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Video shooting help

Jun 5, 2012 11:41 PM

If this isn't the place to ask this, feel free to redirect, although any help would be appreciated. Using a Sony Nex 7, shooting 24fps, 1080p my question is how crucial is it to keep the shutter speed at 1/25 or 1/50 sec? Let's say I want to control my Aperture, either to get a very narrow DOF or one large enough to be sure I nail the focus. I can try and control the ISO to achieve a correct exposure, but, particularly if I don't have my ND variable filter, I may be shooting at a significantly faster shutter speed. To what degree does this pose flicker problems, and how correctible are they in PrP? How would you do so? Also, is a multiple of 1/25 more likely to give a decent video than is one which isn't a multiple, such as 1/320 sec?

 

Thank you

 

kdoc

 
Replies
  • Currently Being Moderated
    Jun 6, 2012 5:44 AM   in reply to kdoc2

    [moved to lounge]

     
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    Jun 6, 2012 6:51 AM   in reply to kdoc2

    Not sure you'd have a shutter speed of 1/25 or 1/50 shooting at 24p. Did you mean 25p...?

     

    At any rate, what happens when you lower the shutter speed is you end up allowing more light in and a side effect is that you increase motion blur. Objects in motion in the frame will be smudgy. Opening the shutter would be better for things like a nighttime exposure where you need more light and there is NO motion in the picture. You might use a slower shutter speed for recreating a crime scene, where you're emulating a "dream sequence" type effect and want the motion blur and reduced implied frame rate of a slow shutter. You will almost always need to use an ND filter when operating at the very lowest shutter speeds under normal lighting conditions.

     

    Faster shutter speeds are going to reduce the amount of light you get into the sensor but reduce motion blur, with highest shutter speeds delivering an almost strobe-like appearance (think about some of the action war epics of the last 15-20 years, with bullets flying, soldiers running around, etc). If you were shooting a soccer match or football game, higher shutter speeds could deliver an excellent image so long as you maintained enough light.

     

    So generally speaking, you DON'T want to mess with the shutter speed too much in terms of trying to use it as an exposure control, because it affects the picture in such noticeable ways. Obviously an iris or ND filter affects ONLY the luminance values on your image with no other noticeable effects (again, speaking in generalities).

     

    You're not usually going to see flicker "problems" unless you're shooting a television monitor or working under HMI or flourescent lighting since there are so many variations in the frequencies those all use (you always want to match your shutter in those instances with direct multiples above not below, and you wouldn't want to mix frequencies).

     

    As for correcting the flicker/strobe artifacts of a FASTER shutter speed, you really can't. Same for slow shutter...the motion blur created by the slower shutter speeds are not fixable.

     

    As for shutter multiples that aren't an integer multiplier you won't really see much of any difference, especially up at 1/320. Same rules apply as I mentioned above for higher shutter speeds, nothing else really.

     
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  • Currently Being Moderated
    Jun 6, 2012 8:18 AM   in reply to kdoc2

    kdoc2 wrote:

     

    I thought one would have to round off to the nearest shutter speed, since there's no way to shoot at 1/24 or 1/48 second in most DSLR or other mirrorless cameras, right? What are my options other than 1/25 and 1/50 when shooting 24p? The camera (Sony Nex 7) does allow 60p and 60i, but that poses other problems, doesn't it?

     

    You can shoot 1/24 on the AF100 in 24p. There's also synchro scan in 24p that allows anything between 1/24.0 and 1/250.6, so there's your 1/48.

     

    I don't remember if 1/50 is an option or not in 24p. Now that you mention it, I think I remember seeing that, but not sure. 1/60 is fine for most all shooting modes and many flicker-causing devices.

     

    Nothing wrong with 60p  and 60i. Keep in mind that 60p is really only fully supported in 720 and 60i is exclusive to 1080. Both 1080 and 720 are industry standard in 24p, as is NTSC, so many people sending out footage to multiple formats do tend to prefer 24p, but shooting 720p60 is excellent - and preferable most times - for live action events like sports and such.

     

    I'd recommend checking out this article by Barry Green (he's primarily a Panasonic guy and hangs around DVXUser.com, which was built on Panasonic users but is now much more than that). Barry compares the AF100 and the FS100 and image-wise you'll see they compare favorably. It's some other non-image-specific issues that tend to make the AF100 a better bargain.

     

    http://www.dvxuser.com/V6/showthread.php?260461-FS100-and-AF100-compar ed

     
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  • Currently Being Moderated
    Jun 7, 2012 3:27 PM   in reply to kdoc2

    For a video look, shoot 30i (there technically is no such thing as 60i, that term is a misnomer).

     

    For a film look, shoot 24p.

     

    Both have their uses.

     
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  • Currently Being Moderated
    Jun 7, 2012 5:50 PM   in reply to kdoc2

    Christian's post was very comprehensive, not just about buying a camera, but about options..whether yours has them or not.

    my impression is you're not sure what the difference is between video and film digital. video is traditionally ' tv cameras ' for shooting stuff you see on tv ( like football games live ).  film digital is more like film cameras that are now ' digital '... and there's a huge difference between the two....

     

    jim is saying 60i is a manufacturer of cameras using the term incorrectly...misleading users.

     

    the basics is this:

    in the USA ( based on 60 cycle per second AC ( alternating current electricity ) )...the tv cameras shoot 30 frames ( half of 60 ) interlaced for broadcast.

     

    thats what you get for " video "... to broadcast on tv.  its based on the AC current.

     

    film cameras going digital is different. It assumes you have a 180 degree shutter ( film camera mitchell movement ) and typically they shoot at 24 FPS.

    That means ( with 180 deg shutter ) you have exposure of 1/48 sec.

     

    These things are different animals ..and it wouldn't hurt to figure that out as best you can by reading etc....then you can decide what you want to do with the cameras you buy etc... ????

     

    film cameras ( real ones ) DO SHOOT 30 FPS if you make them do that... ( you can adjust the fps and shutter ).  Many pro film people shoot tv commercials at 30 fps so that in the transfer to video it is 1 frame of film for each frame of video ... just so you know that...

    Now that film cameras are becoming digital you have the same " choice "....

    So you see, it depends on what you want as your end product and how you want it to look, and what you want your shutter speed to be.... what you decide to do...( this also has to do with how much LIGHT you have to expose the shots .. what choices you make... or how much ACTION there is ( see Christian's post ))

     

    there is no simple answer really to your curiosity ...but manufacturers of cameras would have you think it is VERY simple, so they can sell lots of cameras.. its normal...

     

    hence, 60i

     

     
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  • Currently Being Moderated
    Jun 8, 2012 5:04 PM   in reply to kdoc2

    I'd be interested in hearing your explanation of why there's no 60i, technically.

     

    The longhand convention is to list out the horizontal resolution, followed by an i or p for interlacing or progressive, followed by a slash, followed by the FRAME rate (never the field rate).  Like this:

     

    480i/30

    480p/24

    720p/60

    1080i/30

     

    The shorthand is to drop the resolution and the slash, and simply move the i or p after the FRAME rate (never the field rate).  Like this:

     

    30i

    24p

    60p

    etc.

     

    So...60i really means 60 interlaced FRAMES per second (because you NEVER list the field rate), and there just is no such standard as 60 interlaced frames per second.  It's 30 interlaced frames.

     

    You actually can have 60 progressive frames per second, as 60p, but not 60 interlaced.

     
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  • Currently Being Moderated
    Jun 8, 2012 5:07 PM   in reply to kdoc2
    If I make a BluRay disk, I'll probably use 60p, right?

     

    At 720 you can, at 1080 it won't work.  1080 needs to be 30i or 24p.

     
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  • Currently Being Moderated
    Jun 9, 2012 6:11 PM   in reply to kdoc2

    Are you saying that, although the Sony Nex 7 will record AVCHD 60p, 60i and 24p, I can only make a BluRay at 24p?

     

    No.  I'm saying that of those three, Blu-ray can only hold 24p or 30i at 1080 resolution.  (Remember, no such thing as 60i.)  1080p/60 can be recorded with many newer cameras, but it won't go onto Blu-ray as is.  This is not an Adobe or Encore limitation, it's a Blu-ray limitation.

     

    So if you want 1080 on Blu-ray, your best option is to shoot at 24p for a filmic look, or at 30i for a video look, and avoid 60p altogether.

     
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    Jun 10, 2012 6:09 AM   in reply to kdoc2

    kdoc2 wrote:

     

    Are you saying that, although the Sony Nex 7 will record AVCHD 60p, 60i and 24p, I can only make a BluRay at 24p?  Or alternatively, might I shoot at 60p (if that gives me smoother video), and then have Premier or Encore convert to 24p later?

     

    Nope...60p CAN go to 720p60, 720p24 or 480i60, or 480p24. Very versatile.

     

    Any of those formats, by the way, can be published to Blu-ray disc. Only 480i60 and 480p24 will work on DVD of course.

     
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    Jun 10, 2012 6:16 AM   in reply to kdoc2

    kdoc2 wrote:

     

    If, when working with the Sony Nex 7:  60p gives me somewhat superior videos  than 24p (both 1080), and assuming I'll edit in Premier Pro and Encore, which will give me the best BluRay?: 1. Shooting 60p and going to BluRay with this? 2. Shooting 60p and converting in Premier export to 24p?  or 3. Shooting 24p, and staying there in BluRay? (I see that in Premier, if I put a 60p clip into a 24p sequence, it plays, but with the same or greater jitteryness as a 24p shot placed into a 24p sequence--so that doesn't help to smooth it out and give the quality of a 60p)

     

    You are discussing the "jittery" effect of shooting in 24p as though it is inferior to 60p which appears to you to be superior. Be aware, that jittery effect you're seeing is 100% dictated by your style of shooting. 60p has 2.5x more frames than 24p, which isn't so much of a superior/inferior relationship, it's just a consideration based on your style of shooting. Fast moving objects will be updated frame-by-frame only 40% as frequently in a 24p recording as they are in a 60p recording. If you were shooting a track runner going past your camera in 24p, it'd be completely noticeable versus the same shot in 60p. If you are shooting a still motion or slow-pan shot of an open meadow, you likely will never notice any difference at all between 24p and 60p. Again, it's not a quality issue, it has to do with what you are actually shooting and HOW you are shooting it. I've done plenty of fast motion subjects (dancing, running, sports, etc) at 24p and if you operate the camera a particular way, it's not a very big issue at all.

     

    ALSO - if you put any footage in a 24p sequence and have it playing back in real time (not slo-mo), then any footage, whether 60i, 60p, or 2,000p is going to look like it was shot as 24p, there will be no difference whatsoever. The only benefit gained from shooting 60p and putting it in a 24p sequence is that you have about a 2.5x slow motion capability (also you are going to end up with fewer frames overall compared to 60p, which will produce smaller files during encoding, but only marginally so, certainly not a factor of reduction of 40%)

     
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    Jun 10, 2012 6:21 AM   in reply to kdoc2

    kdoc2 wrote:

     

    OK, I understand. As a follow up, is BluRay always 1080, or are some of them 720p/60? Also why does the 30i look so bad on my computer--can't computers show interlaced properly?

     

    Blu-ray can playback 1080i60, 1080p24, 720p60, 720p30 (I think), 720p24, 480i60 and 480p24.

     

    As for interlacing on a computer monitor....if you set your computer's resolution to 640x480, the interlacing might not be so noticeable. Your computer is trying to playback interlaced fields on a progressive monitor that is likely substantially larger than the interlaced footage resolution, and in some cases your particular media player may be trying to playback ALL of the interlaced fields simultaneously rather than in order (in other words, instead of playing back the 60 interlaced fields in their consecutive sets refreshing 60 times per second, it is likely trying to playback all 30 frames with the interlaced fields combined each second). This will give the appearance of coming in the footage, especially noticeable during periods of the video where the fields change dramatically from 1 1/60th of a second to the next.

     
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  • Currently Being Moderated
    Jun 10, 2012 9:30 AM   in reply to kdoc2

    If you have no idea where it will end up then shoot 720p60.

     
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    Jun 10, 2012 2:44 PM   in reply to kdoc2

    can't computers show interlaced properly?

     

    Actually no.  In fact, there are no flat panel displays that can properly show interlaced material.  They all 'deinterlace' it in some fashion as flat panels can only show progressive signals.  If you want proper interlaced display, you'll need an older CRT for that.

     
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  • Currently Being Moderated
    Jun 10, 2012 2:49 PM   in reply to kdoc2

    if my final destination is not entirely known, and may be variable, in what format should I shoot and what format should I edit?

     

    I'm facing a similar situation with a documentary series that will be published to the web, Blu-ray and DVD.  I decided on the 720p/24 format because the frame rate is usable for all three delivery mediums without any frame rate conversion, and that's always a good thing.  I chose 720 instead of 1080 because the primary delivery channel is via web, and you really need a 50" or larger set to see any significant difference between 720 and 1080.  Since very, very few people view the web on a 50" set, 1080 was less important for this project.  And with a smaller raster, you can get a better image at any give bitrate.

     

    If the primary were Blu-ray, I would probably choose 1080p/24 instead.

     

    As for what format to edit with?  The same as you shoot with.

     
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  • Currently Being Moderated
    Jun 10, 2012 4:01 PM   in reply to Jim Simon

    Remember that shooting at 1080 still gives you excellent reframing capacity for all formats including 720  Blu-ray.

     
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    Jun 10, 2012 8:50 PM   in reply to kdoc2

    1080 60p will give you the best quality and the most options down the way. You can always downres to 720 on export, and if you end up exporting it as a 30p file for Bluray it just drops every other frame, so looks as good as if you've shot it at 30p.

     

    Larger file sizes, but if I didn't know how a project was going to be output, I would err on the side of shooting at better quality than I needed rather than the other way round. Plus any slo-mos you do will always look better if there's more frames to work with to begin with.

     

     

    Jim Simon wrote:

     

     

    Actually no.  In fact, there are no flat panel displays that can properly show interlaced material.  They all 'deinterlace' it in some fashion as flat panels can only show progressive signals.  If you want proper interlaced display, you'll need an older CRT for that.

     

    Your average computer monitor can't display interlaced material, but there are plenty of grading quality broadcast flat panels that can emulate CRT interlacing.

     
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    Jun 11, 2012 6:38 AM   in reply to Christian Jolly

    1080 still gives you excellent reframing capacity for all formats including 720  Blu-ray.

     

    True I suppose.  But I prefer to do my camera work in the camera, and not in post.

     
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  • Currently Being Moderated
    Jun 11, 2012 6:41 AM   in reply to SimonHy

    if you end up exporting it as a 30p file for Bluray

     

    You can't put 30p on a Blu-ray, only 30i.

     
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    Jun 11, 2012 2:08 PM   in reply to Jim Simon

    Jim Simon wrote:

     

     

    You can't put 30p on a Blu-ray, only 30i.

     

    Hmm, how strange. I live in PAL land, we don't deal with 60/30 much. My point still stands, it's easy to make 60p into 60i. And a 30p movie converted to 60i is effectively still 30p.

     

    I don't really agree with your "there's no such thing as 60i" either. It might be standard practise never to list the field rate where you are, but the convention here is to talk about 25p or 50i. Frankly I think 50i is a much better way of putting it, as there are 50 intervals of time recorded, so it's a more descriptive phrase.

     
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  • Currently Being Moderated
    Jun 11, 2012 4:45 PM   in reply to SimonHy

    the convention here is to talk about 25p or 50i. Frankly I think 50i

     

    Nope.  Even in PAL land, it's 25p or 25i.  There's no such thing as 50i either, because following the convention, that actually means 50 interlaced frames per second, and there is no such thing.  So if a lot of folks there say 50i, then a lot of folks there say it wrong.  (Just like here.)

     
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    Jun 11, 2012 5:14 PM   in reply to Jim Simon

    What a strange way of looking at it. Convention just means"custom", it's not some sort of hardwired rule of the universe to NEVER list the field rate. If it's the custom here to talk about number of fields, then that's the convention and people aren't wrong for using it that way, you're just choosing to interpret it that way. Plus, as I said earlier 50i, meaning 50 interlaced fields, is a better summation of what's really happening with the footage.

     
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