CurtPalme.com Home Theater Forum

fefrank · Joined: 10 Jun 2012 Posts: 83

This is not clear to me. I keep reading and hearing that A machine let's say a BG1208s has HD8's but HD8's are not capable of resolving 1080P? but Hd-145 lenses are? What is the difference? I thought that the projector tubes were the ones who resolve resolutions. So how would a 8500 Marquee with HD-145 lenses resolve full HD but not with HD-8's? This is a topic that was discussed in one og the threads I found around. Can someone explain this to me?

virusc · Joined: 11 Apr 2007 Posts: 358 Location: Massachusetts

the problem is HD-8's are not that good of a lense especially at the edges. HD-145s when used in the sweet spot screen size range (can't remember exactly right now) are in fact much sharper and have better contrast due to the lense containing more glass elements or just being better engineered. However, their can be issues if you run you raster very large or the lenses are close to the crt faceplate or both. This is why HD-8's were used more often.

ecrabb · Posted: Wed Oct 31, 2012 2:55 pm Post subject:

Think of it like this: The CRT's are the retina; the lens is the cornea. If the cornea sucks, it doesn't matter how great the retina is.

The fact is that most HD-8 lenses were engineered and manufactured for CRT projectors when signals like 480p and 600p were the dominant resolutions.

There are also apparently variants of the HD-8. The HD-8's that were on Sony 12xx sucked ass. The tubes in 12xx's were MUCH higher resolution than the lenses, easily resolving 1080i scan lines on the phosphor, while the lenses resolved something less than half that (scan lines were invisible).

Apparently, the HD-8's on 8500's were much better than what shipped on the Sonys. I always wanted to try a set of 144/145's, but Joust's mods cost as much as my projectors. I moved on to LC before the itch ever got strong enough.

SC

ElTopo · Joined: 07 Nov 2006 Posts: 1640

If you use P16 high rez tubes (8 inch) with HD-145 you get a very good picture on your screen.

ElTopo

digitalayon · Joined: 02 Mar 2009 Posts: 921

Felix, I am not sure if lens really matters in terms of 1080p. A HDFury will make so so you can set it at a lower resolution if you need but will not lose anything in terms of detail. The lens swap will assist with corner focus and color filtering.

fefrank · Joined: 10 Jun 2012 Posts: 83

When I fired up the 1208s I thought that 1080p looked great even with the Standard HD8's. I do have to say that 720p looked sharper. I saw the screenshots of joust's projector with hd-145 lenses. Was that a marquee 8500 he was using? if that was an 8500 that was a very sharp picture for being 180DVB22 tubes, unless he was using other tubes in the projector or it was an LC. does anyone know? I am just like the kids who want to peek into their christmas presents before christmas day comes around.

All I know is that corner focus on hd8's is extremely horrible. I can't get it to focus a 16:9 Screen on the edges or corners. It's kind of sad. the middle does great though. I like the way ecrabb explained that by the way. It makes more sense to me now.

I am planning on using my HTPC for this instead of a bluray player with a moome or an hdfury. VGA to RGBHV. It's that a downside? Would I get better PQ with this setting:

Bluray Player>--HDMI>---Moome Box (HDFury)>---VGA to RGBHV Cable>--- Projector

I am currently using:

HTPC>----VGA to RGBHV cable>---- Projector

What are your thoughts on that doing 1080p which one will give me a cleaner picture?

ecrabb · Posted: Wed Oct 31, 2012 6:56 pm Post subject:

You'll get varying opinions on this, but I always much preferred 1080i to 720p. It makes no sense to me to throw away a bunch of picture detail digitally so that the projector will resolve it better. Great! You now have a perfectly resolved (inferior) picture! But, like I said, everybody has a different opinion on this. I also like it better because I didn't use an HTPC, so I was running 1080i/60, which gives you smoother 24p playback than does 720p 60.

If you're going to use an HTPC, then it solves the frame rate issue. First of all, you can run 71.928Hz or 47.952 if you like and not worry about interlacing.

For a computer desktop display, you do care about fully resolving, because if you don't, it can make the desktop icons, text, menus, etc. hard to read. In that case, you probably do want to do something like 720p.

What you might want to do is play with something like the Nokia monitor test app at some different resolutions. Turn off R and B and don't even worry about convergence... Just try some different resolutions between 1080p and 720p and see what's the best tradeoff between sharpness and resolution. Perhaps 1440x810, or 1600x900 might be the ticket.

Regarding corner focus... How close are you running the corners to the edge of the tube face. The closer those corners are, more trouble you'll have focusing them. A lot of guys here chase maximizing their rasters so hard, they completely screw up any semblance of corner focus ability. Of course, you can rationalize that because A) you're not usually looking at a desktop, and B) you're not usually looking at the corners.

As for STB vs. HTPC picture quality, they should be very similar, with the caveat that you get much more flexibility with the HTPC on signal resolution, refresh rate, etc., but also more hassle, too.

SC

digitalayon · Joined: 02 Mar 2009 Posts: 921

Hey Felix....I think Crabbs LCOS has our stuff in it.

fefrank · Joined: 10 Jun 2012 Posts: 83

It definetly has. I just made some parts for JVC not too long ago. They were interesting and Really expensive!!! by the way.

ecrabb · Posted: Thu Nov 01, 2012 4:13 pm Post subject:

fefrank · Joined: 10 Jun 2012 Posts: 83

We work for a company that makes polarizers for most digital projector companies in the market. Mostly for LCOS and LCD's. I probably made the one inside your projector! Wink

, depending on when you bought it, since it is a JVC RS45, each Lcos panel has a polarizer to help with contrast and color. so you would have 3 polarizers in there, one per panel (Green, Blue, and Red).

ecrabb · Posted: Thu Nov 01, 2012 6:50 pm Post subject:

Very cool! I've never seen the JVC's torn down... Are the polarizers glass in these machines?

SC

digitalayon · Joined: 02 Mar 2009 Posts: 921

Sort of in the glass moreless.....there are several steps and process's in making what we call the "wafer". All done in clean rooms and very very expensive to make!! Felix is our post fab guy. I just handle the IT end.

fefrank · Joined: 10 Jun 2012 Posts: 83

digitalayon · Joined: 02 Mar 2009 Posts: 921

ecrabb · Posted: Fri Nov 02, 2012 8:51 pm Post subject:

Thanks, guys! Cool stuff.

I'd love to see a JVC torn apart and understand the hardware like I do CRT. I know they're just "consumer quality" and nothing like a Barco or DPI inside (which is why they aren't $20,000+), but I'd love to see how they compare in build quality to your average run-of-the-mill ~$1000-1500 Epson or Panny. They sure seem to be much more solidly built going by weight and overall feel.

SC

fefrank · Joined: 10 Jun 2012 Posts: 83

fefrank · Joined: 10 Jun 2012 Posts: 83

digitalayon · Joined: 02 Mar 2009 Posts: 921

Yeah they are xray division.