square. For a reference point, the TV on the left is 35" diagonal.

Click the image to open in full size.
  Reply With Quote
Old 28th June 2002, 05:36 AM   #36
Undream is offline Undream  United States
diyAudio Member
 
Join Date: Apr 2002
Location: Adrian, MI
Send a message via ICQ to Undream
awesome is that plastex? nice to see someone following in my footsteps.

its fun as hell to build, huh goes together so darn quick. so much easier than the crappy projector itself. You think to yourself.. Hey, I *am* capable of doing something after all!!!

hehe. then you go back to your projector
  Reply With Quote
Old 28th June 2002, 05:37 AM   #37
cowanrg is offline cowanrg  United States
diyAudio Member
 
cowanrg's Avatar
 
Join Date: Apr 2002
Location: Lafayette, CO
Send a message via AIM to cowanrg
the matting works well, becuase its easy to get, and it blocks light. plus, if cut right, they fit RIGHT in the corners of the panel, and takes about 1.2 seconds to box out your panel.

as far as the temp guage goes, dont even bother. here is a rule of thumb for panels, if you can put your whole hand over it when its on, and it isnt uncomfortable, its fine. if its kinda hot (meaning it almost hurts), its too hot. they can stand up to quite a bit. you would really be surprised how hot their tolerences really are. and believe it or not, our skin is one of the most accurate thermometers. save the $20, and just use a hand test. if YOU can handle it, so can your panel. we have low tolerences for heat.

of, if you wanna spend $20, let me know, ill give you my paypal account :-)

sorry about beating everyone to the tip. hehe, i still lurk around here every so often.

Quote:
Originally posted by SuperZoboo
rats, both cowan and undream beat me to my revolutionary solution. we just find whatever scrap paper or trash we might find on the floor (junk mail works good) and line that up to block the light.

seriously, thanks for the tip cowan. i think ill find some matting soon.

btw, im gonna buy a little digital thermometer from radio shack for $20 to monitor heat. what do you think about putting a PVC 90 corner over the vents to cut down the light some? think it will block the flow enough to overheat the innards?
  Reply With Quote
Old 28th June 2002, 05:38 AM   #38
fender4 is offline fender4  United States
diyAudio Member
 
Join Date: Dec 2001
Location: USA
Hey Undream...I'm disappointed! Why stop at hinges? I want to see some automation! How about an auto-aspect ratio selector controller from an HTPC? Sorry, couldn't resist.

Good ideas, everyone.

SuperZ,
My math is terrible, but I came up with:
90" diagonal, 4:3
72" width X 54" height

My blackout material is also 56", so I left an inch on each end to play with. To construct these dimensions with the 4'x8' foam board will require some cutting and gluing. There will be 24" of length left after I cut the board down (because of the 4:3), so I will use the excess material to fill in the missing height (48" extended to 54". I will try to be precise with the cutting and gluing, but since material will cover it, absolute precision is not critical. I will probably add a black felt border. It seems like the practical thing to do.

I hope to make some progress this weekend on the screen and the projector housing. I am still looking for a Marklar-esque reflector for a MH setup, so in the meantime, my DYS halogen-powered projector will double as slow-roaster. Should work out great for the 4th of July!

-f4
  Reply With Quote
Old 28th June 2002, 05:42 AM   #39
cowanrg is offline cowanrg  United States
diyAudio Member
 
cowanrg's Avatar
 
Join Date: Apr 2002
Location: Lafayette, CO
Send a message via AIM to cowanrg
i actually had plans for a motorized setup for my aspect ratios, but to tell you the truth, it would be hell! you would have to get a stepper motor, motor controller, and basically have set aspect ratio sizes programmed, etc, etc, etc, etc..

so, i thought to myself... why!? im usually one to overdo things, and typically, if its a hassle, i go for it, regardless of benefit :-) but this was one of those things that for the simplicity of dropping 2 cardboard pieces down on the panel, as opposed to building a contraption (which wouldnt work as well, because it would have to set OVER the panel, couldnt set right on top, because of space issues, you wouldnt even have crisp clean lines....

been there, thought about it, didnt done that.
  Reply With Quote
Old 28th June 2002, 08:34 AM   #40
diyAudio Member
 
Join Date: Jun 2002
Location: Gulf Coast, Punk
Send a message via AIM to noodles Send a message via Yahoo to noodles
We're already ghetto-ing the projector, why not case mod it? A thermometer would be kewl if it was backlit. Window kits would be kinda stupid though for these cases.

Well you could line your (let's call them) "aspect boards" together, kinda like a book. And put a hinge on the top/bottom. Then you can just flip the one you want over and WHAM!!! You got yourself some keen innovations. The only thing you have to worry about is the order you put them in. Don't put the one with the big hole in the front, because it will block the ones with the littler holes. Get what I'm saying? Maybe I should draw a pic for it.

minutes later:
Click the image to open in full size.

Yeah, I'm no artist when it comes to MSpaint. But it basically shows the order of the boards. Putting them in this order will prevent them from covering each other up. Pretty average concept. This is the kinda stuff that comes out of my brain when I don't go to sleep.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 09:31 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2