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does it make sens?


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#1 Delorme Jean-Marie

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Posted 26 June 2005 - 01:13 PM

hi i have a theorical question for you
does it make sens to compare 4K HD and film (large format, 65mm) with a 7K digit.
if the final product has to be screened with the best ever projection system at an imax dome (for exemple)
does this kind of test make sens according to your experience?
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#2 John Pytlak RIP

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Posted 27 June 2005 - 01:19 PM

hi i have a theorical question for you
does it make sens to compare 4K HD and film (large format, 65mm) with a 7K digit.
if the final product has to be screened with the best ever projection system at an imax dome (for exemple)
does this kind of test make sens according to your experience?

<{POST_SNAPBACK}>


AFAIK, any "Digital Intermediates" being used for 70mm large format productions are being scanned at GREATER than 4K resolution, including IMAX "DMR" productions being shot on 35mm color negative film (e.g., "Batman Begins").

The team headed by Kodak image scientist Dr. Roger Morton published several SMPTE papers showing the advantages of using 4K scans or greater for fully capturing all the information on a 35mm camera negative.
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#3 David Cox

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Posted 27 June 2005 - 03:03 PM

For CGi originated projects, 5.6K is occasionally used which gives a resolution of 5488 x 4096 pixels. Companies "doing it on the cheap" use a lower resolution and up-res! However, the creation of digital material usually needs a lower resolution than that needed to digitise film, as film also has random artefacts (grain) that needs to be kept in order. So you should probably use that resolution as a minimum.

RPS film imaging in the UK (rpsfilmimaging.co.uk) can print back to 65mm at resolutions of up to 8K. I'm not sure about scanning though.
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#4 Delorme Jean-Marie

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Posted 27 June 2005 - 04:31 PM

verry interesting answers thank you
but my concern is definatly what is the best filming format and postproduction for a 4000 X 4000 pixels minimum on a video projection system on an imax dôme.
theire might be several solutions (i hope) but in term of filming formats what is the scale of quality :
is it
digit of 65mm in ?K ?
35mm DMR process but i do not what to go back to a positiv
dalsa 4K
Viper 4K
if you had no problem with the budget but the best video image to project what would you choose?

david i do not catch the "doing it on the cheap" trick
and film can be shot and processed with a concern of "grain zero" isn't it john?
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#5 John Pytlak RIP

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Posted 27 June 2005 - 09:05 PM

A 65mm 15-perf negative will give the best quality (Format size DOES matter). 65mm 8-perf is also a viable producton format. Even 35mm full frame Super-35 can yield an excellent large format image, especially with digital processing like IMAX DMR. 8-perf 35mm VISTAVISION is also an alternative that would offer a grain advantage over 4-perf 35mm.
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#6 Delorme Jean-Marie

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Posted 28 June 2005 - 12:33 AM

" (Format size DOES matter)"
i 100% agree with you but with large formats we have a fantastic film support but terribles optics, nothing in the range (primo, cookS4, or master prime)
and i'm also concern about a possible digit.
there might be a combo for the best result (15/70) might be to good for exemple
maybe the best solution is around vistavision with master prime with a 5.7K Digit after a pull down process?? that's the kind of solution i'm thinking about.
but before going trhue expensive tests, what is viper, c-mos and DAlsa comparable to in film resolution wise????
thank you in advence
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#7 David Cox

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Posted 28 June 2005 - 01:59 PM

" (Format size DOES matter)"
i 100% agree with you but with large formats we have a fantastic film support but terribles optics, nothing in the range (primo, cookS4, or master prime)
and i'm also concern about a possible digit.
there might be a combo for the best result (15/70) might be to good for exemple
maybe the best solution is around vistavision with master prime with a 5.7K Digit after a pull down process?? that's the kind of solution i'm thinking about.
but before going trhue expensive tests, what is viper, c-mos and DAlsa comparable to in film resolution wise????
thank you in advence

<{POST_SNAPBACK}>


The 4K cameras you are referring to are not really suited to Imax applications. The reason is two-fold. Firstly when they say "4K" they are not talking about vertical resolution. They are referring to the horizontal resolution (a usable number is normally 4046 pixels) but the vertical resolution is designed for either 1:1.85 or 1:2.35 "normal" cinema applications. So at best the resolution is 4k x 2k.

The second reason is that as yet, I don't think anyone has come up with a sensible solution to record 4k x 2k uncompressed images. Thats a lot of data that comes out of the camera very fast!

So if budget is not a problem, 65mm film will give the best result. If you need to do a digital intermediate (very few Imax films have done because of the complexity and expense) then scanning to 5.6K would be desirable, followed by printing back to a slow (low grain) stock. Shameless plug - we can do any resolution DI's!

If budget is more of an issue, then you could do some tests with a Dalsa Origin. If you shot 4K, you might have to do an interpolated blow up to 3x resolution for Imax. My guess is that it would be sort of fine - although perhaps soft compared to a 65mm test. Worth a test if you're budget is too tight.

David Cox
Baraka Post Production
www.baraka.co.uk
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#8 Delorme Jean-Marie

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Posted 28 June 2005 - 04:55 PM

thank you david for your post.

[/QUOTE]The 4K cameras you are referring to are not really suited to Imax applications
my link to imax technologie so far in this project is only the syze of the screen because the projection system i'm asked to use is only a barco system.
So i absolutly do not need a positive.
what can be my best way to film :
film stock or HD
excuse me in advance i the answer is in your previous post and if i didn't catch it.
thanks again to this comunity sharing it's knoledge, i hope i'm not abusing with all my questions.
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#9 David Cox

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Posted 28 June 2005 - 05:56 PM

[quote name='frenchAC' date='Jun 28 2005, 10:55 PM']
thank you david for your post.

[/QUOTE]The 4K cameras you are referring to are not really suited to Imax applications
my link to imax technologie so far in this project is only the syze of the screen because the projection system i'm asked to use is only a barco system.
So i absolutly do not need a positive.
what can be my best way to film :
film stock or HD
excuse me in advance i the answer is in your previous post and if i didn't catch it.
thanks again to this comunity sharing it's knoledge, i hope i'm not abusing with all my questions.

<{POST_SNAPBACK}>

[/quote]

Okay - so you are projecting to a big screen but not Imax? Do you know what resolution the Barco projector can take as a maximum? If its maximum is HD (1920 x 1080), then you would be best off either shooting 35mm and post producing / delivering HD for the best quality, or shooting HD with a good digital cinema camera such as a Sony F950, Thompson Viper or (if you can get hold of one) a Panavision Genesis. Use HD CAM SR as the recording format in RGB - the SRW1 field recorder has the lowest compression ratio. The film route with a good telecine would give you the best quality, although at a slighty higher price.

Check what resolution your Barco can handle. If it says it's 2K, remember that this relates to horizontal not vertical resolution. Their 2K projectors have a resolution of 2048 x 1080. This is very close to the 1920 x 1080 that HD is, and I would suggest that those extra 128 horizontal pictures won't make so much difference that it justifies all the extra work that creating a non-standard "video" stream entales.

If your barco can take a higher resolution, there are ways to create a higher resolution system. However, the difficulty comes from finding a playback method that can support higher resolutions. For example, HD is the highest resolution tape based solution, so you'll need to look at disk playback. So if your barco can take a higher resolution (perhaps through its computer display input), the process would be to shoot either super 35mm, or possibly 65mm if your screen (and budget!) is really big. Then have them either telecined or scanned at the highest resolution your barco will take to files on disk. From these you can make your programme and create a final file - such as a quicktime, AVI etc that runs from the disk system.

What Barco projector are you using?

Regards

David Cox
Baraka post Production Ltd
www.baraka.co.uk
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#10 Michael Most

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Posted 28 June 2005 - 07:03 PM

but my concern is definatly what is the best filming format and postproduction for  a 4000 X 4000 pixels minimum  on a video projection system on an imax dôme.
theire might be several solutions (i hope) but in term of filming formats what is the scale of quality :
is it
digit of 65mm in ?K  ?
35mm DMR process but i do not what to go back to a positiv
dalsa 4K
Viper 4K
if you had no problem with the budget but the best video image to project what would you choose?


A number of corrections here:

4000x4000 would be a 1:1 aspect ratio. There is no system that employs this.

There is no such thing as "4K HD." HD is, by definition, either 1280x720 or 1920x1080. If you are referring to digital imaging in general, I guess any pixel count or aspect ratio is acceptable.

The Viper is not a 4K camera. It is an HD camera, 1920x1080.

Presupposing "no problem with the budget" is somewhat foolish. All of the things you are alluding to are either brand new, experimental, non-existent, completely impractical, or absurdly expensive. Not necessarily in that order. Is this entire thread based on theory, just for information's sake, or is it based on some sort of reality?
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#11 Filip Plesha

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Posted 28 June 2005 - 07:48 PM

A 65mm 15-perf negative will give the best quality (Format size DOES matter).  65mm 8-perf is also a viable producton format.  Even 35mm full frame Super-35 can yield an excellent large format image, especially with digital processing like IMAX DMR.  8-perf 35mm VISTAVISION is also an alternative that would offer a grain advantage over 4-perf 35mm.

<{POST_SNAPBACK}>



Is 8-perf 65mm used for anything these days?
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#12 John Pytlak RIP

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Posted 28 June 2005 - 10:34 PM

Is 8-perf 65mm used for anything these days?

<{POST_SNAPBACK}>


Several sources of cameras and services, and producers:

http://www.hydroflex...werks8perf.html

http://www.mandy.com...s3.cfm?id=24776

http://www.williamsd...m/InCamera.html

http://www.paradisef...v_LgFormat.html

http://www.theasc.co...journey/pg1.htm

http://www.digitalpr...le.jsp?id=28121 ("Mystic India")

http://www.rpgproduc.../conforming.htm
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#13 Delorme Jean-Marie

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Posted 29 June 2005 - 12:54 AM

thank you all it was verry clear
the projecting system i'm using is the new Evans and sutherland digistar 3 planetarium projector.
It make a video image cut in 6 files, and projected by 6 hd projectors on an tilted dome up to 70ft wide.
the computer program make the picture back with no noticable edges between the 6 images.
the film is a signature film so all the budget goes in the image.


it's only thinking in a foolish way you can keep awake
;)
thank you again
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#14 David Cox

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Posted 29 June 2005 - 05:55 AM

Aha! Yes - I was going to add in my last post that the way to digitally project very hi-res images is to bank together multiple HD projectors, running from syncronised playback. We have post-produced a number of projects using this technique. Our biggest so far was 10 HD projectors side by side, for which we used a resoluton of 18K x 1080 (the screen was very long, with overlaps between projectors.) However, this was largely made of stills and graphics, so the problem of shooting a single image with the resolution to survive the big screen didn't arise.

So I would suggest the following. Shoot 65mm and have it scanned to a decent resolution. As I mentioned before, somewhere around 5.6k should do it. Then have these files copied to standard definition for you to do your edit. Once the edit is complete, you'll need to do a high resolution digital conform and grade, and add titles and effects as required. This will create a single hi-res master film. Don't even try and make 6 different films at this stage that all match up. Make one master film and split it up at the end. The delivery is then 6x HD streams, syncronised so that the projectors create a single image.

This is a very specialised post production job. Actually, not many systems can truely handle this sort of thing. Specifically, the problems are the very high resolution taking (in some cases literally) weeks to render, but more of a problem is getting the split out at the end. Most systems can't take one resolution as an input, and deliver a mathematically aligned section of it at a different resolution to the output. Other systems can do it, but in a very awkward way. For example, an inferno would require different disk partitions to handle the master resolution and the output resolution, making it diifficult to seamlessly work between the two. In the past we have used Jaleo for this sort of work, and this product has been replaced by Mistika. It is very able to do this sort of stuff, because it can mix resolutions very easily, allowing you to make one film that you split at the end.

But anyway - thats how its done!

By all means contact me if you would like more info about these multiscreen processes.

David Cox
Baraka Post Production Ltd
www.baraka.co.uk
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#15 David Cox

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Posted 29 June 2005 - 06:07 AM

A little more info, having looked into that projector.

The laser version of the projector claims a total pixel count of 16 million pixels. Without looking at the tech papers, my guess would be that this is the total of the 6 projectors added together. If this is the case, then it is likely that an area of 25% of each projector's range will overlap with the next projector. SO my guess would be that there are 12 million visible pixels (75% of 16 million) on the screen. Rough maths would give you a pixel resolution of 4000 x 3000 for that sort of thing.

If that is true, then scanning 65mm at 4000 x 3000 and making a master of that size would be the way to go. However, you'll need to get that real resolution from the projector manufacturer to be sure - I have just made some educated guesses here.

David Cox
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#16 Delorme Jean-Marie

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Posted 29 June 2005 - 01:16 PM

here we are pushing in the right direction, i wasn't clear enouth at the begining of my post.(sorry)
i have a new problem if i film in 65 it's the crappy lens..... and for this point i have no clue
i was thinking about the 10/70 japanese format, but i have no idea of this specific industrie, camera, lens..
is anyone aware????
thanks a lot david i'll try to keep you informed as soon as the project go on
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#17 David Cox

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Posted 29 June 2005 - 04:28 PM

If the final resolution is 4k x 3k, then you might want to test super 35mm on a fine grain stock. Do you know how big the final screen is? The difference between super 35 and 65 is of course definition and grain size. But I'm thinking that unless your screen is VERY big, super 35 might be good enough and then your not stuck with the awkwardness of shooting and scanning 65.

Perhaps the projector manufacturer could help you with this - maybe they have some projects shot on 65mm and some on 35mm that you could view?
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#18 Delorme Jean-Marie

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Posted 30 June 2005 - 12:10 AM

the screen has a diameter of 70 fet that's the size of an imax dome.(omnimax)
the manifacturer's industry is video projection for boeing, airbus and army simulators and planetarium so it as not experience at all with film or video.it's back ground is CGI and GI's .
I'd love to discover super 35 is a fine enougth format so i could use 35 lens (i'm verry atach to) , and cameras and stocks. (not all available in 65 , john ?)
so to you ,so far 35 resolution is still over HD (viper, c-mos, Dalsa) when it comes to project in video?
maybe a solution like vistavision, but i have to chek the formats size not to loose to much in the ratio.
definatly i'll have to go thrue test (i'm happy with that) but only yhe ones that make sens..
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#19 David Cox

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Posted 30 June 2005 - 03:48 AM

Yes, I think your answer lies somewhere between super 35mm and 15 perf 65mm. Obviously super 35mm would be the most convenient and efficient. However, the definition and grain size *might* be pushed at that screen size (which of course is viewed very closely by the audience).

But it's definitely worth a test, because the jump from super 35 to 65 means a lot more expense and awkwardness. So it has to be justified with a big jump in quality - which to a certain extent is down to the projector.

My guess is that HD would struggle with those parameters.
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