CurtPalme.com Home Theater Forum

[rdmiller]

my apologies if this has been answered before, I just cannot get my mind around this. I am looking though the projector rankings, and I see resolution, supported HD (720 vs 1080 i/p) and bandwidth. As I understand it, I can get a 1080i image with 36 khz, 47 khz will bring me 720p, and perhaps 72 khz would support 1080p.

I read max resolution listed, seems to average about 1280x1024. this seems a bit short of the 1920x1080 that represents HD. (btw, my skin crawls with the marketing of "true hd", but that is for another day). If I was to feed a 1080i image into one of the projectors rated for 1080i but a screen resolution that has a lower maximum would I lose data/ image compared to a projector that is rated beyond the 1980x1080?

oh yeah, while I have your eyes. contrast ratios. seems that the digital units are claiming 100,000:1 CR's. if the g90 only goes to a 30,000:1 CR then what is actually happening here?

thank you.

Richard Miller

[akajester]

I can't comment on the first part, but contrast ratio has changed in the past few years. It's now called "dynamic contrast ratio" or a nice marketing shift to trick consumers into thinking their new panels can do black.

You can check out more here;
http://en.wikipedia.org/wiki/Contrast_ratio

dale

[beun]

On the resolution issue, yes you will lose. The projector will scale the picture to make it fit into its native resolution. A 1280x1024 projector by the way sounds like a business projector to me, it's a 5:4 aspect ratio commonly used in computers so feeding that one a 1080i/p picture will result in big black bars on top and bottom.

[JOneil]

[beun]

Correct, but a CRT based projector will probably specify vertical lines and scan rate and bandwidth which is another way of specifying horizontal resolution.

The original post was not clear if it was about CRT's or digital displays, but the numbers mentioned lead me to think digital.

[ecrabb]

Guys, if you go back and read Richard's post again, I think the resolution question was specifically regarding the "Max Resolution" column on Curt's Projector Ranking "best/worst" list... In that case Richard, that column is essentially meaningless - at least in any technical context. You can pretty much ignore it.

No CRT projector will display a 1080i or 1080p picture "perfectly". With CRT's, we talk in terms of sharpness, or more technically "resolving power", which is how close to reproducing the source the projector can get. A high-end 9" machine can get very close (though it's not as sharp as a digital - which some of us actually prefer), an 8" machine is less sharp, and most lower-end 7" machines resolve well under half of a 1920x1080i signal. In less technical terms, 9" machines can do 1080p pretty well, 8" machines 720p or 1080i very well, and 7" machines a softer 1080i or 720p.

Read this:
http://www.curtpalme.com/CRTPrimer_14.shtm

On the contrast ratio question, basically the numbers really aren't comparable. It's a deep subject, but suffice it to say the two numbers weren't measured the same way. A G90 can be set up to display a nearly infinite on/off contrast ratio (though you wouldn't want to set it up that way. Digitals are now turning in some excellent on/off contrast numbers, not necessarily because they can produce a great black (many won't), but more because they're so damn bright.

There are plenty of articles to read if you want to read up on ANSI contrast versus dynamic (on/off) contrast. Google or search for a few discussions here or over at AVS Forum. Everything you ever wanted to know about sharpness, resolution, contrast, etc. can be found here, at AVS, or on the web.

SC