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November 17th, 2006, 11:03 AM | #31 | |
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November 17th, 2006, 02:15 PM | #32 | |
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November 18th, 2006, 06:34 AM | #33 |
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Hhmmm, with the shutter speed the same as the time interval for recorded frames you normally don't get those natural results. Of course, at 50p it might be difficult to see. (just try 25p at shutter 25... you'll know, i'm talking about the 180° shutter look)
Anyhow, unless it is staged you never know beforehand what piece of footage you'll be slowing down. The interesting part just consists of the fact you CAN slow everything down smoothly if you want. If I wouldn't be slowing it down anyway, I'd be shooting in 25p - which looks a lot more filmic, and you have to respect the cinematic rules in order to keep it looking good. Everything I'd shoot would be on 50p with shutter 100 then - but you are right, it would look as a HD100 with shutter 100 then...
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November 18th, 2006, 10:57 AM | #34 |
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50p is no different then 50i where 50i would use a shutter speed of 50. With 50i you have 50 interlaced fields. The only difference between interlaced and progressive is that with progressive each moment in time is the full resolution of the frame and not half the resolution. a shutter speed of 50 is the normal value of shutter speed regardless if you were shooting 12, 25, 50 or 100 fps.
Now if you prefer to shoot a shutter speed of 100 thats your choice but the HD200/HD250 is in no way worse in low light because you choose to shoot with a shutter speed of 100. In the case of 25p or 50p they represent the same moments in time it is just that the 50p has more images to represent that moment in time. Remember an interlaced camera will usually shoot with a shutter speed of 50 or 60 depending on if it is PAL or NTSC. Those interlaced frames show us the same moments in time as a 50p or 60p video. So in order to have a natural 50 hertz looking video just like the motion you would get with interlaced cameras you will use a shutter speed of 50. With 25p you would still use a shutter of 50 because the shutter represents that type of time interval. If you use a shutter speed of 25 with 25p you get a fake amount of motion blur because a shutter speed of 25 is not natural. By shooting 25p you are shooting at half the framerate but those frames still need to represent the same moments of natural time. You also have to remember that with 24p and 25p the 180 degree rule may apply but with 50p and 60p it is no longer film motion but video motion so the 180 degree rule doesn't really apply anymore. The extra frames help reduce the jitter and make everythign look natural. |
November 19th, 2006, 06:53 AM | #35 | ||
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I cannot see the point of shooting 50p with a 50 shutter-speed. definition won't go up (because the shutter speed is the same), slowing down isn't interesting because it'll look blurry and unnatural anyway (because the shuttertime is as long as the framerate-interval). The only thing is that you'll be able to pan at any speed you want, instead of respecting the filmic rules to keep it looking good... but your final result will look less crafted then anyway. For non-slowed-down clips 25p is fine (imo), you just have to craft your shooting skills. 50p definately opens up new possibilities, but only at shutterspeeds of 100 and up... Quote:
Furthermore, suppose you shoot 100 fps at a shutter speed of 50 (which you say is a normal value), what would be the point of shooting 100fps then? 2 following frames would be exactly the same because they are recorded in the same time interval - it would be virtually like shooting 50p. Try to shoot 25p with a 12.5 shutter speed - you'll know what I mean. Obviously a shutter speed of 50 would be fast enough not to notice when shooting e.g. 100 fps, but it would serve no point of recording 100 frames then.
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November 19th, 2006, 03:08 PM | #36 | |||||
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November 19th, 2006, 03:48 PM | #37 | |
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I think super motion cameras are possibly more the standard, shooting at 180 frames a second (NTSC) at high shutter speeds. These cameras also send out a regular video feed, etc. etc.: http://www.evs.tv/Products/SuperMotionMode.asp |
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November 19th, 2006, 06:52 PM | #38 | ||
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The other big issue with supermo is that the camera taken live on the air looks very juddery and the picture quality does not match the other cameras in the show. It's enough of a downside that you'll generally only see it used in shows that can afford to hire enough crew where you can have a guy running a camera that will only show up in replays. The one exception I've seen was the recent NBC Stanley Cup coverage where they used supermo on the high-tight shot, which for hockey is taken live very often. The quality difference between the high tight and all the other cameras was blatantly obvious. |
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November 19th, 2006, 07:10 PM | #39 |
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I'm sure you are right. There's just something that I can't understand about it. I don't understand how they make frozen images of fast moving people and objects that are completely sharp but are exposed for 1/60 of a second.
But then I also don't see how they keep everything in focus with the distances changing so fast from far to close... I guess just experience and turning the focus control based on the distance of the object from the lens. Then there are the flying cameras that are also in focus. Are they just very wide angle and using a fixed focus? |
November 19th, 2006, 07:45 PM | #40 |
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..........
Last edited by Jack Walker; November 19th, 2006 at 08:16 PM. |
November 19th, 2006, 09:06 PM | #41 | |||
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November 19th, 2006, 10:29 PM | #42 |
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I made some examples of how shutter speed affects motion rendering, including a hypothetical example of what an effective 720 degree shutter would look like and I have uploaded them here. In practice, you can achieve this effect by taking each frame and averaging it with the frame directly after, but ONLY with 1/50 or 1/60 shutter in 50 and 60p modes. You might end up with a slight "gap" in the motion trail, I haven't actually tried it.
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November 20th, 2006, 01:52 AM | #43 | |||||
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I watch F1 all the time, and those super slo-mo shots of the tyres in the chicanes definately are made with a higher shutter then the frame rate. Don't know what the frame rate is, but it could be as high as 400. By the way. a high shutter speed is just the thing for sports. Otherwise you'd lose the sharpness due to motion.
In sports, shutter speeds are dictated by the action rather then by the filmic result.... Quote:
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November 20th, 2006, 02:01 AM | #44 | ||
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November 20th, 2006, 02:04 AM | #45 | |
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