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VideoGrabber
Joined: 09 Apr 2006
Posts: 933
Location: Michigan
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| Posted: Fri Jul 16, 2010 11:00 pm Post subject: |
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| greg_mitch wrote: | I was super psyched about the AE4000 but spending just a few nights in the CIH forum over at the A*site gives me the understanding that most CIH diehards put up their nose at zooming for CIH.
I just can't quite wrap my head around paying $2000 for a projector and another $2000 for a lens...there has to be a better way.
I was almost set on getting an AE4000 and then "slumming" it by zooming to see if I would care...but now I don't know. |
Greg,
first off, Dave hasn't been back in here yet, but I think he'll tell you that it's not necessary to spend another $2k for a lens.
With that out of the way, the idea of using powered zoom, with memories, appeals to me a lot more for CIH. At the risk of telling you things you already know, the downsides to zooming are light output and light spill.
Starting with the spill factor, I'm not sure how light-absorbent your screen wall is, but any minimal amount reflected will show up when you're in scope mode (above and below the screen). This will be worsened perceptually if you're using a PJ with a DI. You'll see the surrounding area "pumping" with residual background light intensity. The problem isn't intractable if you can disable the DI (and live with the results), or completely soak up the excess light, so it's not a distraction. The other trick that can sometimes be used is masking, at the PJ, which will allow you to use a DI without seeing the side-effects. (Of course, that then involves manually inserting/removing something from the light path, every time you switch to/from scope.)
I'm sure you know the brightness will drop when you switch to scope mode. You take a double hit there, because you're not only using less of the imaging area to generate light, but then you're stretching it out to fill a larger area. This can be compensated for in a couple ways, depending on how much output your PJ has, and the size/gain of your screen. If you have lumens to burn, you can pop a neutral-density filter on the lens when in 1.78 mode, and remove it in scope. Alternately, if the low output mode from your bulb is adequate in 1.78 mode, you could switch to high output when going to scope.
Just because you decide to try zooming instead of an A-lens doesn't mean you're "slumming it". There may be a small price to pay (which you can minimize), but there are always going to be compromises in any configuration. (E.g., Unless you spend boo-koo bucks on an A-lens, you're going to have to live with chroma aberrations.) Once you've implemented those, if you're still disappointed and decide that long-term it's not going to satisfy your quality criteria, you can ask Dave where to get an A-lens for $700, and start saving up for it. OTOH, you may decide that you're already very happy with the net results, even if they're not completely "perfect".
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- Tim
Last edited by VideoGrabber on Fri Jul 16, 2010 11:18 pm; edited 2 times in total
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Fri Jul 16, 2010 11:13 pm Post subject: |
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You have to have screen masks for every projector - especially CRT with it's crappy ansi contrast.
I've always had masks, started 10 years ago when we used to borrow a terrible LCD from a friend's work, and then built an adjustable system for my 1251.
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VideoGrabber
Joined: 09 Apr 2006
Posts: 933
Location: Michigan
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| Posted: Fri Jul 16, 2010 11:21 pm Post subject: |
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Mark,
true, but unless he has masking that goes quite a way above and below the screen, he could still have an issue with zooming. You can have effective masking, yet not have wall-to-wall and floor-to-ceiling coverage.
_________________
- Tim
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Fri Jul 16, 2010 11:28 pm Post subject: |
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I'm pretty close to that 
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huggy
Joined: 02 Aug 2008
Posts: 927
Location: Melbourne,Australia
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| Posted: Sat Jul 17, 2010 12:07 am Post subject: |
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Just a noob question 
If say I'm getting 10 ftl on a 120" 16*9 screen.By zooming out to scope I lose about 30% brightness,so in fact at full scope which is about 12ft wide I'd be getting about 7ftl?
So in turn by adding a lense and using the full panel which is an extra 30% brightness added,the brightness loss at full scope is cancelled out by the lense/full panel addition which adds 30% brightness.This gives me 10ftl at 12ft scope?
Am I wrong in my calculations or am I missing something? I would love to go wall to wall 12ft scope with a digital as blending/stacking is beyond my technical know how.
Dave
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Sat Jul 17, 2010 12:23 am Post subject: |
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Dave, from what I have seen the lens itself will lose a significant amount.
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HogPilot
Joined: 21 Jan 2010
Posts: 2383
TV/Projector: Vizio P702ui-B3, Pioneer Elite Pro-151FD & 111FD
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| Posted: Sat Jul 17, 2010 12:30 am Post subject: |
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| Mark_A_W wrote: | | Dave, from what I have seen the lens itself will lose a significant amount. |
There's plenty of measurements of quality lenses that indicate that light loss due to introducing an anamorphic lens into the light path is minuscule at best. Unless you have dirty or poor quality glass, you get an effective light gain of 30% by using a lens.
_________________
| ecrabb wrote: | | Curt Palme wrote: | | Interesting, Mac isn't returning my emails. Go figure. |
He's mad at us for making Hog a moderator. He took his ball and went home.
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Sat Jul 17, 2010 12:47 am Post subject: |
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Guess that depends how much you spend - the Aussie Morphic lens I saw (Mk2 maybe? Not the latest one.) was terrible.
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huggy
Joined: 02 Aug 2008
Posts: 927
Location: Melbourne,Australia
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| Posted: Sat Jul 17, 2010 1:06 am Post subject: |
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The MK 4 is over 2k,the Isco III which probably has no light loss is just too insanely expensive for me.
It's actually cheaper I think to do it with CRT's on a 12 ft wide screen,but who ( apart from Athan) can be bothered with that?
Dave
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greg_mitch
Joined: 03 May 2006
Posts: 5320
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| Posted: Sat Jul 17, 2010 1:14 am Post subject: |
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| Mark_A_W wrote: | | Guess that depends how much you spend - the Aussie Morphic lens I saw (Mk2 maybe? Not the latest one.) was terrible. |
That CAVX guy gets under my skin in the CIH forum for some reason...I can't put my finger on it.
| videograbber wrote: | | Starting with the spill factor, I'm not sure how light-absorbent your screen wall is, but any minimal amount reflected will show up when you're in scope mode (above and below the screen). This will be worsened perceptually if you're using a PJ with a DI. |
I just rebuilt my screen wall and was going to be putting some sort of manually adjustable velvet panels for side masking and then velvet top and bottom (floor to ceiling) to hopefully eliminate any of this spill factor. I guess we will have to wait and see...Need to save a bit more and play it smart with money for a bit more...
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Sat Jul 17, 2010 10:20 am Post subject: |
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| huggy wrote: | Just a noob question
If say I'm getting 10 ftl on a 120" 16*9 screen.By zooming out to scope I lose about 30% brightness,so in fact at full scope which is about 12ft wide I'd be getting about 7ftl?
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Depends on the zoom lens and whether or not it holds a fixed aperture (like a prime lens for an SLR), or if the aperture changes across the zoom focal range.
| Quote: |
So in turn by adding a lense and using the full panel which is an extra 30% brightness added,the brightness loss at full scope is cancelled out by the lense/full panel addition which adds 30% brightness.This gives me 10ftl at 12ft scope?
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Yes, because you vertically stretch the 2.37 content area across the 1.78 panel and the A-lens horizontally stretches it back out.
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Am I wrong in my calculations or am I missing something? I would love to go wall to wall 12ft scope with a digital as blending/stacking is beyond my technical know how.
Dave |
Not all projector lens assy have the same aperture and the loss as a function of zoom used can be quite different from projector to projector.
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Trust no one. Absolutely no one. Advice of the board.
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HogPilot
Joined: 21 Jan 2010
Posts: 2383
TV/Projector: Vizio P702ui-B3, Pioneer Elite Pro-151FD & 111FD
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| Posted: Sat Jul 17, 2010 11:25 am Post subject: |
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| Mark_A_W wrote: | | Guess that depends how much you spend - the Aussie Morphic lens I saw (Mk2 maybe? Not the latest one.) was terrible. |
What were you using as your frame of reference? If you were simply comparing the 16:9 image with no lens in place to a 2.35:1 image with the lens in place, then yes the latter will look dimmer because you're spreading the same amount of light over a larger area. However, even the MK2 had decent optics and would cause only minimal light loss.
_________________
| ecrabb wrote: | | Curt Palme wrote: | | Interesting, Mac isn't returning my emails. Go figure. |
He's mad at us for making Hog a moderator. He took his ball and went home.
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huggy
Joined: 02 Aug 2008
Posts: 927
Location: Melbourne,Australia
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| Posted: Sat Jul 17, 2010 12:37 pm Post subject: |
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Wan
If I'm understanding you correctly, the combination of lens and/or projector plays a significant part in the amount of light lost when the image is stretched.
So how does one determine the most cost effective solution say for a 12ft wide scope setup as I'm intending to do?
That is of course without sacrificing pic quality.
Dave
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Sat Jul 17, 2010 2:24 pm Post subject: |
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So Dave....what will you do with the 1209s?...
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HogPilot
Joined: 21 Jan 2010
Posts: 2383
TV/Projector: Vizio P702ui-B3, Pioneer Elite Pro-151FD & 111FD
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| Posted: Sat Jul 17, 2010 3:23 pm Post subject: |
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| huggy wrote: | Wan
If I'm understanding you correctly, the combination of lens and/or projector plays a significant part in the amount of light lost when the image is stretched.
So how does one determine the most cost effective solution say for a 12ft wide scope setup as I'm intending to do?
That is of course without sacrificing pic quality.
Dave |
I believe what he's getting at is the fact that most digital projectors don't maintain a constant aperture when you zoom in or out, and therefore the light output for a given image size actually is variable depending upon how much zoom you use. For example, if a given projector can throw a 100" image from between 12' and 16' depending on how much zoom you use, you'll get more light output if you use maximum zoom and mount it at 12'; you'll get more contrast when you use minimum zoom and mount it at 16'. As Wan pointed out, this trade off between light output and contrast due to zoom varies based on the design of the projector optics, so the only way to know how much light output will vary from one zoom extreme to the other is to read a review at a site such as cine4home.de or to buy one and perform measurements yourself.
That being said, there are bigger considerations that you need to look at prior to deciding whether or not you want to use a lens or zoom. Firstly, how light controlled is your room - complete bat cave, mostly with curtains, or not very much? This will help determine how many lumens you need coming off of the screen. You can use a projector with a lower calibrated lumen output if you use something like a DaLite High Power screen (gain of 2.4). However that does restrict the placement of your projector and the width of your seating area because of how the screen works. If you're looking at a normal unity-ish gain screen, your projector options narrow considerably (unless you have a budget well in excess of $20K) because of the lumens required to light up a 12' wide 1.0 gain scope screen. An IN83 would probably be one of the few sub-$10K choices out there that can put out a sufficient number of calibrated lumens to do this.
When considering whether to use an anamorphic lens or zoom, there are two primary concerns - seating distance (which affects pixel structure visibility) and lumen requirements. Depending upon your seating distance, zooming may make pixel structure noticeable with a 2.35:1 image where it's not with a 16:9 image. Also, as you already pointed out, you will experience a drop in ft-lamberts when zooming to a scope image, and depending on how many lumens you have to spare, this may or may not put you below your personal threshold for an acceptable image. An anamorphic lens will allow you to continue to use all the light coming off of the panel and give you a noticably brighter image. As long as you get a good lens - CAVX's MK3 or MK4, Panamorph's UH380 or UH480, Prismasonic's HD-5000, or just about any offerings from Schneider/ISCO - light loss due to scatter within the lens is essentially nil, which I can't emphasize enough.
As an example, let's say that you have a Panny AE-4000 in a completely light controlled room with a brand new bulb, calibrated to D65, projecting onto a 1.0 gain 12' scope (2.35:1 for this purpose) screen. Cine4home's measurements indicate that, at max zoom (projector closest to the screen), you get 950 lumens; at minimum zoom, you get 700 lumens.
Let's start with the zoom method. Given the above conditions, you'll want to maximize your light output for your zoomed scope image, which means you'll have the projector set up so that it fills your scope screen at max zoom, and that you have to decrease zoom to attain a 1.78:1 image. Because of this - and assuming a linear light loss going from max to min zoom - you'll put out 950 lumens at full zoom (scope), but only 887 lumens at 3/4 zoom (1.78:1). However, because you're not using 25% of the panel for scope, you only end up with 712 lumens. This results in an 11.6 ft/L scope image, and 19.1 ft/L 1.78:1 image.
Now let's use an anamorphic lens. In this case, you'll want to set the projector up so that you maximize light output for your 1.78:1 image. You get the full 950 lumens for your 1.78:1 image, resulting in 20.5 ft/L. Introduce the anamorphic lens into the image, and you stretch those same 950 lumens to fill your scope screen, and you have a 15.5 ft/L image. As a side note, you'd have to incur a 25% light loss in the lens to drop to the same ft/L that you'd achieve by zooming; at most you'll incur a 1%-2% loss by using the optics I listed above. Even something like HTIB won't even approach 25% light loss due to internal scatter and retroreflection.
I won't touch as much on the pixel visibility matter as that depends on visual acuity and preferred seating distance, both of which vary greatly from person to person. It also depends on the projector optics and image device tech as well (i.e. DLP vs LCoS vs LCD). Just remember, the closer you sit and the better your eyes, the greater the chance you'll see pixel structure with a zoomed image.
Keep in mind, all of these figures are based on a brand new bulb - you'll want to plan for 33%-50% light loss by the 500 hour mark in the bulb. Also, using a higher gain screen will multiply the figures above by the gain of the screen, assuming you're within the "sweet spot" for that screen. Personally I'd take an IN83 with its significantly higher calibrated output (1400 D65 lumens with bulb on high) coupled with a unity gain screen over the Panny 4000 with say a High Power screen.
_________________
| ecrabb wrote: | | Curt Palme wrote: | | Interesting, Mac isn't returning my emails. Go figure. |
He's mad at us for making Hog a moderator. He took his ball and went home.
SC |
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Sat Jul 17, 2010 7:43 pm Post subject: |
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Thanks, Hog, you hit the nail on the head. Huggy, I am by far someone you should be talking to in your search for the final solution. I am in the same boat as you, and continue asking fellow owners who own the same projector I just bought. I am yet undecided on scope (2.35/2.4) or widescreen (1.78), and undecided on AT or not.
And I probably will not make a determination until I plug this RS20 in and start projecting onto a faux screen and try to get a human idea of how bright it can be. Lucky for me my eyes are very, very sensitive to light (yes, I can see, walk, and read in the dark--wife hates me). This may mean I could easily stand a lower lumen setup that might be better afforded by a 10-12' wide 2.4 aspect AT screen.
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Trust no one. Absolutely no one. Advice of the board.
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huggy
Joined: 02 Aug 2008
Posts: 927
Location: Melbourne,Australia
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| Posted: Sat Jul 17, 2010 10:48 pm Post subject: |
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Wan keep us updated with your progress.
Hog
What can I say? that was one long and very informative post,a must read for anyone really! Thanks for taking the time to compose this as it's just answered every question in my empty head
Mark
1209s is staying put, I have this itch to go scope and the CRT's just aint gonna make that happen. I'm going to keep both and see which is preferable in the long run.This isn't happening anytime soon mind you, I'm just testing the waters ATM so when and if something good comes up I'm ready to pounce.
Dave
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Wed Aug 18, 2010 4:59 pm Post subject: |
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| huggy wrote: | Just a noob question
If say I'm getting 10 ftl on a 120" 16*9 screen.By zooming out to scope I lose about 30% brightness,so in fact at full scope which is about 12ft wide I'd be getting about 7ftl?
So in turn by adding a lense and using the full panel which is an extra 30% brightness added,the brightness loss at full scope is cancelled out by the lense/full panel addition which adds 30% brightness.This gives me 10ftl at 12ft scope?
Am I wrong in my calculations or am I missing something? I would love to go wall to wall 12ft scope with a digital as blending/stacking is beyond my technical know how.
Dave |
You are pretty much on the right track. But as said, the lens eats up a bunch. Between my lens and the increased area I actually have about a 40% drop in brighness. On my current almost 10 foot wide screen my reasonably bright (true 385 ANSI Lumens) PJ is just a bit brighter on a 1.1 gain screen than my 8" CRT was on a 1.2 gain 7.5' wide 16:9 screen.
Going to high brightness mode mostly fixes it, but puts the fan noise at higher than desired levels--not quite 1291 levels, but bad enough you don't want to sit near it.
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Dave
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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