Could you really get 18K equivalent of resolution from IMAX film ??

[Lucamancini]

For those who don’t know, IMAX film format is basically 5 perf 65mm motion picture format turned vertically and shot 15 perforations to give the dimensions 70.41mm x 52.63mm(3 times the area of 5 perf 65mm) which is almost the same size as 6x7 medium format film and uses Kodak Vision 3 film(50D, 250D and 500T)

Now, IMAX has been spouting 18K as the resolution(yes, I know film doesn’t have a fixed resolution) for their film since forever and I’m wondering how true this is ?? I’m sure hardly anyone here has shot on it because it’s a motion picture format but considering it is almost the size of 6x7 film, someone might have an idea.

 

[Paul Howell]

I might be wrong, but film does have a fixed resolution, the resolving power for Kodak black and film is listed on the data sheet, Tmax 100 is 200 LPM, what does effect the resolution is the lens, modern lens are capable of resolving Tmax 100. Not sure what Color film can resolve, as general rule is the slower the film the greater the resolution power. So if some of the film is shoot on the ISO 50 film and indoors on the 500T there will be a difference in resolving power. I have only seen a few IMAX films but I have not noticed a jump is clarity or detail or grain. Not sure of the math, but 18K seems to be conservative.

 

[L Gebhardt]

18K in this case would be spread over 70.41mm (using your numbers). That's 18432 pixels/70.41 or 262pixels per mm (6650 ppi). I don't have a film scanner that will go that high, but I have scanned film with a digital camera and macro lens at a higher resolution and the scans do appear to hold more detail than at lower resolutions, though I suspect much of that is better resolved grain clumps on most films. But I don't think it's an exaggeration to say an 18K scan will look better than a 12K scan for the slower imax films.

 

[Rudeofus]

No lens will offer this kind of resolution over the whole image frame. The lenses, which do outresolve TMX, will do this in the center of a 35mm frame.

And even if you find a lens, which offers this kind of resolution: In order to reach the 4µm resolution you need to have an aperture larger than F/3.5 in order to avoid diffraction limits, and with a maximum CoC diameter of 4µm you will have DoF as thin as a sliver. Do the math.

These theoretical resolution numbers are completely worthless, and this applies to both analog and digital media.

 

[mshchem]

Marketing

 

[Kilgallb]

Hmm.. I think Chris Nolan could afford a good lens.

 

[Rudeofus]

Hmm.. I think Chris Nolan could afford a good lens.

Nolan certainly didn't have to deal with cheap lenses, but even he could not beat the issue with diffraction limit and DoF.

 

[braxus]

Somehow if one shot 18K on a digicam, vs film, the digi would look sharper. Film has a softer look, even with larger formats. Its part of the appeal of film. But I'll stop there since this isn't a hybrid forum section.

 

[Rudeofus]

Somehow if one shot 18K on a digicam, vs film, the digi would look sharper. Film has a softer look, even with larger formats. Its part of the appeal of film. But I'll stop there since this isn't a hybrid forum section.

It's easier to sharpen a digital image, and that's most likely what happened in your tests.

 

[PinkPony]

My guess is no based on interpolating my own scanning results with DSLR and macro lens.
My estimate lands around 10K but there are many factors. Film used, motion blur etc.

 

[faberryman]

Would someone be kind enough to set forth the equation by which IMAX film is determined to achieve "18K resolution". Thanks.

 

[L Gebhardt]

Would someone be kind enough to set forth the equation by which IMAX film is determined to achieve "18K resolution". Thanks.

I think in the cinema world they mean 18 * 1024 pixels across the screen. https://noamkroll.com/the-definitiv...r-video-2k-4k-6k-8k-every-other-major-format/

 

[faberryman]

I think in the cinema world they mean 18 * 1024 pixels across the screen. https://noamkroll.com/the-definitiv...r-video-2k-4k-6k-8k-every-other-major-format/

Those resolution designations are all digital. It is not clear to me how you get from film resolution to digital resolution.

 

[L Gebhardt]

Those resolution designations are all digital. It is not clear to me how you get from film resolution to digital resolution.

My read on the claim is they are saying the IMAX film has enough resolution for an 18K digital projector. Presumably projecting an 18K scan shows more detail than a lower resolution scan. But as noted above film does not have a fixed resolution rating. Even resolved line pairs are given at a multiple to contrast ratios to account for this. Maybe Openheimer is just a series of white and black columns with some dialog. They might get to 18K that way.

 

[btaylor]

"IMAX film format is basically 5 perf 65mm motion picture format turned vertically and shot 15 perforations to give the dimensions 70.41mm x 52.63mm" nitpik here, the film travels horizontally, as standard motion picture film travels vertically. VistaVision was a similar orientation, although it was in 35mm.
I gotta say, a 6x7cm frame is huge- whatever the resolution measures, its massive!

 

[L Gebhardt]

"IMAX film format is basically 5 perf 65mm motion picture format turned vertically and shot 15 perforations to give the dimensions 70.41mm x 52.63mm" nitpik here, the film travels horizontally, as standard motion picture film travels vertically. VistaVision was a similar orientation, although it was in 35mm.
I gotta say, a 6x7cm frame is huge- whatever the resolution measures, its massive!

It really should be impressive. I think the nearest theater to me that will project the film is about a 4 hour drive, but it still might be worth it for the experience.

 

[faberryman]

My read on the claim is they are saying the IMAX film has enough resolution for an 18K digital projector. Presumably projecting an 18K scan shows more detail than a lower resolution scan. But as noted above film does not have a fixed resolution rating. Even resolved line pairs are given at a multiple to contrast ratios to account for this. Maybe Openheimer is just a series of white and black columns with some dialog. They might get to 18K that way.

Yeah, I was just looking for the calculation they used in arriving at 18K. Presumably they didn't just pull a number out of the air.

 

[Bronson Dugnutt]

All of the 21st century and many decades prior, much of society has been keenly focused on the miniaturization of just about everything except measured resolution. Medium format motion picture is an appropriate medium (no pun intended) for the subject matter in this case.

Did anyone manage to see the Apollo 11 documentary in an IMAX theater? Would it have been any better in 24K?

I blame the transistor for the dearth of 11x14 motion picture projectors available nowadays