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Good used/entry-level digital?
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kal
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Joined: 06 Mar 2006
Posts: 16032
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 3:28 am    Post subject: Reply with quote


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Sorry, missed these previous comments:

cmjohnson wrote:
But it's irrelevant in my own particular situation as the room places certain limitations on how I can set up this [digital] projector. The relatively short throw and relatively wide screen demands that I'm running the RS45 with the zoom lens pushed close to its wide angle limit.

Performance of the digital projector will therefore be compromised and what you see will not be the projector performing at its best contrast ratio. It'll be brighter however. As a CRT owner, I'm sure you'd prefer contrast ratio over brightness however (I do).

Quote:
But, it's very nearly a straight-on shot from the projector to the screen. My keystone correction is 2. Just 2 points of keystone to match up the edges.


Don't use keystone at all as it destroys resolution!

I'm sounding like a broken record, but again, you need to read my "digital projectors for CRT users" hints here: http://www.curtpalme.com/forum/viewtopic.php?t=32973

I "translate" a lot of things for CRT owners looking to get into digital.

A quote:

"Don't use keystone at all as it destroys resolution! On a CRT projector the pixels are squished so you never lose any, on a digital it has to throw away pixels instead so you don't want to do any digital manipulation to the resolution at all. Instead you get the projector perfectly level with the screen and then use lens shift to shift down to keep all 1920x1080 pixels. The only exception where this may be ok is on a higher resolution 4K projector that is only used for 1080p content (since you have spare pixels you can throw away without decreasing the source resolution). I suppose they only have keystone adjustments for those really oddball installations where you absolutely must have the projector off to the side and not centered on the screen. "

If you need to use keystone you're not setting the projector up straight/level/etc. Turn off keystone completely then get the projector square.

Kal

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Jeremy112



Joined: 28 Sep 2006
Posts: 2643
Location: Fond du Lac, WI


PostLink    Posted: Fri Dec 23, 2016 3:46 am    Post subject: Reply with quote

Yes, exactly what Kal said on Keystone, DO NOT use it, it totally compresses the image, sure the newer PJs do it better than the older digitals, but it is still lightyears away from being perfected.

With a projector like the RS45, I would think it would have enough lens shift to not need keystone at all...

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cmjohnson



Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s


PostLink    Posted: Fri Dec 23, 2016 4:32 am    Post subject: Reply with quote

It has a huge range of lens shift but in order to run zero keystone and use lens shift to reshape the raster to exactly fit my screen, it would demand that the projector be placed where I can't place it.

I am using very LITTLE keystone, only 2 points worth, and that will just have to do for now.


Every installation requires certain compromises. I can't drop the RS45 any lower to get a perfect straight shot at the screen without causing problems with viewers' heads casting shadows on the screen.
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kal
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Joined: 06 Mar 2006
Posts: 16032
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 5:15 am    Post subject: Reply with quote

cmjohnson wrote:
It has a huge range of lens shift but in order to run zero keystone and use lens shift to reshape the raster to exactly fit my screen, it would demand that the projector be placed where I can't place it.

You don't have to drop it. I have mine dropped a few inches but still higher than the top of the the screen, and centered horizontally:



My project's above people's heads which is normal. You can walk under it. Zero keystone.

Quote:
Every installation requires certain compromises. I can't drop the RS45 any lower to get a perfect straight shot at the screen without causing problems with viewers' heads casting shadows on the screen.

You shouldn't have to. Nobody does that.

The manufacturers don't expect you to install the projector below the top of the screen. A projector mounted flush with the ceiling but on the center line of the projector will not require any keystone.

Can you tell us more about the setup? Unless you have to shoot from over on one side or something really weird, you shouldn't have to use any keystone.

Kal

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cmjohnson



Joined: 03 Apr 2006
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Location: Buried under G90s


PostLink    Posted: Fri Dec 23, 2016 5:21 am    Post subject: Reply with quote

There's the issue, the RS is mounted UNDER my Marquee, so it's actually too low to run zero keystone. Going above the Marquee is a non-starter, too, because it's within an inch of the ceiling already.
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ecrabb
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Joined: 13 Mar 2006
Posts: 15909
Location: Utah

TV/Projector: JVC RS40, Epson 5010


PostLink    Posted: Fri Dec 23, 2016 7:13 am    Post subject: Reply with quote

cmjohnson wrote:
There's the issue, the RS is mounted UNDER my Marquee, so it's actually too low to run zero keystone. Going above the Marquee is a non-starter, too, because it's within an inch of the ceiling already.


It doesn't matter that it's mounted under the Marquee. If you're having to use any keystone, then it can only be because the projector isn't square to the screen, which has nothing to do with it being under the CRT.

Zero the keystone, rotate projector until the picture is square on the screen, then use lens shift to center the picture on the screen.

It doesn't matter that you're using "only" 2 keystone. 1 click destroys the rsolution. You can see it plain as day if you put a 1:1 pixel resolution pattern on the screen.

Zero keystone. The only way to go.

SC
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hansilili



Joined: 09 Mar 2007
Posts: 302
Location: Köln, Germany


PostLink    Posted: Fri Dec 23, 2016 9:51 am    Post subject: Reply with quote

[quote="ecrabb"]
cmjohnson wrote:


It doesn't matter that you're using "only" 2 keystone. 1 click destroys the rsolution. You can see it plain as day if you put a 1:1 pixel resolution pattern on the screen.

Zero keystone. The only way to go.

SC


Probably yes in test patterns, but not with movie content.

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kal
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Joined: 06 Mar 2006
Posts: 16032
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 2:03 pm    Post subject: Reply with quote

ecrabb wrote:
cmjohnson wrote:
There's the issue, the RS is mounted UNDER my Marquee, so it's actually too low to run zero keystone. Going above the Marquee is a non-starter, too, because it's within an inch of the ceiling already.

It doesn't matter that it's mounted under the Marquee. If you're having to use any keystone, then it can only be because the projector isn't square to the screen, which has nothing to do with it being under the CRT.
Zero the keystone, rotate projector until the picture is square on the screen, then use lens shift to center the picture on the screen.
It doesn't matter that you're using "only" 2 keystone. 1 click destroys the rsolution. You can see it plain as day if you put a 1:1 pixel resolution pattern on the screen.
Zero keystone. The only way to go.

+1 to all of this. Like I wrote previously, unless you're installing the projector off on a side wall or something, there's no reason to use keystone. As long as the projector's positioned anywhere along a vertical line that runs from above the screen to below, you don't need to use keystone. The digital projector can be above the screen on the ceiling or even below on the floor. Doesn't matter. All require zero keystone. Your Marquee is most certainly installed centered on the screen right? So placing the digital immediately below means it can be installed square, with zero keystone used

hansilili wrote:
ecrabb wrote:
It doesn't matter that you're using "only" 2 keystone. 1 click destroys the rsolution. You can see it plain as day if you put a 1:1 pixel resolution pattern on the screen. Zero keystone. The only way to go.


Probably yes in test patterns, but not with movie content.

The same could be said about dowrez'ing 1080p content to 720p. Most people would not be able to tell the difference with movie content, but there's no reason for Chris to NOT set up the projector correctly with zero keystone especially when there's probably no reason why he has to use keystone.

Kal

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cmjohnson



Joined: 03 Apr 2006
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Location: Buried under G90s


PostLink    Posted: Fri Dec 23, 2016 2:35 pm    Post subject: Reply with quote

I will experiment with this. Set keystone to zero and find out if there's a way for me to use lens shift, tilt the PJ, move it around
on its shelf, etc. and try to make it work.

While using keystone might be bad for test patterns, I don't believe it makes a movie unwatchable. Maybe it wouild be if there was a really pronounced screen door effect going on, but at 1080p and this screen size, that isn't a problem.
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kal
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Joined: 06 Mar 2006
Posts: 16032
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 3:39 pm    Post subject: Reply with quote

Like SC said, put up a single pixel text pattern (1 on, 1 off, repeating) and then play with keystone to see how it destroys resolution. It's very telling. You can effectively cut the resolution in half very quickly. If you're ok with 960 pixels across instead of 1920 instead of taking 5 mins to position the PJ correctly, you should have saved your money and bought a $200 digital. Wink

I find it odd that you're always talking about pushing CRT projector technology to eek out every last drop of performance, even begging Moome for a 4K HDMI input card and now you're saying that resolution doesn't matter? Pick a direction please.

Here's a free test pattern disc that has that sort of on/off test pattern - it's a disc that everyone should have in their A/V arsenal: http://www.avsforum.com/forum/139-display-calibration/948496-avs-hd-709-blu-ray-mp4-calibration.html

It's the one I used when setting up my JVC RS56 to better see how any keystone completely screws up resolution.

Kal

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Jeremy112



Joined: 28 Sep 2006
Posts: 2643
Location: Fond du Lac, WI


PostLink    Posted: Fri Dec 23, 2016 4:05 pm    Post subject: Reply with quote

If the PJ is going under the CRT PJ, wouldn't you need to use LESS lens shift than if it was mounted on the ceiling? O.o
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Jeremy112



Joined: 28 Sep 2006
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Location: Fond du Lac, WI


PostLink    Posted: Fri Dec 23, 2016 4:09 pm    Post subject: Reply with quote

kal wrote:
ecrabb wrote:
cmjohnson wrote:
There's the issue, the RS is mounted UNDER my Marquee, so it's actually too low to run zero keystone. Going above the Marquee is a non-starter, too, because it's within an inch of the ceiling already.

It doesn't matter that it's mounted under the Marquee. If you're having to use any keystone, then it can only be because the projector isn't square to the screen, which has nothing to do with it being under the CRT.
Zero the keystone, rotate projector until the picture is square on the screen, then use lens shift to center the picture on the screen.
It doesn't matter that you're using "only" 2 keystone. 1 click destroys the rsolution. You can see it plain as day if you put a 1:1 pixel resolution pattern on the screen.
Zero keystone. The only way to go.

+1 to all of this. Like I wrote previously, unless you're installing the projector off on a side wall or something, there's no reason to use keystone. As long as the projector's positioned anywhere along a vertical line that runs from above the screen to below, you don't need to use keystone. The digital projector can be above the screen on the ceiling or even below on the floor. Doesn't matter. All require zero keystone. Your Marquee is most certainly installed centered on the screen right? So placing the digital immediately below means it can be installed square, with zero keystone used

hansilili wrote:
ecrabb wrote:
It doesn't matter that you're using "only" 2 keystone. 1 click destroys the rsolution. You can see it plain as day if you put a 1:1 pixel resolution pattern on the screen. Zero keystone. The only way to go.


Probably yes in test patterns, but not with movie content.

The same could be said about dowrez'ing 1080p content to 720p. Most people would not be able to tell the difference with movie content, but there's no reason for Chris to NOT set up the projector correctly with zero keystone especially when there's probably no reason why he has to use keystone.

Kal


I thought CRT was supposed to be the complicated projector design, not digital Razz Both Kal & Steve are correct, this isn't rocket science, its a digital PJ, and should take about 10 minutes to align to a screen... properly. Laughing

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garyfritz



Joined: 08 Apr 2006
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Location: Fort Collins, CO


PostLink    Posted: Fri Dec 23, 2016 5:32 pm    Post subject: Reply with quote

The RS-45 has +/- 34% horizontal lens shift. Can't you use that to true the picture without using keystone? Even if you mount the projector off to the side?
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kal
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TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 5:39 pm    Post subject: Reply with quote

Jeremy112 wrote:
If the PJ is going under the CRT PJ, wouldn't you need to use LESS lens shift than if it was mounted on the ceiling? O.o

Correct.

Kal

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Jeremy112



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PostLink    Posted: Fri Dec 23, 2016 5:44 pm    Post subject: Reply with quote

Thought so Kal, thats why I'm not getting why keystone is even needed... Especially since the RS45 has horizontal AND vertical lens shift, basically makes keystone useless.
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kal
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TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 6:13 pm    Post subject: Reply with quote

I imagine they still include keystone for when really whacky side installs are the only option, like this:



Kal

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Jeremy112



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PostLink    Posted: Fri Dec 23, 2016 7:05 pm    Post subject: Reply with quote

kal wrote:
I imagine they still include keystone for when really whacky side installs are the only option, like this:

Image was here

Kal



You know, I have a friend whose projector is installed like that, almost exactly (only on the left side), but even his projector has enough lens shift to get by without keystone. Though some projectors do have really crazy lens shift (I believe his is 50% +/- horizontal, its a VPL-HS51A) which would allow the projector to be placed at the far sides of the screen.

Even with 35% +/- Horizontal, that's still considerably off center from the screen without the need for keystone. As for vertical shift, I'm sure it has plenty, there's usually more vertical shift than horizontal.

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kal
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TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Dec 23, 2016 8:22 pm    Post subject: Reply with quote

Yup. That was the most offset pic I could find. There has to be worse, otherwise the manufacturers wouldn't keep including keystone in the menus. Wink

Biggest reason for including it is that it basically costs them nothing (it's just processing and the algorithms are well understood). So if someone isn't able to get the projector shooting 'true' without it, it's there if you need it as a last resort.

Kal

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cmjohnson



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PostLink    Posted: Sat Dec 24, 2016 12:10 am    Post subject: Reply with quote

I spent some time with it and have not yet found the magic combination of no keystone correction and accurate geometry on the screen. With no correction the image ends up slightly keystoned, but due to the low relative position of the projector, the widest part of the image is the BOTTOM of the screen.

If it can be done, I'll find it.
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hansilili



Joined: 09 Mar 2007
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Location: Köln, Germany


PostLink    Posted: Sat Dec 24, 2016 9:47 am    Post subject: Reply with quote

To visualize the scaling effect of the keystone correction use the moire test pattern of checkemon.exe , a very handy testpattern generator. Yes, the loss of resolution and the colour shift caused by poor convergence (compared to a well setup CRT projector) looks frightening. With a standard flat screen and the JVC in a center position one can and should avoid keystone correction.

In my case, on a curved screen with anamorphic lens, there is a trade off between projector mounting height, geometry pincushion distortion, optical focus and JVC X30 keystone correction. Not easy!

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