Why can you see a differance in film and video tape? - Page 1
Forum section: electronics / general

author: Beamin
author_rank: Super Contributor
timestamp: May 29, 2019, 11:26:34 am
content: Ever since I was a kid and watched Dr Who, 1980's big afro dr who, you could tell the indoor shots were on video tape and the outdoor shots on film. The motion was different, and the still picture too; "crisper" for video, and "softer" for film. But what makes it do this if the frame rates are the same? I have also noticed that some youtube videos shot at 60 fps look like video tape when something moves quickly but other wise look like film. I take something more seriously when it looks like film, like the movies. Another interesting effect is watching sports films, if you watch "NFL's greatest upsets" When they were live on TV originally it looked like video tape but when produced into the movie it no longer looked like "video". This film/tape/video/show came out in the 1990's so was it recorded on video tape then strung together on film? Why would you do that? Anyone else notice this? I describe this to some people and they can't tell, but it's obvious. What makes digital cameras look one way or the other? Somethings look in between or even both.

author: tszaboo
author_rank: Super Contributor
timestamp: May 29, 2019, 11:32:42 am
content: Film is much higher resolution than video tape. For a 35mm film it is on par with 4K digital recording. Additionally, the time for open aperture is different. So motion is captured on the film, because it takes a longer time with open aperture. But of course the camera is larger, so they couldn't fit into actual locations.That is why they build sets in studios, where half the wall is missing, so the camera can fit. Dr Who would need so many sets that would never fit into budget.

author: Gyro
author_rank: Super Contributor
timestamp: May 29, 2019, 11:41:48 am
content: Whereas the video would have been recorded at 625 line back then.

author: wilfred
author_rank: Super Contributor
timestamp: May 29, 2019, 11:43:29 am
content: Dr Who wouldn't have been filmed on 35mm. 16mm is my guess and possibly in overcast days most of the time. The Dr Who of the 80's didn't have many sets that I remember. I don't think it was big budget. The studio lights would probably have been very powerful and maybe allowed a faster shutter speed. I remember a drama of the early days creating Dr Who with Jessica Raine as Verity Lambert, and one thing I remember was they were on a deadline for each shot in the studio because the lights were so hot they would set the sprinklers off. If the lights 20 years latter were still as big, hot and bright then they were pretty strong.

author: dmills
author_rank: Super Contributor
timestamp: May 29, 2019, 11:47:45 am
content: Also the gamma curves were very different and video would have been interlaced (so 50 fields per second) where film is clearly non interlaced (24FPS probably played out at 25FPS).I suspect Dr Who would have been shot on 16mm as well rather then 35, which makes one hell of a difference to the frame area, and no it probably was not 'super 16'), but then the video would have been 625i so not exactly HD either.1980s video cameras would have been tube based sensors (Probably videcon), and these needed (in the broadcast versions) significantly more support equipment then a simple film camera, so would mostly have been studio based.Budget telly (And it really was), you use whatever is available....

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: May 29, 2019, 12:02:13 pm
content: Don't know about Doctor Who, but another thing that can look off is that (high-end) film was often recorded with anamorphic lenses, which makes the image look different (the way the out-of-focus area renders is the main difference).It is very hard o say that 35mm = 4k. It depends a lot on the quality and lighting too. High-iso film might have grains larger than a pixel for 4k, so you can't really say it is 4K. Low-iso film might be higher. Another thing is that in general, when film is saturated, it is a more gradual roll-off: it somewhat compresses the highlights by itself. Modern digital sensors clip much harder, and some people say this is 'noticable' (however, I think most cinema-quality digital cameras have more dynamic range so that look could be approximated in studio? But I am not an expert and prefer not to get into that discussion.)

author: Beamin
author_rank: Super Contributor
timestamp: May 29, 2019, 01:13:23 pm
content: 35 vs 16mm and dr who aside, what else contributes? I can see how the amount of time the shutter was open when each frame would make the image look softer, the subject would be slightly blurry since things move a tiny amount during the time the shutter was open. Why would you see digital look one way or another? Maybe this is one of those things people notice but never question, like how does string get tied in knots when it sits in a box and is never looped through itself, yet a knot requires unlooping.Would the scan lines catch more motion: when the bottom line is scanned the subject has moved slightly since the top and the bottom line reflects this, where as the film would be blurred consistently from top to bottom of frame. Do they make filters in editing software to make your video look one way or the other? I would like a VHS home movie filter, or big screen movie filter.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 29, 2019, 01:28:07 pm
content: In the U.S., film was shot at ~24FPS and "2:3 pulldown" converted to the 59.94 output fields per second, for the 29.97i system. In Europe, mostly, film was shot at 25FPS, and directly converted to the 50 output fields per second for the 25i system. Video always was 59.94 fields per second in U.S., and 50 fields per second in Europe. Hence, video images had smoother motion, simply due to the higher number of actual captured frames in time!Film, at 24FPS, would appear more "choppy" unless compensated with "adding" motion blur, by keeping the shutter open as long as possible between the frames. In addition, this classical frame rate requires some careful motion planning. Still, many movie experts think that thislowframe rate creates some "magic", and I tend to agree to some extent. So, many/most(?) modern films are still shot at 24FPS.Any arbitrary framerate could have been chosen at any point in history, so I guess the visual "magic" was always considered to be there. Nothing prevented the TV series producers who used film to shoot the film at the higher TV framerate, yet they usually didn't.Another thing, dynamic range.Video cameras - especially earliest CCD cameras - had horrible dynamic range. Large studio vidicon tube cameras were better in this regard, but still very high in contrast. You know how you take a picture with your camera/phone when the sun is shining, and the bright, light up areas end up washed out? It was 100x worse back then. Film was almost free of this problem, with its massive dynamic range.For indoor shots in studio, lighting can be controlled carefully to avoid combination of light and dark areas, so video was usable for production there.For outdoor work, video tended to look to have way too much contrast, with highlights blown out. Additionally, outdoor work with video required the usage of smaller, portable equipment which was even worse in image quality (see the relevant news footage from the same age to see what I mean).Video tape technology is relevant as well. It was not until late 1980's and Betacam to allow fairly high-quality storage in a small (< 10 kg) mobile device. Before that, high quality video tape recorders were heavy and large instruments; mobile recorders had poor quality.Film converts the high dynamic range of the input scene (say, D=4.0 or 13 stops) to a flat reproduction on the actual film (say, D=1.5 or 5 stops), which is just right for the telecine camera to "scan". In other words, a real-world scene with a lot of contrast ends up gray and flat on the negative (or special telecine copy print film), but when this flat film is shot again with a telecine camera for broadcasting, the contrast is bumped up again, and the end result is natural. Compare this to directly capturing the scene with a high-contrast camera.The massively poor dynamic range, which looks like excessive contrast, gives a "sharp" feeling to the video image. Film images tend to be flatter in contrast, appearing less sharp.16mm film equipment, on the other hand, was truly mobile, cheap and ubiquitous, and for a TV work, has more than necessary resolution and small enough grain, even given the 1970's film stocks. The resolution did exceed the TV spec, so no need to go for 35mm for just TV production, unless it was a really high-profile production.16mm film, later evolving into Super-16 with enlarged film gate to produce wide-screen material, has been widely used for high-profile TV series production much longer than people know, being the de facto high profile workflow still in the early 2010's, and to some extent, it's still being used. The increasing sharpness and decreasing grain size of the film stocks helped in this process; Super-16 had no issues at all to produce high-quality full-HD and 2K material using modern materials like Kodak Vision3, introduced around 2010 IIRC.Given the fact that single pixel (PMT tubes), and 1D CCD line imagers had decades of image quality headway compared to complete video/digital cameras, the film remained quite long as an intermediate "capture" format, even in otherwise fully digital workflow, just to be digitized right after processing. The film scanner can use much fewer pixels of much higher quality (just 1, or say, 4000 to scan line at a time in 4K), these pixels don't need to have more than about 6-7 stops of dynamic range to read the film with its compressed contrast, and it doesn't need to happen in real-time.Of course, a modern digital camera now has enough both dynamic range and resolution to challenge or even surpass film, but people are surprised to hear how long it took to reach this point. Film was still technically superior just a decade ago.(Disclosure: I ran a small-scale/experimental motion picture film processing and digitizing business.)

author: David Hess
author_rank: Super Contributor
timestamp: May 29, 2019, 01:40:32 pm
content: Quote from: Siwastaja on May 29, 2019, 01:28:07 pmThis is the reason for the marked difference in appearance of film and video on television in the US. I usually noticed it when viewing "soap operas" which were almost always shot on video and this became associated with cheap production.I do not know what the difference looked like with 50Hz PAL in Europe. I assume it was much less.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 29, 2019, 01:46:16 pm
content: Quote from: David Hess on May 29, 2019, 01:40:32 pmIt's basically the same I think, because human vision system doesn't resolve temporally much beyond about 40-50FPS (high-end gamers might disagree with me on this), so both 50FPS and 60FPS look about equally perfectly smooth. So I think the effect of 24FPS vs. 60FPS in the US, or 25FPS vs. 50FPS in the Europe, is very similar and we both mentally connect it to soap operas.OTOH, I think we have a large difference between US/Europe regarding the TV flicker. Here, the 50Hz CRT flicker was very noticeable, almost painfully so in peripheral vision. Which is why 100Hz CRT televisions were a really big thing in the late 1990's, as soon as digital processing to double and interpolate frames became feasible in low-cost mass-market.I remember how I first time accidentally fed NTSC to my PAL TV (through my video editing card - those were expensive as hell), and even though I didn't see any color, it did sync up and my first reaction was: WOW, it doesn't flicker!

author: nali
author_rank: Frequent Contributor
timestamp: May 29, 2019, 02:35:21 pm
content: Quote from: Siwastaja on May 29, 2019, 01:28:07 pmIt's normally fairly easy to spot film content either by the picture wander, or the black speckles (or white speckles if it's a negative film) of dust/hair/crap that appear. As someone who used to work on Telecines I notice that a lot, but that was 35+ years ago and I do find it surprising seeing on reruns from say the 90's or maybe even later.

author: David Hess
author_rank: Super Contributor
timestamp: May 29, 2019, 03:15:53 pm
content: Quote from: Siwastaja on May 29, 2019, 01:46:16 pmBut in the US, it was the 3:2 pull-down used to convert 24 FPS film to 60 Hz NTSC video which gave film its distinctive look on video.In Europe with 50 Hz PAL, the film could be run slightly faster or 2:2:2:2:2:2:2:2:2:2:2:3 pull-down used which I suspect would not be as apparent as 3:2 pull-down.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 29, 2019, 03:41:16 pm
content: Quote from: David Hess on May 29, 2019, 03:15:53 pmOh yes, I see what you mean, you have quite a bit of jitter there. It'll surely give a distinctive extra effect, on top of what we are already are seeing wrt. different frame rates, dynamic range, etc. Especially during pan/tilt scenes.In Europe, we had this distinctive effect of movies feeling a bit different in the theater vs. on television, since on TV, it was sped up by 4%, which is evident on music especially for people close to having "absolute pitch" skill.

author: tooki
author_rank: Super Contributor
timestamp: May 31, 2019, 11:19:40 pm
content: Quote from: Siwastaja on May 29, 2019, 01:28:07 pmThe slower shutter speed is what gives the “dreamy” film look, whereas video (with 50 or 60 fields per second) forced faster effective shutter speeds. (It’snotthe 3:2 pulldown that causes the “video look”, you get it on natively recorded video, too!!)Some later video cameras actually supported 24fps progressive frame acquisition, doing 3:2 pulldown to interlaced 29.97fps in-camera before writing to tape. This way you could get the 24fps look even on video.