Lumens vs screen size vs distance vs mild panic - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 11 Old 09-22-2017, 07:20 PM - Thread Starter
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Lumens vs screen size vs distance vs mild panic

Hi guys, I'm completely rebuilding a building in my back yard. It's going to have a theater section that I'm obviously very excited about. I'm undecided on projector model so far, but leaning towards sony's 4k and I don't think I can afford > 10k for a projector. Obviously I'm interested in the new 85 models introduced at CEDIA also peeking at JVC's offerings. I'm sensitive to RBE and would be really disheartened to spend a load of cash on a projector and see that all the time, so I'm pretty set on LCoS.

What I am decided on (I hope) is my screen solution. I want to install a 12' x 5' 2.40:1 AT screen that gets masked off on the sides for 16:9. Using lens memory to zoom between formats (ie. no anamorphic lens setup) I grew up working in a movie theater, and am a Gaffer / Cinematographer by trade, so I'm very sensitive to overall image quality including hotspot, sparkies, RBE etc. so I figure I'll have to stick with a gain no greater than 1.0.

The space will be completely light controlled with black ceiling and dark grey walls / carpet. The projector will be in a "booth" behind the viewing room (above adjoining room) with a lens to screen distance of just over 17'.

What's got me concerned is the projector calculator on http://www.projectorcentral.com/
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Putting my size and distance number in results in the calculator for the new Sony 385ES gives a warning about screen brightness. It suggests I'll end up with 10 FL. And the JVC doesn't fare much better. Am I completely out of touch with the abilities of this level of projector? would i end up with a bland image with this setup?

I've read around and I'm finding recommendations of 12-16 fL, and those all seem to be traditional thinking. Now with HDR and more color space, I'm assuming that a projector would need to be capable of even more brightness to allow for a greater dynamic range overall.

Here is a crummy view from my sketchup to give an idea of the space.
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SO on to the advice I seek:

Am I trying to eek too much out of a < 10k projector to have 12' wide screen with projector 17+ft away?

I could build the projector booth closer to the screen, (inside the theater space) but that creates a whole host of problems that are easily solved with it where its currently planned.

Am I using the projector central calculator wrong, or putting too much stock in it?

Do i just need to pony up and get a projector w/ more lumens?


Thanks for any help, I hope to start a build thread soon, as I think this will be a pretty interesting project. We are building inside an existing concrete block building, adding stud walls inside, and making the whole thing taller, then covering the outside with stucco. I'm hoping for a pretty well isolated theater when it's all said and done. Just for entertainment, here's a time lapse from the day we poured some new foundation and slab to extend the "kitchen" nook.
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post #2 of 11 Old 09-23-2017, 06:12 AM
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You have a big screen and a low gain AT screen. One solution is to use a higher gain micro perf screen. I've installed a JVC on a 150 inch wide screen (1.0 gain) it isn't as bright as others but it brought a smile to the customer. I'm sure there are others who have gone with less than 12 ft lamps and are happy, personally I like brighter.
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post #3 of 11 Old 09-23-2017, 06:19 AM
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If you have the money you could also invest in the new Panamorph vertical compression lens. Stretch your image to the full chip height and then squeeze to fit the screen. You gain brightness.
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post #4 of 11 Old 09-24-2017, 08:21 AM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post
If you have the money you could also invest in the new Panamorph vertical compression lens. Stretch your image to the full chip height and then squeeze to fit the screen. You gain brightness.
Thanks for the thoughts, I would love to have an anamorphic lens setup, but if the MSRP is to be believed on Panamorph's site, that would add another 10K by the time i got a lens and transport rail to slide it out of the way for 16:9. If I could afford that, wouldn't it make more sense to spend 2x on a brighter projector and not deal with the challenges of projecting through an external lens?

Also I'm not sure if it's changed in the x85 Sony PJs, but there is a note on Panamorph's site (a small one) that says 4k content can't be resized to work with their lenses on Sony PJs, so it would only work with HD content.

Starting to feel like I'll have to choose between giving up;

1. Having CIH with Anamorphic being the "biggest" format. I really like wide movies, and I prefer that they are the most involving, impressive experience.

or

2. Having a smaller screen overall. Reducing the size of 2.4:1 from 12' wide makes such a drastic change to the 16:9 image fitting on the same height screen, that it starts to hurt quickly. Going down this path I'd likely want to also abandon the CIH idea, and end up with a screen ratio that is either somewhere in between the two formats, with 4 way masking (manual) or I've seen a couple threads with multiple screens to allow for a best of both words approach. While I'm not totally opposed to two screens, its got a few drawbacks to me (cost, redesign of screen wall, etc)

Another consideration would be to buy a 1080p projector that has the lumens to fill the screen size I want, and upgrade to 4k down the road when the prices / performance match my desires, but I really hate buying things twice, selling things, etc., it always feels like a loss to me. Perhaps a used projector could be a stop gap for me...
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post #5 of 11 Old 09-24-2017, 10:11 AM
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I'd choose option 2, moving the chairs closer to the screen, but I'd keep the screen 2.4 ratio.

A 120 or 130'' widescreen wouldn't be as impressive when entering the room, of course, but as soon as you start watching a movie you'd quickly forget that the screen is slightly smaller than planned. And most important of all (at least to me), 2.4 widescreen movies would be bigger than 1.85 and TV content.
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post #6 of 11 Old 09-24-2017, 05:17 PM
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I am sure this isn't a preferred approach, but you *could* physically move the projector into the room, physically closer to the screen, in addition to slightly reducing the size. Both will help tremendously.

I know you said you are sensitive to hotspotting, but a Stewart 1.3 gain screen will also help you maintain the size you are looking for.
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post #7 of 11 Old 09-24-2017, 07:01 PM
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he is already at nearly the closest position for that size screen.
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post #8 of 11 Old 09-25-2017, 04:49 AM
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Quote:
Originally Posted by lukewayne View Post

Putting my size and distance number in results in the calculator for the new Sony 385ES gives a warning about screen brightness. It suggests I'll end up with 10 FL. And the JVC doesn't fare much better. Am I completely out of touch with the abilities of this level of projector? would i end up with a bland image with this setup?
I don't know what numbers you put into the calculator, but a 144" wide image is 81sf of screen area. 81x16fl means you would need 1300 lumens at 1.0 gain. I can't find a review of the true calibrated brightness of the Sony 385, but the 365 calibrated to 1350 lumens in reference mode at ProjectorReviews.com. That is a pretty thin margin for 16fl, but it is much better than the 10fl that concerned you. The ProjectorCentral calculator is notoriously inaccurate in its brightness numbers.

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post #9 of 11 Old 09-25-2017, 04:10 PM
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Quote:
Originally Posted by BIGmouthinDC View Post
he is already at nearly the closest position for that size screen.
Could mean a 2ft lambert difference when advanced just a foot or two, depending on the projector and lens system.
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post #10 of 11 Old 09-25-2017, 05:25 PM
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he can only move it 11 inches and I wouldn't plan to place it within 6 inches of the lens limit.

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post #11 of 11 Old 09-25-2017, 05:58 PM
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I was pulling the JVC as the other option. It can go closer.


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