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-   -   Best DIY material for LT150? (http://www.avsforum.com/forum/23-screens/19844-best-diy-material-lt150.html)

Gary McCoy 07-26-2001 02:49 PM

Doubtfull. Higher gains are the result of "retro reflection" which essentially reflects the light back along the same path it came. If you read the archives, you will discover that some here have experimented with glass beads and silver paint and other retro-reflective materials. We have not yet produced a successfull high gain screen without horrible hotspotting, high gain apparently requires some precision manufacturing processes.

What probably comes closest is a brilliant white paint (such as Behr Ultra-White tinting base) with no added pigments and in an eggshell finish. Some have estimated gains between 1.1 and 1.3 for such paint, due probably to the very slight sheen of the egshell surface.

Such a screen would be best in a totally dark room with complete ambient light control - the darkest black will be no darker than the appearance of the white screen surface illuminated by ambient light, and may wash out further if your room has light-colored walls and furnishings, due to light from the screen reflecting first off the furnishings, then back onto the screen.

For brighter projectors you can go with a neutral grey screen paint, trading off brightness for darker blacks due to better absorption of ambient and twice-reflected light. Such a paint results from adding pure lampblack pigment to the white paint above. This is a good tradeoff for a DLP projector like the LT150 if you have ambient light or light-colored furnishings in the room. The gain would be 0.8-1.0 depending of course on how dark the gray was.

Have you considered a simple pull-down or manual screen? These are available new from about $140 and up depending upon fabric and size, not that much more than DIY. Sometimes you can find used screens for even less, the usual trick is finding a high gain fabric, most manual screens are a matte white.

Gary

ckolchak 07-26-2001 08:47 PM

just purchased some blackout fabric tonight. it looks like it may be good screen material, but it doesn't have a very reflective surface. it is however, quite smooth. in fact the one side has almost no texture at all. i got 3 yards which came out to 54" x 108" for a cost of about $19 w/ tax.
i also picked up some 1" x 2"s which were under $2 each.
i was planning on making a frame, but think i will just staple the cloth to the top and bottom and then cut another 1x2 to stretch it taught once its the two ends are screwed on the wall.
it may not end up being a great screen to mate with the 150, but it should be better than a sheet and it's not really that much of a premium if i eventually do go with the high power.
only thing is getting the creases and wrinkles out of it anybody have any suggestions?

chris larralde 07-26-2001 10:34 PM

Sounds like the Da-lite h-Power 2.8 gain screen is the best match for this projector. I've read through Brett's lengthy (very informative) thread on screen materials, but most seem geared torward a 1.0 gain.

Since I can't afford a screen yet, are there any materials like the blackout cloth that can approach a 2.8 gain?

regards,
chris

BIGRICH 07-27-2001 12:55 AM

Here is the definitive response:


BUY A SCREEN!

You are not going to be happy until it is right, so you might as well buy the screen now!

chris larralde 07-27-2001 11:15 AM

BIGRICH,

Well, I wish it was that easy. I happened to get my LT150 for free (part of a trade). So as I wait for the funds to purchase a proper screen, I'll have to settle for DIY or nothing!

After further reading it sounds like a lightweight frame with blackout fabric is the easiest and most portable solution. I'd like to experiment with paint and have read numerous recommendations for SW luminous white, Behr ultra-pure white, ralph lauren etc. Has anyone come to a conclusion on the highest gain white paint? It looks like the Behr has been measured at 1.4 gain. Anyone come up with something brighter?

regards,
chris

ckolchak 07-27-2001 06:54 PM

i would think the problem with using the equivilent of a hi-gain white paint would be the inability to produce a uniform coat, no matter how much time and prep work you put into it. if the coat isn't uniform, you would get hot spots, wouldn't you? i don't think you would run into the same problem with a matte paint or just the blackout fabric.

Gary McCoy 07-29-2001 03:23 PM

ckolchak, we have had excellant results using a painters pad and 2-3 coats of paint on a stretched blackout cloth screen. Since I wanted a screen wider than the 54" cloth, I started with a cotton bedsheet and applied 3 coats white paint over latex primer. No hotspots, no hassle. Take your time and use care and I would expect a good result.

As I said before, where hand application does not suffice is when attempting higher gain screens with glass beads and metallic pigments - nor does simple spray apparatus help. I would venture to guess that screen manufacturers may use proprietary manufacturing processes designed to evenly apply retro-reflective materials, using special equipment, perhaps even paint robots a la Detroit automobile finishes. If you need such a surface, buy it, unless you have the time and money and inclination to experiment. Some day someone may well come up with a satisfactory DIY high gain surface. As for me, I achieved "good enough" first attempt, so now I keep an eye on this forum for new developments, in between watching DVD movies.

Gary

Grant Smyth 07-31-2001 08:03 PM

The "blackout" material works well with the LT150 - I know since I have tried it. The Hipower is the best I have seen with the LT150, but the brighter of the blackout materials is very good - you will be pleased, especially considering its price! You can order it rolled, so no creases! That's what I would do if I were going to use it for a permanent screen and then tack it flat to a wall.

A proscan DVD player + LT150 + blackout material = a very good picture (mask the screen with black material to expunge DLP halo and increase preceived blacks and contrast).

A HTPC + LT150 + Da-lite Hipower is extremely good - aim for this!

Cheers,

Grant

ckolchak 07-31-2001 09:35 PM

i just cut some cross braces 1 1/2" longer than the actual measured loose screen height and screwed them in-two at the ends and one in the middle, and the blackout material stretched tight to fit them in. most of my wrinkles are gone and boy...this stuff does stetch!. i have to now staple the sides of the canvas to the outer cross braces and that should remove all the wrinkles. this material was seriously creased when i bought it, but the stetching has removed just about all traces. i'll probably use two more cross pieces just to give it some more support and then hang it on the wall like a picture.
all together i've spent about $30-40 and it took about an hour to put together. if nothing else this will help me audition & orientate the projector for when i do step up to the hi-power screen a few months from now.

chris larralde 07-31-2001 11:00 PM

Sounds like the blackout material is the safest, cheapest, and easiest way to start out. Perhaps the painful wait for a Hi Power Dalite won't be as bad as I thought.

regards,
chris

ckolchak 08-03-2001 12:55 AM

i'd be very interested to hear how you make out if you intend to use any kind of paint.
my pj came today and after about 6 hours with it, i'm going to be looking into getting samples of the hi-power. the blackout material just has no snap and i'm having a very hard time calibrating the colors.
after getting over the wow factor due to the sheer size, i'm now in "yeah, but i need to tighten this up... whatever it takes" mode.
most of the quibbles i have are no doubt due to the poor source (interlaced s-video) and the screen. it's not unwatchable, but i can definately envision another surface giving the picture so much more kick.


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