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Old 14th December 2009, 16:09   #31
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Dear IT
If you want smear, what is a better shutter speed: fast or slow?
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Old 14th December 2009, 16:27   #32
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You wrote:
(3) 150 FPS or higher recording has nothing to do with realism but when you record at high frame rate and play them at normal 24 FPS it provides better details example in fight scenes you can distinguish how the punch gets delivered on face and how jaw gets deformed and blood flows.

I’m not sure how this is achieved, but again this is not useful to the discussion.
Shooting at higher frame rates and then slowing it down while playback is a standard technique used in producing very smooth looking slow motions. How it produces such a neat and smooth slow motion is self explanatory if you think about it.

There is a program in Nat Geo or some similar channel where they shoot everyday life activities in very high fps and play it slowly with a lesser frames per second. Its is amazing to watch how things happen with a slowed down sense of time.
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Old 14th December 2009, 16:36   #33
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There is a program in Nat Geo or some similar channel where they shoot everyday life activities in very high fps and play it slowly with a lesser frames per second. Its is amazing to watch how things happen with a slowed down sense of time.
It's called Time Warp.
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Old 14th December 2009, 16:55   #34
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Shooting at higher frame rates and then slowing it down while playback is a standard technique used in producing very smooth looking slow motions. How it produces such a neat and smooth slow motion is self explanatory if you think about it.
Heh, heh... Here is some trivia from my side.

The technically and realistically most perfectly choreographed fight ever. Even after 4 decades, it has not been bettered. The final running kick broke the opponent's sternum and broke the hands of the two extras who caught him. That's how realistic it was. The opponent was Robert Wall, a real heavyweight world-champion in kick-boxing.



In this scene, Bruce Lee used to move so fast, they couldn't capture his moves. Finally they shot it 4 times faster, so that they can slow it down a little for the audience to appreciate it. Not just the slow-motion moves, even the normal looking scenes are slowed down. Or else you won't see anything by blurred hands and legs.

But they didn't bother doing it in Kurasawa movies like Yojimbo and Sanjuro. The final fight scene lasts less than 1 second in Sanjuro. I had to slow the DVD play to 10 times slower to make out the exact move in the last scene of Sunjuro.

Finally, I thought this was a DSLR thread, why are we talking video so much?

Last edited by Samurai : 14th December 2009 at 17:07.
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Old 14th December 2009, 17:08   #35
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Yes, this is the source of a confusion for many.

shutter open time
<-->

|XXX________|XXX________|XXX________|XXX________|X XX________|

<----------->
a frame
Ditto!


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Originally Posted by clevermax View Post
I have a different question, somewhat related to DLSRs: Most of the new DLSRs have HD video capturing capability as we know. I've heard that any DSLR's shutter has a line time (no. of actuations) So, does this mean that shooting HD videos for long will significantly reduce the lifetime of a DSLR?
Electronic Shutter is implemented in the firmware for video shooting. Even current arri digital has electronic shutter for videos.

During a video, shutter opens and then sensor gets exposed. Here electronic shutter comes in play and when one stops shooting video, shutter gets closed. It gets counted as 1 complete shutter actuation.


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Originally Posted by proton View Post
Dear IT
If you want smear, what is a better shutter speed: fast or slow?
Depends on a lot of factors but to keep the conversation simple. I would say generally slow shutter speed will give your smear.

We are taking about motion blur in videos here which is completely off-topic from motion blur in still photography


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Originally Posted by Proxima View Post
It's called Time Warp.
If you haven't seen chainsaw juggling in slow motion, one hasn't seen anything.



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Originally Posted by Samurai View Post
Finally, I thought
this was a DSLR thread, why are we talking video so much?
Because DSLR's are now infected with Video mode.

Off topic, How many users are interested high speed photography tools???

Cheers

Last edited by it_inspector : 14th December 2009 at 17:18.
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Old 14th December 2009, 17:42   #36
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Depends on a lot of factors but to keep the conversation simple. I would say generally slow shutter speed will give your smear.
Bingo! 24 fps give you 1/48 sec shutter speed, thereby giving the desired smeared (motion blur) look!
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Old 14th December 2009, 17:52   #37
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Originally Posted by proton View Post
Bingo! 24 fps give you 1/48 sec shutter speed, thereby giving the desired smeared (motion blur) look!
I am no expert but AFAIK, it is not necessary that in 24fps you will always have a fixed shutter speed. Then how do you shoot in varying light conditions? Please refer to the diagram which I drew using ascii text a couple of posts above.

Last edited by clevermax : 14th December 2009 at 17:53.
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Old 14th December 2009, 19:38   #38
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@ITInspector
Just a pointer, all the 24 fps digital video files I work with for Visual effects and CG compositing have much more motion blur than 30 fps or 60 fps. Plus, what is the point in playing back something caught at 60 fps, at 24 fps...thereby slowing it up. In case you drop frames...then why capture them at the first place.
Regards,
TG.
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Old 14th December 2009, 21:17   #39
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Originally Posted by Torqueguru View Post
@ITInspector
Just a pointer, all the 24 fps digital video files I work with for Visual effects and CG compositing have much more motion blur than 30 fps or 60 fps. Plus, what is the point in playing back something caught at 60 fps, at 24 fps...thereby slowing it up. In case you drop frames...then why capture them at the first place.
Regards,
TG.
Fast action shots or fast panning shot at 24p and played back at 24p causr severe jittering. It was not a big deal during film times as dual shutters corrected this in cinema halls (it works on film only and not with digital) and anything on a VCR/betamax was pulled down to pal/ntsc. There was no means for consumers to play this content at 24p with original resolution.

But now since we have means to SHOOT and PLAYBACK both at 24p and content can be delivered via bluray discs, it is causing quite a few headaches.

A consumer spend $800 on a bluray player, $2000-3000 on a high end Projector and $2000 on amp+speakers combo and suddenly in middle of a blockbuster there is so much jittering and after checking everything, the only possible way to play it is by pulling down 3:2 to 60i/60p.

If you have access to Projector/Plasma with native 1080p and bluray player which can playback at 24p, just rent Casino royale bluray and watch it at 1hr 11mins when camera pans across room, the whole picture gets screwed by jittering. Newer titles coming on bluray's are already edited and pulled to 60i/60p and then back to 24p during fast panning and fast action scenes, to avoid jittering.

Like i said i do not play with video much and will not do it till February next year. All the information i have is from talking to people in studio and at photography clubs and these are the people who shoot video day in day out for different clients.

Cheers
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Old 14th December 2009, 21:48   #40
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Originally Posted by it_inspector View Post
If you have access to Projector/Plasma with native 1080p and bluray player which can playback at 24p, just rent Casino royale bluray and watch it at 1hr 11mins when camera pans across room, the whole picture gets screwed by jittering. Newer titles coming on bluray's are already edited and pulled to 60i/60p and then back to 24p during fast panning and fast action scenes, to avoid jittering.
There is some unavoidable jitter with fast panning, even with a 24p capable TV/Projector:

Quote
I agree. If you watch a blu-ray on a tv that only supports 60fps then you will get what many call "judder" in a lot of fast motion or panning shots in the movie. It looks a little slideshow-ish. Having a 24p display smooths out motion by a good margin making things look much better. Keep in mind though all things shot in 24FPS film, etc. will have some choppyness in fast action as there aren't enough Frames per second to keep up with the fast motion.


What is the benefit of 24fps vs. 60fps? - Blu-ray Forum

Last edited by proton : 14th December 2009 at 21:49. Reason: tidied up
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Old 15th December 2009, 05:23   #41
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Originally Posted by proton View Post
There is some unavoidable jitter with fast panning, even with a 24p capable TV/Projector:

Quote
I agree. If you watch a blu-ray on a tv that only supports 60fps then you will get what many call "judder" in a lot of fast motion or panning shots in the movie. It looks a little slideshow-ish. Having a 24p display smooths out motion by a good margin making things look much better. Keep in mind though all things shot in 24FPS film, etc. will have some choppyness in fast action as there aren't enough Frames per second to keep up with the fast motion.


What is the benefit of 24fps vs. 60fps? - Blu-ray Forum
Would you mind reading the next comment please???

It will tell you how jittering/juddering is removed in a Cinema hall using double shutter.

And 80% of the comments there, well users are confused between hz and fps themselves, i cannot expect them to even understand 24p format let alone compare it with 60i/60p.

Why will cine projectors have correction for 24fps if it 24fps had SMOOTH motion ???

I have said it so many times and i am almost ready to give up. A video is not worth SHOOTING at 24fps, it is always better to SHOOT at higher fps and then down SAMPLE it to play at 24p.

Cheers
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Old 15th December 2009, 13:19   #42
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Originally Posted by it_inspector View Post
Would you mind reading the next comment please???

It will tell you how jittering/juddering is removed in a Cinema hall using double shutter.

And 80% of the comments there, well users are confused between hz and fps themselves, i cannot expect them to even understand 24p format let alone compare it with 60i/60p.

Why will cine projectors have correction for 24fps if it 24fps had SMOOTH motion ???

I have said it so many times and i am almost ready to give up. A video is not worth SHOOTING at 24fps, it is always better to SHOOT at higher fps and then down SAMPLE it to play at 24p.

Cheers
Patience, boss.

Now we have solved the problem of “soft focus” (a desirable property), lets move to flicker reduction.

Now, double shuttering was used to reduce FLICKER! 24 fps used to give an interval between successive frames, causing the eye to be exposed to no-light and bright –light states. Double shutter projection held the required frame for 2 projections (time interval) at aperture gate in combination with the shutter leaf. Remember, two complete images MUST be projected. Sliding the images past the arc light will only give blur. Two sequences of positioning the frame at the aperture gate synched with 2 FLASHES of light from the shutter/arc light mechanism will deliver the required 2 projections.

Now with a 24 p projector, a frame at 1080 line resolution is drawn (rastered) on to dlp matrix for a 2:4 pulldown for a 50hz projector (1080p/50fps) or a 2:10 pulldown for a 120hz projector (1080p/120fps).

Remember the flicker problems with the cga/ega/Hercules monitors? Flicker problem was solved with non-interlaced high refresh rate VGA and its subsets (SVGA, XVGA, etc.)

But the 24 fps still gives jitter with action pans because the number of frames are less for smooth motion. This is why 100 and +100 is required for video games: for smooth motion of rendered frames, as and when the POV of the rpg player changes. Stabilizing at 60 fps across the board is a topic out of the scope of present discussion!

Shoot 50/60 fps if you want, but give us the motion blur!
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Old 15th December 2009, 14:42   #43
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I give up
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Old 15th December 2009, 16:46   #44
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Patience, boss.


But the 24 fps still gives jitter with action pans because the number of frames are less for smooth motion. This is why 100 and +100 is required for video games: for smooth motion of rendered frames, as and when the POV of the rpg player changes. Stabilizing at 60 fps across the board is a topic out of the scope of present discussion!

Shoot 50/60 fps if you want, but give us the motion blur!
24 P will give fliker depending on what you are shooting example if the scene is black and white checkered pattern changing randomly then you will see flicker , In natural movements the flicker is not noticed because the delta between two scenes is minimal.

If you are so convinced that 24P is what gives film look you can do a little experiment , take a PAL video capture at ( 60 i converted to 60P) and drop alternate frames with no additional processing and play back to check if you are getting flim look.

Coming to motion blur it also depends on the scene being captured, So for normal real life scenarios 24P is just sufficient and that is the reason motion picture industry selected it. TV standards had different reason to choose different rates.

Video Encoding standards utilize this property to encode videos and that is why you might have noticed bit rate is not constant in encoded video ( H.263 for example)

Now coming to gaming , Th background and foreground are vector graphics and not naturally occurring scenes so a high frame rate is needed ( black and white checkered scene example ) still no game really uses 100+ FPS mostly is is 30 or in some cases 60.
Absurdly high FPS is quoted in graphics card specification because they are used more as a benchmark number.

A lot of processing power is used for graphics calculation and 3D pipeline creation so a graphics card need to ensure that it can give sustained 30 or 60 FPS during crunch situation and a high FPS rate in benchmark gives that assurance.
Use case of video is entirely different.
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Old 15th December 2009, 18:08   #45
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Hi AmitK26

You wrote:
24 P will give fliker depending on what you are shooting example if the scene is black and white checkered pattern changing randomly then you will see flicker , In natural movements the flicker is not noticed because the delta between two scenes is minimal.


True dat! That's why panning aggravates flicker, because the scene is constantly changing, leading to max delta. Some flicker reduction algorithms predict the change in the affected areas and render in-between changes in the affected areas of image, leaving unaffected main elements of the picture which are not changing (background in action scenes, for example).

You wrote:
If you are so convinced that 24P is what gives film look you can do a little experiment , take a PAL video capture at ( 60 i converted to 60P) and drop alternate frames with no additional processing and play back to check if you are getting flim look.


That's what the cheap video cameras do: they drop alternate frames to give a fake 24p but end up with horrendous "jaggies".

Quote:
The Sony VX-1000 and 2000 also offer a slow-shutter feature. Set the shutter to 1/30 and you get a very pleasing, fluid film motion. Supposedly this results in some loss of vertical resolution. Beware, some cameras offer a setting sometimes called strobe or film. This effect is achieved by taking a field out of the video. The result is a film like motion, but it also cuts your resolution in half resulting in ugly alaising (stairstepping). Don’t do it. A common myth is that by shooting with PAL gear you can achieve a film look because it’s 25 frames per second. Although this offers decided advantages if you plan to transfer to film, it doesn’t really make for film motion. Remember, you’re still looking at 50 fields per second. As an example, Temptation Island 2 is shot on PAL DVCAM. It still looks like video.


You wrote:
Coming to motion blur it also depends on the scene being captured, So for normal real life scenarios 24P is just sufficient and that is the reason motion picture industry selected it. TV standards had different reason to choose different rates.


The idea is that motion blur is a given, when your subject is MOVING. A slow shutter speed gives MORE blur, a fast, less. HDTV differs further from SDTV in that it employs progressive scan, which gives a smoother, solid-er image. This might be confusing, but 24p native HDTV footage gives a more solid motion blur!

You wrote:
Video Encoding standards utilize this property to encode videos and that is why you might have noticed bit rate is not constant in encoded video ( H.263 for example)


That is again a given, encoding video for display on a tv monitor from film footage (telecine transfers) involves 3:2 pulldown (2:3 actually) accounting for the varying bitrate.

You wrote:
Now coming to gaming , Th background and foreground are vector graphics and not naturally occurring scenes so a high frame rate is needed ( black and white checkered scene example ) still no game really uses 100+ FPS mostly is is 30 or in some cases 60.
Absurdly high FPS is quoted in graphics card specification because they are used more as a benchmark number.


Actually this covers all the requirements of a graphics card:

Quote
The first 3D first-person shooter game for a personal computer, 3D Monster Maze, had a frame rate of approximately 6 FPS, and was still a success. In modern action-oriented games where players must visually track animated objects and react quickly, frame rates of between 30 to 60 FPS are considered acceptable by most, though this can vary significantly from game to game. Modern action games, including popular console shooters such as Halo 3, are locked at 30 FPS maximum, while others, such as Unreal Tournament 3, can run well in excess of 100 FPS on sufficient hardware. The frame rate within games varies considerably depending upon what is currently happening at a given moment, or with the hardware configuration (especially in PC games.) When the computation of a frame consumes more time than is alloted between frames, the framerate decreases.

A culture of competition has arisen among game enthusiasts with regards to frame rates, with players striving to obtain the highest FPS possible, due to their utility in demonstrating a system's power and efficiency. Indeed, many benchmarks (such as 3DMark) released by the marketing departments of hardware manufacturers and published in hardware reviews focus on the FPS measurement. Even though the LCD monitors typical of present times are locked at 60 FPS, making extremely high framerates impossible to see in realtime, playthroughs of game “timedemos” at hundreds or thousands of FPS for benchmarking purposes are still common.

Beyond measurement and bragging rights, such exercises do have practical bearing in some cases. A certain amount of discarded “headroom” frames are beneficial for the elimination of uneven (“choppy” or “jumpy”) output, and to prevent FPS from plummeting during the intense sequences when players need smooth feedback most.

Aside from framerate, a separate but related factor unique to interactive applications such as gaming is latency. Excessive preprocessing can result in a noticeable delay between player commands and computer feedback, even when a full framerate is maintained, often referred to as input lag.

Without realistic motion blurring motions in video games and computer animations would not look as fluid as on film even with the same frame rate. When a fast moving object is present on two consecutive frames there is inevitably a gap between the images on the two frames which can constitute to a noticeable separation of the object and its afterimage left in the eye. Motion blurring helps to mitigate this effect since it tends to reduce this image gap when the two frames are strung together (the effect of motion blurring is essentially superimposing multiple images of the fast-moving object on a single frame). The result is that the motion becomes more fluid to the human eye even as the image of the object becomes blurry on each individual frame.

Frame rate - Wikipedia, the free encyclopedia

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Last edited by proton : 15th December 2009 at 18:11. Reason: tidied up
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