CurtPalme.com Home Theater Forum

[noos@xp37+]

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Hello,

I want to go for the curved screen solution in the future. Probably I can use some of my old equipment, probably not. I even would start over again and buy new toys, but I do not want to go the trail and error way again. So I would like to ask all the people here that have gathered experiences with curved screens and CRT projectors to share their knowledge. So, please let us unkowing know what lenses to use and which geometry of certain CRTs allows best curve angles.

I have heard about the G70VR and the ultra rare HD-134 to focus good on curves. And I heard of some BR 909 lenses that should be good for curves. Right, wrong? What about the HACC, HD6/8, HD144/155, HD117/114, HD 215 and so on?

On this thread in the middle you can download the great torus/curved calculator - see for yourself what it does for you...

http://archive2.avsforum.com/avs-vb/showthread.php?p=5627244&&#post5627244


So, feel free to join the discussion


Greeting from Germany


noos

[Chuchuf]

As posred on AVS:
On 9" CRT's the Sony G90 HD10F (not the 1292 HD10F's) do a pretty good job overall on a mildly curved screen.
Then of course there is the HRQ900 lens's that were designed for a curved screen. Also the Manaquin lens's are curve screen as well.

Terry

[Tom.W]

How do tell if the Delta HD10f is from a G90 or a 1292 ?

[zGman]

The 1292 hd10f 's that I have seen all have a felt gripping surface applied around the barrels,
also. on later model lenses, there's a small print serial #, which I have observed the first
four numerals have always corresponded pretty closely to the PJ's build year. This has
been true for the hfq900's, gt17's. and several sets of 10f's that I have had thru here in the
last couple years.

I think there is a hRq900 that was made for curved screen. for the OP, these are all
9" lenses. I am using a curved screen (in the H direction only) for a gaming system,
with an old 1208 and HD8 lenses, and it's working out alright, there's a lot of curve,
so the corners aren't so sharp - but its just a driving game, so that doesn't matter...

For a curved or torus screen to work well, you will need a higher gain (retro-reflective)
material. If you use a material that has good angular dispersion, the contrast will go to
heck. Although, oddly, the wilsonart material I am using for mine is working pretty well
for the gaming - but haven't 't watched a movie on it - yet....!

G

[Tom.W]

Both made by Delta ? Seems like the lens design should still be the same ?

[zGman]

Hi Tom,

I guess I am not the only insomniac around here! (and a very merry christmas to you as well!)

Anyhow - the G90 hd10f are much more similar to the hfq900's (hd10E) in extensive testing
here and at Terry's. They have a lot more 'depth of field' - if that is the right photographic term.

The 1292 lenses are good - don't get me wrong - but the later model design is more advanced in
AR coatings and the ability to have great uniformity of focus across the screen, and an amazing
ability (equivilent to the hfq900) to get good edge and corner focus on Terry's 'torus' 10' wide screen,
plus a greater range of screen widths before running out of focus...Good luck finding a set though..!

One thing I learned this year - somewhat unrelated - is that the HD120 lenses as supplied on the Cine9
(runco DTV-1200 and also the DTV-1101) are actually very impressive. We did a heads up
comparison here with the DTV-1200, and the HD120's seemed to have slightly better intra-scene
contrast than the hfq900, and could still obtain good corner focus. But they are limited in 'depth-of-field' and
workable screen sizes compared to the hd10f(g90) and hd10e(hfq900). I will be fine using them
on a 96"x54" screen though, that seems to be the ideal position.

Regards,
Galen

[noos@xp37+]

For a curved or torus screen to work well, you will need a higher gain (retro-reflective)
material. If you use a material that has good angular dispersion, the contrast will go to
heck. Although, oddly, the wilsonart material I am using for mine is working pretty well
for the gaming - but haven't 't watched a movie on it - yet....!


Hello zGman,

and thanks for the data on the HD-8 in your driving simulator. How much is much curve in your setup? Could you tell me how many inchs or cm the left and the right corner are delayed to the front. And how wide is your screen. This will give me an idea how many percent of delay the Hd-8 could handle. Do you have a chance to test the HD 144 or the HD145 lenses in your configuration? I am happy to hear about the HD-8 because I have a good unused 1272 with them (HD-8m) here around. Was thinking to get 145s for it, but this depends on their curved abilities.

Thanks to all the others providing hard data


Best wishes


noos

[CRT_Ben]

Good info here, I just wanted to clarify something. Galen says you need a retro-reflective screen, I believe this is incorrect. I don't think that curving a retro-reflective screen (such as the Dalite Hi-Power that I have) will have the desired effect. As far as I know, only angular reflective screens can be used for curved and torus screens, there was a discussion about it here:

http://www.curtpalme.com/forum/viewtopic.php?p=83058#83058

Interesting about the HD-120's though!! How much of an improvement do you think these are over regular HD-10's?

[Tom.W]

Making a great lens is an art in itself !

[zGman]

Hi Ben,

Thanks for the clarification on the screen type - my limited understanding was simply
that a limited angular dispersion is important so the the rest of the image isn't
washed out.

As far as the HD120's - the one's I have tested came on 2001/2002 Barco/Runco
models. The Barco Cine9 brochure lists the lens as HD120, but the Runco version
has no label. Within their range, the focus is equivalent to the G90 hd10F, but
you have to work harder for it, and they won't work well for a curved screen.
Gets back to the depth of field idea, and/or range of outer region focus control.

For noos, I will take some measurements and post a couple pics maybe over
the weekend - too much going on for the next couple days.

I can tell you I am almost 8' wide, the depth of the curve is about 10",
the radius of curvature is about 9' or more, and the PJ is table mounted
with quite a lot of angle, so the the lens optical axis is centered on and
perpendicular to the screen, which is very close to the floor. This would
be considered "0" projection angle, which is important, because the offset
projection angle typical in an HT will "use up" all the depth of field of the lens.
At least that's how I understand it.

We tested this somewhat inadverdantly by doing the initial test setup
with the screen frame leaning agianst the wall. corner focus was poor,
but when we got the screen stand roughed in at the corect angle,
focus improved considerably. (and yes we know about schliemphlug...!)

You can test for focus range in your set-up using a nice sharp grid
pattern, a friend, and a square of white cardboard.

Tom - I totally agree, lens building is still an art, and my experience is
that 3M/Delta has gotten better and better over the years. I have a set
of 2002 HD8's here that are very much nicer than the 1996 models...

Regards,
G

[Tom.W]

I think it is safe to say the lenses are getting better

[noos@xp37+]

Helllo,

and thanks for all the data you provided. It really helps a lot to consider the path for the future setup.

Thanks

noos

Any other experiances are still welcome...

[noos@xp37+]

[gjaky]

I have two (not three) pieces of unfiltered HD6-Ds (and one HD6-C not ML, unfiltered) if you want you can grab them for free just pay the shipping from Hungary or pick up locally

[noos@xp37+]

[gjaky]

I think the HD6-D were in electrohome ECPs the HD6-C is from a barco (because there is a barco sign on the sticker)

[Spanky Ham]

Interesting test. How do you measure unsharp?

[noos@xp37+]

[gjaky]

In the meantime I got a set of Sony PT-65 lens for free, if you need you can get is as well (ps. one of them have broken two of the mounting "legs")

[noos@xp37+]