Film-Tech Forum ARCHIVE: 48fps 3D and triple flash

This is topic 48fps 3D and triple flash in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Peter Castle (Member # 1997) on 01-04-2012, 10:15 PM:

Has anyone an idea as to how 48fps 3D will work with one projector?
It cannot be triple flashed. Double flashed would need 192fps total frame rate.

Also can shutter glasses handle it?

Posted by Victor Liorentas (Member # 5272) on 01-04-2012, 10:57 PM:

I don't think triple flash is needed at 48fps but not sure.

Posted by Monte L Fullmer (Member # 2797) on 01-05-2012, 01:03 AM:

it's a sync issue

Triple flash 3D only use 24fps to get out the 144fps for the "Z" and "XL" polarizer units to be in sync with the image.

More to gander on this

.pdf file on the topic.

What's a bit interesting is you have the polarizer in front of the lens on a 2d movie and just hold the glasses in front of your vision and not put them on. You can see each eye pulsate at 24fps between the two eyes opposite of each other in the lenses of the glasses.

Posted by Steve Guttag (Member # 268) on 01-05-2012, 02:38 AM:

As I understand it, it will be double-flash.

Starting with ICP 3.2.x, DLP projectors will be able to handle HFR stuff. Series 1 projectors will never be able to handle HFR and 3D, it was never in their spec and it would require expensive changes to get them to handle it. However, 48fps 2D IS within the capability of all servers and projectors as that was in DCI spec since day-1 or there abouts.

-Steve

Posted by Carsten Kurz (Member # 5396) on 01-15-2012, 06:39 AM:

Double-Flash at either 192fps (48fps) or 240fps (60fps). It seems that the 240 flips-per-second is no problem for series 2. However, blank-times/ghosting and light loss will have to be reconsidered for most 3D Systems at these higher rates.

http://www.christiedigital.co.uk/supportdocs/anonymous/christie-high-frame-rate-technology-overview.pdf

- Carsten

Posted by Frank Angel (Member # 248) on 01-15-2012, 11:24 AM:

Light loss? Yah -- that should improve the state of 3D. What are we going to readjust THAT spec down to...2ftL? Trying to make 48fps and 60fps work before laser light sources becomes wide-spread is folly. But then, don't go by me....I am convinced that doing 3D without dual projectors is folly to begin with, given the embarrassing light loss it asks audiences to accept.

And I have given up on all the geniuses who write these so-called specs. They start off saying, "OK everyone, you need 16FtL on a screen to make it look decent (we know if you can get more, it looks better, but OK, 16ftL is the goal). That's been the accepted spec for decades. Then comes along digital 3D and everyone is having multiple orgasms over it, but gee....they can't get 16, or 12 or 10ftL out of even the best digital systems; if they are lucky they can get 5. But they want digital 3D sooo badly that technicians, scientists actually say, "OK boys, here's how we fix it -- NEW SPEC. Get 3-5ftL and we'll say you're good." And I say, go screw yourselves. It's bullshit.

What is puzzling to me is that techs who usually are obsessive about getting everything exactly to spec, be it frequency response and sound pressure in sound, or any other spec, seem to be perfectly OK with this downgrade. It would be as if you went into a theatre to do a B chain calibration and the system couldn't get to 85db; would you recalibrate your RTA so it READ 85db with whatever the system could muster? I don't think so; or would you go back and tell the owner to get more amps and double your subbass speaker compliment? What we are doing with the screen illumination spec is going back to the owner and telling him that 72db is the new sound spec! THAT is what I feel has been done with the 3D screen illumination spec. You measure light off the 3D screen thru the polaroid glasses and it's nowhere near 16ftL or even the Drive in 12ftL spec, so what do we do? Do we tell the owner 1) get a bigger light source or use TWO projectors OR do we tell him 2) you can't get 16ftL but not to worry...the new spec is 5. The industry is doing the latter.

3 to 5ft looks like crap and everyone knows it. It's the cinema industry's version of the emperor walking around with no cloths. But hey, no one is about to say we can't do 3D yet because it can't meet any reasonable spec....we'll just change the spec. Someone tell me how it's not CHEATING. Someone tell me how talking about 48 and 60 frame rate is not folly without also talking about how to get more light on the screen.

Posted by Steve Guttag (Member # 268) on 01-15-2012, 03:31 PM:

Frank, which "tech" was saying that 3-5fL is good? That IS what the movies are timed for, at the moment...well 4.5fL +/- 1fL actually (XBRIGHT at 6fL being an exception).

You are also confusing film 16fL with digital 14fL...Now before you go getting your panties in a wad over the 2fL...remember, with film that 16fL OPEN GATE...no film. Shoot some film of the sun, process it, print it and then run it...now measure the light on that 16fL film projector...guess what...it will be 14fL or somewhat less (some claim processed film will drop it down to 12fL. This also applies to the crappy 3D digital spec...when comparing it to a "film" spec...all of the losses are built into the film spec.

I don't think anyone in the technical world is cheering low-light 3D...it is the reality we are currently dealing with. Heck, I'd be happy enough if 3D just went away, period! So much is thrown away in the name of 3D...not just light but light uniformity. Color saturation and uniformity also often takes a hit.

-Steve