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Topic: Image quality at a Cinema & home

Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 07-13-2015 08:05 PM

Christie DXL-60SN.

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001

posted 07-13-2015 08:59 PM

quote: Marco Giustini
IMAX: Last Digital show I saw in a proper IMAX... I could clearly see the pixels, I didn't want to believe that that was the show I had paid for. I believe that was pre-4K conversion but the 18 pounds I gave them for that awful show were for real.

Out of the hundreds upon hundreds of IMAX-branded digital theaters running, currently only 4 of them offer the 4K laser-based projection system. All of the rest are 2K only, roughly HDTV resolution blasted up on a great big, floor to ceiling screen.

quote: Leo Enticknap
You may have seen a poorly mastered DCP (like the one of 2001 that we've been complaining about on F-T pretty much since it came out), with a low bitrate. Or, as Bobby suggests, it might have been that the operators at that theater believed that focus on a digital projector is just a case of "set and forget", and therefore it drifted over time.

The set and forget issue may be a source for the problem, but I still feel some theater operators don't want that pixel grid visible at all and will deliberately dial the image slightly out of focus to hide it. They probably think that makes it look more like film that way.
[Roll Eyes]

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-14-2015 06:04 AM

quote: Mike Blakesley
We use Ushio bulbs here that are warranted for 1000 hours

You must be using the DXL-40SN2 in an NC2000C. One of the problems with NEC is that they have rather poor light efficiency. If with that lamp, the NC2000C's claim of 15,000 lumens is sort of wishful thinking. The other two DLP companies would be running 3KW lamps (DXL-30BAF/L, DXL-30BA/L, CDXL-30, CDXL-30SP) and getting upwards of 1900 hours on the lamp, spending less per lamp and using less electricity doing it. A problem with the NEC is the color it starts with, if one does proper color correction, they tend to be more severe, which results in less light available.

Now can you run your lamp past 1000 hours? Sure can and I know people that run 2 to 3 times that amount! And yes, Ushio's DXL line of lamps have a slow decay. The "L" line of lamps (or Christie's "SP" versions) are even slower decay. Naturally, running past warranty is a game of odds and potential money savings versus damage if the lamp explodes. How many lamp lives would you need to save to make up for replacing the reflector, cold mirror and UV blocker? Note, it is likely that the cold mirror will survive and that the UV blocker will sustain the entire hit. If you can save more than 4 lamp lives before the hit, you come out ahead...providing you keep the reflector and such on site to replace or also factor in the lost shows while you await the replacements. Also, can you replace the reflectors and align everything yourself or do you need a tech to come in for that? It is all a game of odds.

Note, a lot of people with NECs use conventional "cinema" lamps in the misguided belief that they are inherently cheaper (NEC supplies the adapter to use "HS" lamps with the projector). Cinema lamps decay MUCH MUCH faster than their digital counterparts and and they don't start out with as much light either. Their arc gaps are typically significantly wider.

In Leo's case, the DXL-60SN/L should be available now. Unless you are running hard (near the top of its range), it should hold its light output pretty well. But again, with an NEC, you get such poor light per watt. The DXL-60SN/L has a wishful thinking lumen rating of 26,000. The other two DLP companies would actually get over 30,000 lumens for that wattage.

Note, lumen output from all of the projectors are approximate. They all presume the most efficient lens in the most efficient zoom position (typically zoomed to maximum). The most efficient lens is typically one of the ones in the middle of the potential range. So as you tend towards the very short or very long, your actual lumen output is going to go down. If you are using that 1.2-1.8 or 2.4-3.9 throw ratio lens, your light on any given lamp is going to be worse than the person using the 1.4-2.05 or 2.5-3.2 lenses.

And even if someone started out with the proper light on the lamp change, it may decay and cease to be good. I recommend refocusing the lamp within the first month of a lamp change and every month thereafter. You'd be amazed how much more light you can get if you allow for normal "burn-back" and re focus the lamp. The lower you run the lamp the slower it is going to decay. Once you start running towards the upper end of the lamps range, decay will increase exponentially.

Getting the right lamp size is key. You want a lamp that is essentially running at the top of its range and hitting its light levels at the point where it should be changed due to age.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 07-14-2015 10:24 AM

Yes, we are running pretty much at the top of a 6K bulb's range. I can't remember the exact figure, but I think it's 160 amps for the full 6K. After putting a new bulb in and adjusting the reflector for the brightest screen, I need to set it to 145-150 with the beam iris in to get 14ft-L on peak white. By 300 hours-ish, that needs to go up to the full 160. By 400-500, the iris needs to come out or we're not going to get 14ft-l anymore. For the last couple of hundred hours of the bulb's life, we're probably slipping below the 14 a little (even without the iris) and would need to replace that bulb a bit earlier than I'd ordinarily like if we get a studio premiere or other screening where everything has to be up to spec.

Because it's a constant struggle to maintain proper screen brightness in that house (thanks to the combination of a 92-foot throw to a screen that it 54 feet across in scope, and an NEC projector), I've wondered about using 7K bulbs. We do have one at our other theater that we put in purely for 3-D presentations and swap out again immediately the 3-D show is done (we use a 3K bulb there for normal shows). But the cost differential between a 6K and a 7K is huge: the 7K bulbs are only warrantied to 300 hours and they cost a lot more to start with.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-14-2015 10:31 AM

Any reason you can't loose the Iris for the entire life? The NEC normally loses enough light just going through it. And if it is scope that is your issue. THE answer is the Anamorphic lens. It is a 23% light booster for scope.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 07-14-2015 10:44 AM

We have masking on all four sides, so there isn't a lot of difference between the scope and 1.85 image size. 1.85 is probably around 42-44 feet across.

One of my co-workers believes that the iris delivers a very significant increase in contrast ratio, in particular making blacks look richer and giving DCPs that derive from film originals a more "filmy" look to them. I don't know if there's a placebo effect going on in my case (in other words, if I'd been shown the same clip with the iris in and then with it out without ever having been told about it, that I'd feel the same way), but I do agree with him. Contrast is not an NEC strong point either, and with the iris, I do think the picture has a little more punch. However, we're so stretched for light in that screen that we can only really use the iris for the first half of each bulb's service life.

I would guess that the iris costs around 2ft-l, which is what the bulb loses over the first 400-500 hours of its life, running near the upper limit of its designed range.

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001

posted 07-14-2015 11:11 AM

quote: Leo Enticknap
Because it's a constant struggle to maintain proper screen brightness in that house (thanks to the combination of a 92-foot throw to a screen that it 54 feet across in scope, and an NEC projector), I've wondered about using 7K bulbs.

quote: Steve Guttag
Any reason you can't loose the Iris for the entire life? The NEC normally loses enough light just going through it. And if it is scope that is your issue. THE answer is the Anamorphic lens. It is a 23% light booster for scope.

Anamorphic would definitely yield a brighter and more uniform looking image, just using what is being supplied on current 2K DCPs now.

Going the "Super 2K" approach, if the DCP had a 2560 X 1080 master image squeezed in post production to 2048 X 1080 for anamorphic 1.25x projection that would end up delivering a much better looking image on screen than the lower resolution 2048 X 858 standard of what is being passed off as ‘scope now. I know I wouldn’t be complaining as much about soft, fuzzy looking imagery on big screens.

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Ken Lackner
Phenomenal Film Handler

Posts: 1907
From: Atlanta, GA, USA
Registered: Sep 2001

posted 07-14-2015 11:29 AM

quote: Bobby Henderson
For many other theaters, be they fake large format or not, if the projector's optics and alignment is even good enough to reveal the pixel grid on screen it gets dialed slightly out of focus anyway to hide that pixel grid so the image doesn't look electronic.

quote: Bobby Henderson
The set and forget issue may be a source for the problem, but I still feel some theater operators don't want that pixel grid visible at all and will deliberately dial the image slightly out of focus to hide it. They probably think that makes it look more like film that way.

It sounds like you are describing a poor decision made by one (or perhaps a very small group of) installer. It certainly is not recommended practice or standard procedure. Do you have firsthand knowledge of this happening? I have never heard of it happening, been trained to do it, or have done it myself.

quote: Bobby Henderson
And then there is the issue of the perf patterns on the screen. The perf patterns didn't matter at all with film. With digital it does matter. The pixel grid can clash with that perf pattern and create moire. So then there's another reason to consider dialing the image a little out of focus.

I'll grant you that intentionally soft focusing the image would be a way to reduce or eliminate Moiré pattern. Perhaps the lesser of two evils, I believe the better solution is to adjust the zoom. You'd be making the image a little larger and therefore cropping more but losing the Moiré pattern. It's a trade-off.

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 07-15-2015 06:32 PM

I ran "Aloha" here at my location and noticed the poor quality..and to chime in with "JP:World", it was just as bad.

I do have to say that it all goes back to the labwork and how it was all put together.

For, some 2K prints can look awesome, like "Mad Max: Fury Road" - I thought I was running a 4K print since I was shooting it through a 4K projector. Yet, the content was only 2K and the image looked danged sharp on our 65 ft screen.

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001

posted 07-15-2015 07:13 PM

quote: Ken Lackner
It sounds like you are describing a poor decision made by one (or perhaps a very small group of) installer. It certainly is not recommended practice or standard procedure. Do you have firsthand knowledge of this happening?

I haven't been in the booth to see the manager/projectionist deliberately dial the projector out of focus. However, it seems like every theater I visit, including any IMAX-branded digital houses, the projected image just is not sharp. It all looks out of focus. End titles are especially bad; just a big scrolling list of blur.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-16-2015 01:10 AM

I've never seen nor heard of it being proper or desired to make the image out of focus. I've, on rare occasion, zoomed the lens slightly to break up a moire pattern.

Seeing a soft image can be from the lens drifting from its set position. Different projectors have better/worse time hitting their mark but they ALL drift over time and the more you move the lens (e.g. if you always zoom to flat for preshows even on scope movies) you are more likely to accelerate the eventual drift.

As others have noted...if there is a 3D apparatus being used (Real D XL/XL-S) then you are never going to have perfect alignment across the image in 2D and even in 3D for the signal machine "XL". It is a game of making it look as uniform as possible. The more offset the projector is in any direction and if the screen is curved, you ARE going to have double images as you move away from the center.

As for credit scrolls...no DCinema can't do them and it is worse on 2K movies. They do look like a sloppy burry mess. There is just not enough resolution and the gridded nature of the image just interacts to look nasty. You can have a perfectly focused image but when a credit scroll starts... [puke]

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Jonathan Goeldner
Phenomenal Film Handler

Posts: 1360
From: Washington, District of Columbia
Registered: Jun 2008

posted 07-16-2015 11:33 PM

quote: Steve Guttag
perfectly focused image but when a credit scroll starts

never a prob on 35mm ... [Big Grin]

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