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IMAX vs. IMAX 70mm: The difference between these two cinema formats

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Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#141

Post by IndySun »

keane wrote: post #120
tshaddox wrote: post #75

Earlier quoted context omitted.

Aspect ratio by itself tells you very little about the theatrical viewing experience. What really matters is the "angular image size," i.e. the horizontal and vertical angle that the image fills in your field of view. This is determined by the aspect ratio of the image, but also critically the size of the screen and the distance from the screen to the viewer. 1.43 IMAX screens are really really big and fill more of y…

Related: Chart Of Common Viewing Angles from Steve Yedlin, ASC https://www.yedlin.net/NerdyFilmTechStuff/#:~:text=Chart

I love the OLED entry there. Virtually what I do to all my friends' TV's when I visit.

Yes, it's an annoying thing to do, and they're all "hey, don't change my settings..." at first, but a few seconds later the TV looks better, clearer, brighter.

https://www.yedlin.net/NerdyFilmTechStuff/OLED_Settings

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#142

Post by SirMaster »

kridsdale1 wrote: post #125
SirMaster wrote: post #99

Earlier quoted context omitted.

I am not even sure why the theoretical resolution matters when they seem to have so much trouble pulling focus on the actors on an old film camera like the IMAX cameras they use to where the footage is fairly blurry in a lot of cases. If they used a 6.5K or 8K digital cinema camera they would get all the advanced autofocus abilities those camera have nowadays to keep the actors sharply focused and would end up with m…

Sensor size. Depth of field is optically different on large frame cell size or sensor size vs 35mm. That camera you reference is not optically equivalent.

Sure, but if you watch the Odyssey, you would see how the camera operators struggled to keep focus in some scenes. A modern digital cinema camera would have no trouble with it's advanced auto focus abilities. So the resolution of the film is kinda irrelevant because of that some of the time.

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#144

Post by ralferoo »

anon7000 wrote: post #64
ralferoo wrote: post #62

Earlier quoted context omitted.

> Now we're being told the opposite. The choice of unusual film standards has always been to make the film a bit "special" when viewed in a suitable cinema. The original format 1.33:1 was simply using 35mm wide film (originally 1.35") and after putting sprocket holes on each side, there was 1" of usable width, and someone decided to make a frame 1" x 0.75". The projected image was just scaled linearly. When they star…

I don’t think you covered the difference between 70mm and IMAX 70mm. One frame of IMAX is basically 3 frames of normal 70mm. So it is physically 3 times bigger I’d say that yes it’s a marketing technique, but for these releases it’s not a gimmick. If you have a chance to watch a film in 1.43:1, you should try it. The difference is how big it is, and especially how tall it is. Most theatres don’t physically have the s…

> ... the difference between 70mm and IMAX 70mm. One frame of IMAX is basically 3 frames of normal 70mm.

Oh, thanks for pointing that out. It's alluded to in the article, but I hadn't twigged that they'd increased the size of the frame. Yeah, that definitely means there's a lot of scope for just massively increasing the height of the screen whilst keeping it wide, and so it's definitely going to be an issue for a lot of cinemas to fit it in without just shrinking the image size substantially so the height fits, at which point the extra resolution would only make it look less grainy.

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#145

Post by ralferoo »

KaiserPro wrote: post #112
anon7000 wrote: post #64

Earlier quoted context omitted.

I don’t think you covered the difference between 70mm and IMAX 70mm. One frame of IMAX is basically 3 frames of normal 70mm. So it is physically 3 times bigger I’d say that yes it’s a marketing technique, but for these releases it’s not a gimmick. If you have a chance to watch a film in 1.43:1, you should try it. The difference is how big it is, and especially how tall it is. Most theatres don’t physically have the s…

> between 70mm and IMAX 70mm. Im not sure how many vertical 70mm projectors there are left. I don't think its a delivery format any more. In terms of shooting, I think the only person mad enough to use 65mm is Ken Branagh on his agatha christie movies. its easier and a fuckload cheaper to shoot anamorphic on 35mm or 35mm digital. Plus I think the choice of scanner is wider. Thats also another good point, I'm not sure…

Yeah, I haven't been involved in film projection since late 1998. Back then, it was at my university student cinema, we had 70mm capability but only showed one or two films a year in 70mm because there were so few films available for us to hire in that format. If I recall, the main one we showed every year was Backdraft. By comparison, there were 2 showings per day during term time (so 7x10x3 days per year) and most films would only be shown 1 or maybe 2 nights.

I was told then that we were very lucky to have that projector as there were only around 4 or 5 cinemas in the country with 70mm projectors (other than IMAX), and I can only imagine it's gone down since then. That said, it's hard to find information on it now - the only list of 70mm cinemas I could find had 5, but included IMAX and not my university cinema even though they showed Interstellar in 70mm last year so probably are just not listed because it's not open to the general public.

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#146

Post by mixmastamyk »

supermatt wrote: post #143

How does "shooting" on 70mm relate to the projection of the 70mm? I have absolutely no idea how any of this works, but are there no CGI effects in the movie or how does the CGI get on the film?

The article mentioned some optical/in-camera effects, and images can be scanned and printed on film as well.

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#147

Post by keane »

IndySun wrote: post #141
keane wrote: post #120

Earlier quoted context omitted.

Related: Chart Of Common Viewing Angles from Steve Yedlin, ASC https://www.yedlin.net/NerdyFilmTechStuff/#:~:text=Chart

I love the OLED entry there. Virtually what I do to all my friends' TV's when I visit. Yes, it's an annoying thing to do, and they're all "hey, don't change my settings..." at first, but a few seconds later the TV looks better, clearer, brighter. https://www.yedlin.net/NerdyFilmTechStuff/OLED_Settings

Guilty as well. Though I will sometimes check the rtings.com /settings tab from a similar model for a reminder of where various proprietary naming toggles are located in the menu (and then run the Apple TV iPhone-powered calibration if they have one). Network programming/soaps and Netflix originals still look terrible afterwards though.

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#148

Post by mixmastamyk »

gamblor956 wrote: post #93

In the LA area, both Regal and AMC have a number of IMAX 70mm theaters. Universal City AMC and Irvine Spectrum Regal both have the biggest IMAX screens. TCL in Hollywood has the next biggest. The downtown Regal and Burbank AMC are in the third tier (bit still very large). All of these theaters have IMAX 70mm film projectors.

Huh, I'd only seen IMAX at the California Science Center and it blew my mind at the time. But according to this article and site below, apparently haven't really seen IMAX:

- https://cinemadb.net/auditorium/2513 - CSC, says it is only 4k!

- https://cinemadb.net/auditorium/2511 - Hollywood Chinese

- https://cinemadb.net/auditorium/2512 - Regal LA Live

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#149

Post by dbspin »

e0 wrote: post #107
dbspin wrote: post #34

Earlier quoted context omitted.

Every film is colour corrected and graded digitally (in addition to all the special effects and compositing work), and this is in fact one of the cheapest parts of the process. So no, it's not remotely a consideration.

In his 60 Minutes profile, Nolan shows how The Odyssey was color corrected optically https://youtu.be/1GEqDZ3hQSo?si=8AP4TI9iY9otLrjM&t=271 I had the same question. I wondered why seeing a 70mm print was supposed to matter if it was going to get digitally edited and color graded anyhow. The answer turned out to be that neither of my speculations were true.

That's fascinating - presumably a facet of the IMAX process.

The majority of films shot analogue are graded digitally. Because the most popular film stock they use (Kodak Verita 200D, employed for it's 'classic' look, good skin tones and modern niceties like anti static and anti halation) requires a digital stage in development [1].

[1] https://www.kodak.com/content/pdfs/motion/KODAK-VERITA-200D-...

Re: IMAX vs. IMAX 70mm: The difference between these two cinema formats

#150

Post by dbspin »

chris_va wrote: post #52
dbspin wrote: post #33

Earlier quoted context omitted.

Some directors like the appearance of film... Given that the spectacle is a large part of the reason we go to the cinema, the colour fidelity and (and in the case of IMAX) unique scale and aspect ratio are the point... Not sure why practicality or cost would override that? As a director who doesn't shoot on film - I still see the appeal, there's a particular quality to skin tones - especially in response to older arc…

I know extensive thought goes into filters in front of the camera and the lighting, but one can probably change the bayer filter transmission function to get them to match better (and maybe add one or two channels at the cost of shot noise). I see this in industrial cameras, do you know if any filmmakers use non standard Bayer filters?

The only cinema cameras I know of that don't employ some variation of a bayer filter in the colour science are black magic cameras. Their higher end cameras all have an RGBW sensor with a 6*6 grid including a white photo site. This is way beyond my technical level of expertise to understand or explain, but there's some more info below.

https://www.cined.com/ursa-cine-12k-blackmagics-rgbw-sensor-...

Broadly speaking these cameras aren't used on any major features. The market is still pretty much exclusively Sony and Arri.

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