CurtPalme.com Home Theater Forum

SYC · Joined: 16 May 2006 Posts: 269

How much can a curved screen improve the corner focus of a CRT? Is it worth doing so?

SYC

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

It depends on what lens' you have on your PJ, some can do curved screens well, others can not.

Athanasios

stefuel · Posted: Sat Jan 31, 2009 1:22 am Post subject: Re: Curved screen for CRT?

SYC · Joined: 16 May 2006 Posts: 269

SYC · Joined: 16 May 2006 Posts: 269

ecrabb · Posted: Mon Feb 02, 2009 2:59 am Post subject:

Pretty much all modern lenses that I'm aware of are designed with a planar focus field. Not only will a curved or slightly curved screen do nothing at all to improve corner focus, degraded corner sharpness is actually one of the risks with going to a torus...

Corner focus on a curved screen all depends on how much depth-of-field a particular lens has at the focal length (throw distance) you're using. That's why Athanasios said it depends on the lens whether you'll have trouble or not. Some lenses have more than others, but all CRT projector lenses are a large aperture design to minimize light loss, and consequently all have shallow depth of field, relatively speaking.

The bottom line is that there is an awesome benefit to going to a curved screen (high gain, with better uniformity), but corner focus isn't one of them.

SC

SYC · Joined: 16 May 2006 Posts: 269

Got it.

SYC

n@t · Joined: 02 Apr 2006 Posts: 63

Hi

I had HD8 Lenses with good results. (BG808s)
With HRQ904 Lenses is perfect! (BR909)
Previously HFQ900 on the 909. It was ok!

Bernd

stefuel · Posted: Tue Feb 03, 2009 11:34 pm Post subject:

You can get perfect focus on a flat screen. So tell me how you can get better than perfect focus on a curved screen?

WanMan · Joined: 19 Mar 2006 Posts: 10270

Why is this not in the screens chatroom?

n@t · Joined: 02 Apr 2006 Posts: 63

crt projectors · Joined: 03 Oct 2007 Posts: 39

It's funny how things go full circle. The ancient beast in my avatar uses a curved screen. The gain results are awesome, the only drawback is picture is at a reduced viewing angle. The screen is still viewable at most angles, just at a reduced brightness. Your seating in the video sweet spot is near the center of the screen. Situate some audio towards the screen and the sound should bounce back at you, appearing as if coming from the screen.

This was Advents brainchild of total video and audio immersion. The Curved surface of screen acts like a huge parabolic mirror reflecting maximum light directly back at the viewer with the bonus of sound. Those engineers at Advent REALLY knew their screen technology, the screen was an integral part of the PJ That made the 1000 viable. This was needed due to low light output of PJ. I have personally experienced these results with this PJ in the last year.

Long ago I owned a Novabeam and it was fine without a curved screen aside from the edges being out of focus since picture projected flat as did not have correct screen. That one had a much brighter picture and the curved screen was less critical for overall bightness.

How much does a new curved screen costs? Who makes them now? Are they white or silver in color on surface?

CAN someone please also reply on where to get lenses to make newer PJs to do this. I guess a high perfomance PJ should have great results with this screen method-- please anyone vouch for this.

David_Web · Joined: 02 May 2007 Posts: 418 Location: Sweden

IIRC Curt has converted projectors from curved to flat that came out of planetariums and similar installations. So he'd probably know what's involved in doing it the other way.

How about bolting on LC lenses to an AC machine or vice versa. Should work to produce some sort of curved image.

n@t · Joined: 02 Apr 2006 Posts: 63

Hi,

my Screen is a Studiotek130 curved.
I can make a Screenshot.
What should I shoot?

Bernd

SYC · Joined: 16 May 2006 Posts: 269

n@t · Joined: 02 Apr 2006 Posts: 63

Hi,

sorry for Delay....
My Cam is bad Crying or Very sad

Regards