Film-Tech Forum ARCHIVE: IMAX DMR stuff: focus fluctuates

This is topic IMAX DMR stuff: focus fluctuates - Why? in forum Large Format Forum at Film-Tech Forum ARCHIVE.

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Posted by Mark J. Marshall (Member # 1409) on 11-28-2005, 04:04 PM:

I'm starting to wonder about a phenomenon that I've noticed with all of the DMR stuff that I've seen. From Apollo 13, Episode II, Batman, and now Harry Potter GOF, some shots are "sharp as a tack" and others are "kinda fuzzy." Why is this? Are these generally scenes that are filmed every so slightly out of focus and you just can't tell when you see it in 35mm? Or is there something in the DMR process that causes some images to be a little fuzzy. I usually notice this on close up shots, so it's not a "motion blur" thing. Any thoughts?

Posted by Brian Michael Weidemann (Member # 2243) on 11-28-2005, 08:47 PM:

The only fuzziness I ever notice is a very fine grain, which just looks like digital noise, in stationary objects, or backgrounds. It appears always to be there, but certain images just make it much easier to see them. I attribute that to nothing more than the original film grain trying to be sharpened up. Sharp whites or blacks get amazingly crisp, though.

The only IMAX "DMR" which doesn't have this grain is Polar Express, or at least I haven't noticed it. The colors are vivid and crisp, and there are no fuzzy or grainy bits to be found.

Posted by Mike Olpin (Member # 1115) on 11-29-2005, 02:40 AM:

I don't think Polar Express is DMR anyway, is it?

Posted by Brian Michael Weidemann (Member # 2243) on 11-29-2005, 06:49 AM:

I'm under the impression that Polar Express was entirely re-rendered and not remastered from its 35mm film version (which is what I attribute to the lack of grain and digital noise), yet the credits to the movie boast "IMAX DMR", so I guess the process applies. Also, it's included on DMR lists, so let's run with it. [Wink]

Posted by Mark J. Marshall (Member # 1409) on 11-29-2005, 08:52 AM:

Eh... Maybe I'm seeing things. [Cool]

Posted by John Pytlak (Member # 331) on 11-29-2005, 09:31 AM:

Certainly viewing a very large image at the relatively close seating distances found in IMAX theatres will show any deficiencies in the original image quality, such as errors in focus-pulling or excess graininess from underexposure. These issues would likely "fluctuate" from scene-to-scene.

Posted by Christian Appelt (Member # 1067) on 11-30-2005, 02:48 PM:

No matter how the image is "uprezzed" and scanned at high resolution, there is a limit to what can be done with 35mm. 65mm 5-perf origination would be the proper solution, for high quality 35mm release prints as well as for IMAX releases.

Recently I had the pleasure to see 20th Century Fox' new 70mm print of THE AGONY AND THE ECSTASY (1965), and with modern Eastman negative stock, 5-perf would look even better today.
I never saw the almost 3D-like effect of classic Todd-AO films in new movies.

Posted by Frank Angel (Member # 248) on 11-30-2005, 03:33 PM:

Even the print-downs to 35mm from those 65mm negs just looked sooo spectacular. I never saw the 70mm AGONY AND ECSTASY (it's one of my favorite great roadshow films -- it had a featurette attached to R1 about the Cistine Chapel that had cues for curtains and lights going into the feature), but I did run it as a roadshow 35mm 4trk mag print, and in those days the first run flagship houses got those awesome EK Show Prints, practically right off the 0-neg -- film never looked so good.

Imagine what film could look like as Christian says, if it's shot on 65mm modern neg emulsions and printed down to 35mm EK release prints using today's Kodak Vision emulsion! Add correctly applied Film-guard and the video evangelists would be scrambling to get everyone to re-invest in 8K projectors just to keep up. And all those poor suckers who invested $150,000 in 2K video projectors would be feeling like the guys on Wall Street in 1929....hehe.

Posted by Mark J. Marshall (Member # 1409) on 11-30-2005, 03:59 PM:

The New World is being partially shot in 65mm. I wonder how this would look as an IMAX feature.

IMDB Trivia Link

quote:
Although it was ultimately determined to be fiscally unfeasible to shoot the entire film on 65mm film stock, this has the distinction of being the first feature film in nine years to shoot on 65mm stock for non-visual effects shots. The last film to shoot in 65mm was Kenneth Branagh's Hamlet (1996), which remains (as of 2005) the last feature to be entirely shot on 65mm.

Posted by Stewart Anderson (Member # 1809) on 12-01-2005, 10:07 PM:

Hey John, I don't know much about the printing or re mastering process but can the IMAX DMR process compensate for and correct problems such as graininess (to a certain degree) and under/over exposure? It doesn't seem possible to compensate for focus from the original 35mm to 1570, but the other stuff, it seems like it wouldn't be too hard to correct via the DMR software.

Posted by Dan Suomi (Member # 2585) on 12-02-2005, 08:24 AM:

When some of us went to IMAX for projectionist training a few years ago, one of the guys in the camera department said that an IMAX camera was used to film parts of "Hulk".

Posted by John Pytlak (Member # 331) on 12-02-2005, 02:30 PM:

quote: Dan Suomi
When some of us went to IMAX for projectionist training a few years ago, one of the guys in the camera department said that an IMAX camera was used to film parts of "Hulk".

Maybe for background plates for the VFX?

Posted by Michel Hafner (Member # 3492) on 12-04-2005, 06:16 AM:

All IMAX DMR from 35mm I have seen so far showed digital grain reduction artifacts. The visibility depends on the objects/textures and the motion. It's usually well visible on human skin. The grain reduction is based on temporal filtering which is based on motion estimation. Motion estimation is often not 100% accurate. When there are no clear features to track from frame to frame or the object is not rigid some errors are pretty unavoidable. Human skin is especially difficult to get right. Such artifacts are also common on other digital intermediate jobs where grain reduction is applied. Whole films have been screwed up this way (The Aviator, Mr. and Mrs. Smith, Seabiscuit...).

Posted by Dan Suomi (Member # 2585) on 12-08-2005, 03:22 PM:

I think so John.