I thought I would post this, since it may be interesting to film / movie buffs here on this forum. I did a bunch of research a couple of years ago regarding film vs. digital resolution, and to determine what the actual resolution of 35mm film is. As many here probably know, 35mm film is theoretically a very high resolution medium. And, if you look at 35mm film frame by frame, that is actually the case. But when you project that same film - even with a very stable film projector - a large percentage of the actual resolution goes right out the window. Why? Projector film gate judder. This goes right to the point I made above about how capturing 4K levels of detail requires a locked down camera.
A rather large international study was undertaken a few years ago to test the actual resolution of film as compared to digital, by seeing how well film under ideal circumstances resolved detail using a specially created resolution pattern. The results were that an actual answer print had an effective resolution of about 1400 lines, with the release print having about 1000 lines. However, when the films were actually projected in state of the art commercial cinemas chosen by the test group, the visible resolution on screen dropped to an average of around 750 lines, the very best being around 875 lines. The main reason the resolution dropped so drastically was due to film judder in the projector gate. And this was using the very best projectors available using ideally prepared prints. So, DCI and Blu-ray have the capability of looking better than even the very best theatrical presentation of 35mm.
Here is a link to the study itself: http://www.cst.fr/IMG/pdf/35mm_resolution_english.pdf
Another test was to compare 70mm to 4K digital hosted by the Digital Cinema Society, with a theater full of cinematographers. This is from a report written by Howard Hall, a guy who shot lots of IMAX and 70mm undersea footage. The conclusion from the shootout? "When the audience was asked which image they liked best, the overwhelming response was that they preferred the digital projection. As an IMAX 70mm veteran, I found that quite astounding." Here is his report, if you care to read it for more technical details:
The “shootout” between 70mm and 4K was most interesting. We saw two clips projected via split screen then we saw the clips projected alternately. The first 70mm clip from “Pulse” was printed in the traditional way via negative, interpositive, and duplicate negative. The second 70mm clip (from Wild Ocean) was made in the more modern way via 11K scan from negative, then a 4K down-conversion, then film-out to 70mm. The digital projections were made via 11K scan and then 4K down-conversion. The 4K file of Wild Ocean was the file used for the film-out.
Just comparing the two 70mm clips was enlightening. The “Pulse” clip was significantly better than the film-out version of Wild Ocean. Scanning and film-out of Wild Ocean had been necessary because so many different formats in addition to 70mm were used in original image capture (we saw only 70mm original capture examples). Andrew Orin from FotoKem who made the film prints, estimated that even the “Pulse” clip had degraded to between 5.5 and 6K via the printing process (assuming original camera negative is about 11K).
In my opinion the split screen comparison showed that 4K projection is equal to or better than 70mm projection in all respects save one. The digital images appeared as sharp or sharper, they appeared to have more contrast in addition to equal or better resolution, and the color saturation and fidelity was equal or better. These differences were minor and debatable when the two “Pulse” clips were compared. The differences were dramatic when Wild Ocean was up.
The only remaining advantage to the 70mm projection was that the 4K projection was 16x9 and did not fill the vertical axis of the screen. That the bottom of the 4K screen image was missing was of no consequence to me since audience heads occlude the 70mm image at the bottom and to me this may be viewed as a distraction. The top of the screen is another story however. Some of the experiential effect is lost with the 4K projection though I confess I did not miss it much. This was the only disadvantage to 4K digital capture and projection that I could see and was but one point when scored against the myriad disadvantages, both financial and logistical, of shooting and projection in 70mm.
When the audience was asked which image they liked best, the overwhelming response was that they preferred the digital projection. As an IMAX 70mm veteran, I found that quite astounding.