Bit off topic ...

I went to a cinema last night that I hadn't been to before, to see Ocean's

  1. We sat about half way up the theatre, so not too close. Both of us commented that the picture didn't look *quite* in focus, although that didn't seem to quite cover it. When the picture stood still though, it was pin sharp. During the advert session, they mentioned that some sporting event or other, was going to be covered live via satellite, which got me thinking that this must be an *electronic* cinema, using DLP projectors. It then occured to me that what we were seeing as being 'out of focus' might actually be motion blur, typical of digital display technology. With this in mind, when I looked even closer, it seemed to me that the picture was not evenly illuminated either - a bit like I see on this widescreen LCD monitor that I'm using here. During the main presentation, a film-stock 'scratch' appeared at the left side of the screen. However, it went on for a long time, and was absolutely dead straight, although it did jump back and forth a bit, but very 'precisely'. Also, it's colour seemed to change with the surrounding content, so if that was black, the 'scratch' would be white, and so on, so I then got to thinking that this might be an error on a line of mirrors on the DLP chip. As we left the cinema, I took a look up at the booth window, as best I could, and there didn't seem to be any film looping around the ceiling that I could see.

So, does anyone out there work on these DLP projectors - either commercial or domestic ? *Was* it one of them that was showing this film ? Are these DLP chips slow enough that you can see motion blur ? Was that 'scratch' typical of a DLP chip problem ? ( it wasn't there at the beginning, and it went away before the end )

Sorry it's a bit OT, but it seemed like an interesting subject, with a potential repair-related angle, and we sometimes have some good discussions on here about such things.

Arfa

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Arfa Daily
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I have a DLP rear projector and it certainly has motion artifacts on some material. It's most noticeable on TV material that is interlaced originally. But then plasma and LCD also have artifacts. You need a decent CRT to avoid them. ;-)

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*I don't suffer from insanity; I enjoy every minute of it.

    Dave Plowman        dave@davenoise.co.uk           London SW
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Dave Plowman (News)

Yes, I've seen that on satellite channels that use a low bandwidth transponder, where the station presumably has to apply severe levels of compression to get the data rate down. These are of course the 'cheapo' stations that can't afford transponders capable of handling high data rates. When you look at stations like QVC which shows very fine detail stuff like jewellery, or the premium movie channels, it's much less noticable. I'm also well familiar with typical motion artifacts that come from both LCD and plasma display technologies. It's the one thing that has stopped me replacing my large screen CRT set so far, whilst I hang on and wait to see what SED has to offer when it finally hits the market. Word is that the drive system required is much less 'digital' than either LCD or plasma, and that the individual SED cells are *much* faster. As a result, these displays are a lot more 'CRT-like', and don't suffer the typical motion artifacts created by the drive electronics.

Going back to the cinema thing, 'motion artifacts' in the way we traditionally understand that term, didn't seem to be what we were seeing. Normally, with 35mm film stock, camera pans appear just as they would with your own eyes, if you were turning your head. The (apparantly) moving scene stays in sharp focus. What we saw on any protracted camera pans, was what appeared to be an annoying shift in focus. No pixellation at edges, or motion trails on bright or saturated areas. Just what looked like a uniform shift in focus over the whole screen. You were actually thinking "boy, my eyes are getting bad". But as soon as the pan slowed to a stop, the focus was back pin sharp again. It's hard to describe, but it was only a few weeks ago when Spiderman came out, that I went to a U.S. cinema - actually one in the Orlando area that's been completely refurbished over the last year - that was using film (you could see it looping round the ceiling through the booth window) and I noticed nothing out of the ordinary, at all. The cinema in my town that I usually go to, also uses genuine film, and I haven't noticed anything wrong worth commenting on there either, so I'm sure it's not just me. Plus the fact that my wife said that she was seeing exactly the same thing, and it was she that made the first comment.

I guess that it might just be the price that we are paying for technological advance, but I sure hope that this part of the technology doesn't now get considered 'mature', and all development efforts go into other areas. I would hate for this to be the future of cinema. In some ways, I think that all the 'digital' hype is a bit of a con. Yes, it allows a lot of good things like being able to cram lots more channels into the band space, eliminating noisy pictures from a poor signal, and ghosting and so on, and the digital display technology allows for slimline sets, consuming less power etc, but with the best will in the world, if we're absolutely honest, the displayed picture doesn't come close to a good CRT set with a good analogue signal going in, and the same seems to be true now of film stock versus digital cinema projection.

Arfa

Reply to
Arfa Daily

Recently helped present the premier of Spiderman 3 at a large convention. The projector was--I believe--LCD, the screen, about

30'x50' (or whatever the correct ratio would be). The film looked great in the Aladdin Performance Theater (Vegas). I don't have a 'film' reference to compare.

I have noticed that sharpness in movie presentation has suffered over the last decade or so. I recall watching Titanic at my local multiplex and being very disappointed at what looked like focus issues, only to see the presentation sharpen up for static scenes.

I think it's just an indication that the art still requires an effort to suspend disbelief. For some reason, I've never experienced an IMAX presentation. I'm afraid I'd be disappointed. Despite all the hype about hi-def TV, I'm still not all that impressed so far.

YMMV

jak

Reply to
jakdedert

That sounds like the same thing on the Titanic show,Jak. I've seen IMAX film presentations, and they are stunning. We've also got some HD transmissions on sat here now and, leaving aside the motion artifacts from the actual display technology, I think that they look pretty good,but I'm not sure that's good enough for me to want to put my hand in my pocket to pay the extra subscription.

Is Alladin's refurb finished yet ? It was still in progress when I was there last year. Are you based in Vegas ?

Arfa

Reply to
Arfa Daily

I noticed on my mates super mega expensive Sony HD giant flatscreen, (which he was enjoying showing off to me using Sky`s HD demo channels), that only the stationary parts of the picture were really sharp, as you say, pans seemed to me to leave a streaky mess and the way the picture seemed to pop back into super sharp focus when the motion stopped, I found disturbing - I wouldn`t have been happy if it had been a 100 quid telly, but as a top of the range state of the art mega expensive piece of kit, I was definitely disappointed. He doesn't seem to notice anything wrong, he`s very happy with the quality.

Ron(UK)

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Ron(UK)

Yes, that's how video compression works. That's where the high data rates are (in the moving bits).

" He doesn't seem to notice anything wrong " is how they sell it.

Graham

Reply to
Eeyore

(in

They wouldn't be selling one to me then!

Ron(UK)

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Ron(UK)

are (in

It's very disappointing.

Quality has been sacrificed so we can have 500 channels of brain-dead blandness.

Graham

Reply to
Eeyore

But I don't see why we should have to endure this at the cinema, where it must be just about distribution costs ( and possibly being able to show some live moronic football or somesuch occasionally ). 35mm film suffers from no such problems, so if they are now using electronic projectors, and this is as good as they're going to get ( coz I guess that the micro-mirrors actually have significant inertial mass, as well as suspension resistance, both of which which will limit the maximum transition speed of them ), then I think that cinema has taken one giant step backwards. It's not as if it's cheap to go. For the two of us, with a bucket of post-mix Coke, that actually tasted like watered down toothpaste died black, and a hot dog that did my stomach no good at all, we got about 20 pence change out of twenty quid. Compare this to the cinema we went to in the U.S. a few weeks back, where the admission was $6.50 each, and that came with a free sack of popcorn and about a gallon of very acceptable Pepsi AND the film was shown from proper 35mm stock ...

I did a quick bit of looking up on these DLP cinema grade projectors, and it seems that the horizontal resolution of the DLP chip is 2k, with a maximum screen width of around 70 feet. that makes pixels in the order of about a half inch, which seems potentially quite big ??

Arfa

Reply to
Arfa Daily

I'd have thought it child's play to make those mirrors move rather faster than a projector shutter. ;-)

Trouble with 35mm film is the cost of the prints and the susceptibility to damage.

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*If you think nobody cares about you, try missing a couple of payments *

    Dave Plowman        dave@davenoise.co.uk           London SW
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Dave Plowman (News)

I have an IMAX here in Nashville. I'll have to brave the crowds some time. I've seen hi-def and not been 'that' impressed. OTOH, I'm comparing NTSC, so your mileage would be different.

The casino has been sold to Planet Hollywood, and is under expansion, but the theater--though attached--is still Aladdin. Very nice facility with VDOSC sound and extensive lighting rig. Despite the quality of the in-house audio, the movie people insisted on bringing their own, consisting of big bass bins with old 4' square JBL constant-directivity horns with a smaller JBL horn mounted coaxially for high end. I think they were concerned that they wouldn't be able to match the surround gear they brought with the house system.

I was working a convention in Vegas. Spidey was part of the entertainment, along with Hall & Oates, Jay Leno and the Blue Man Group.

jak

Reply to
jakdedert

I don't get to movies much, but the last time I took two 10yo's I forbade them to buy goodies as we had just stopped for treats beforehand. They asked if they could at least have a bottle of water, so I thought 'what the heck' and got one for myself as well.

Total cost (just for the water): $10.50.

I don't think the cineplex I usually frequent--and where I saw Titanic--could have been digital as far back as that. It must have been film. I think the issue lies in shooting the CG (computer generated) portions.

I didn't actually ask the resolution, as I had numerous other things to attend; but I did see the light box, which used a 6 kilowatt lamp. The projector was made, IIRC, by NEC. The picture overall was actually superb, but did suffer the issues under discussion. Whether that was in the production or projection, I couldn't say.

jak

Reply to
jakdedert

I feel the same about HDTV for the most part, but IMAX is really something else. There's no comparison between standard cinema and IMAX, it's amazing. Most of the IMAX movies I've seen have not been regular movies but features relating to science and technology.

Reply to
James Sweet

Likewise. There's a good IMAX theatre at the NASA complex in Florida that shows some stunning views of the earth from space, and a particularly impressive sequence containing an 'astronaut's eye view' sliding down the escape wire from the top of a launch gantry. That's an interesting point that Dave P makes above, about the mirrors being faster than the inter-frame shutter on a conventional film projector. I wonder if the difference is that the whole frame is rapidly blanked each time, then snapped back on as a whole frame with the new-position in the pan, as opposed to 'waves' of micromirrors moving *with* the pan. Perhaps the human eye is better at integrating these individual whole-frame pictures, than it is at doing the same for pixel-level movements at such a large size - if you see what I mean ... Maybe, it's something to do with the different colour and monochrome resolutions of the eye. Now that I'm thinking about this a bit more, perhaps it's a combination of the speed of the movement, AND the size of the screen AND how close you are sitting. Perhaps there are combinations that show the problem worse. Next time I go to this same cinema, I'll try sitting in a different place, and maybe taking my glasses as well, just to see if it makes any difference to place some optics in front of the eye.

Arfa

Reply to
Arfa Daily

blandness.

formatting link

second strip down...

Ron(UK)

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Ron(UK)

On 17 jun, 01:41, "Arfa Daily" wrote: , I think that

I hear what you're saying Arfa. bit do the displays you mention really consume less power'? In the case of the plasma sets in particular you'd have to go back to the early 70s valve colour tvs to find anything approaching their wattage consumption! so much for progress and ecology. instead of ranting on about not leaving sets on standby, they should bring in laws against this modern cr@p!

I think at least in the Uk, what has been done to broadcasting is a disgrace. Sell everyone flat screens with awful artefacts especially on tv reception, then use that as an excuse to phase out analogue and also prepare the ground to sell HDTV.

Reply to
b

Yes, you're right, the plasmas, at least, do consume a lot of power. I don't think that the LCDs are too bad - I haven't really looked to be honest, but I seemed to think that low power consumption was a 'selling point', although this could be just sales hype; I suppose it depends what you're comparing it to. I agree with what you say about broadcasting in the UK, although I think that the whole situation is a lot more political than just phasing out analogue in preparation for HD. The government stands to make billions selling off spectrum space to rich users like cellphone companies, just as soon as they can drive all the existing users off. 470 to 860 megs give or take a bit of 70cms amateur space and a few other users between bands IV and V, is an awful lot of spectrum to be able to put up for auction, if you can make the new users co-exist with the originals by making it all digital ...

We are heading back for the old days of band III TV in terms of ironwork on the roof now. We had got it down to nice neat little 10 ele yagis for the most part. Now, in order to receive the crap digital signals - which let's remember are, according to Monkey on the TV adverts, going to be dead easy to receive just by plugging into a set top box - you need a 650 element triple reverse co-phased crossed dipole anti-ghost log periodic about 6 foot long and with a bloody great cake-cooling rack on the back ! Cost to install ? Oh, only about 180 quid ...

And let's not forget, as most people seem to have, or have not really understood in the first place, every little portable in the kitchen, conservatory, kids bedroom, garden shed, and every VCR, analogue DVDR, PVR etc, is going to need yet another 30 quid STB ...

Arfa

Reply to
Arfa Daily

and

honest,

stock

The driving force is the sell off of much of the then released UHF "airspace" - talk of intangibles, how many billions was that "commodity" sold for ?. So people can drive their cars watching films via the extra bandwidth to their mobile phones - brilliant.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

formatting link

Reply to
N Cook

When analogue is switched off the power of the digital transmitters will increase - you can't do this at the moment due to co-channel interference. Then the same size aerial should suffice. Most of the population can already get FreeView with their exisiting aerial - if they had good analogue reception. But like many things digital it doesn't degrade gracefully. There are some locations where some 'analogue' aerials aren't suitable for the different frequency digital - but pretty rare. I realise this doesn't help those in a poor signal area, though. But I'm 'OK Jack'. I can see the London transmitter out of the window in this room. ;-)

--
*I took an IQ test and the results were negative.

    Dave Plowman        dave@davenoise.co.uk           London SW
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Dave Plowman (News)

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