some help for setting up for video taking please

Discussion in 'Filmmaking' started by adwb, Feb 8, 2017.

  1. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    A couple of questions her from me which I dont understand after looking and looking on google. I did find shutter speed vs shutter frame rate which made things clearer but:-

    I have seen it written that if you have the camera set to auto for the aps-c / super 35 then movie mode uses super 35 but on myA7r2 that does not happen i need to select it manually am I misunderstanding something?

    also for XAVCS there are the two choices of 25p 100M and 25p 60M

    25 is the frame rate ? is that correct ?

    and should be matched to double the shutter speed =1/100 is that correct?

    100M and 60M is the bit rate and 100 M will give a smoother video is that correct?

    if that is then correct then why is there a choice?

    I note that on XAVC S HD there is the choice of 50p 25p and 100p all at 50M compared to the XAVCS which only offer 25p

    So why is there a choice 3 frame rates avaialble for the XAVC S format?
     
  2. bdbits

    bdbits TalkEmount Top Veteran

    749
    Sep 10, 2015
    Bob
    I am not a big video person, but from what I do think I know...

    For 25p the '25' is the frame rate - 25 fps, p for 'progressive' as opposed to 'interlaced' frames. Usually you want progressive even if that means a lower frame rate, and shutter speed should be double the frame rate (1/50 for 25p). They say different frame rates give a different look to the video, but I have never run side-by-sides to see for myself. Oddly enough higher is not always better. I usually see 24fps recommended (what is used for movie film). The argument is that this is what people are used to watching movies in, and the different motion blur and what have you at other frame rates looks artificial.

    The bit rates are more about image quality. Sort of like megapixels for stills, I suppose. The reason for choices relates to file size and the ability to play it back smoothly. It would also matter depending on how you would be delivering the video - over the internet, DVD, Bluray, local computer, etc. If you record at 100M but it will be delivered at 25M, you may have to re-encode the video. You should probably also consider the resolution - 4k video is going to need a higher bit rate to achieve a certain image quality level as opposed to say standard HD, whereas 100M might be super-high IQ for standard HD. But I have not done the math so not sure what the recommended bit rates are.

    And that is about the limit of my knowledge of video.
     
  3. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    I seem to get jerky or stuttery playback in every mode except MP4. if i use 4 k and dual record the mp4 is smooth but the 4k is very jerky no matter how slowly I pan or move.
    even the auto zoom (digital zoom) is smooth on the MP4 but jerky on the 4K.
    I have tried various shutter speeds from 1/50 to 1/200 but and lower as well but it seems the same. Any Ideas what I am doing wrong ?
     
  4. Hawkman

    Hawkman TalkEmount All-Pro

    Sep 10, 2013
    Virginia, USA
    Steve
    Quick question: what are you playing the footage back on? The camera or a PC/Mac? It is entirely possible that if it is a PC/Mac, the computer may not have the power to smoothly play back 4K footage. It takes a fairly new and fast CPU, graphics chip, and hard drive to handle 4K well.
     
  5. roundball

    roundball TalkEmount Hall of Famer Subscribing Member

    Oct 8, 2013
    USA
    Makes me want to ask for verification on a questios as well.
    I get the impression my NEX7 defaults to a particular shutter speed regardless of what speed I might have it set on...
     
  6. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    Probably to old but also maybe i need a steady cam or gimble


    Processor
    AMD Athlon(tm) II X2 250 Processor
    Manufacturer
    AMD
    Speed
    3.0 GHz
    Number of Cores
    2
    CPU ID
    178BFBFF00100F63
    Family
    10
    Model
    06
    Stepping
    3
    Revision

    Memory
    RAM
    16 GB
    Video Card
    Video Card
    NVIDIA GeForce 210
    Manufacturer
    NVIDIA
    Chipset
    GeForce 210
    Dedicated Memory
    1.0 GB
    Total Memory
    4.0 GB
    Pixel Shader Version
    4.1
    Vertex Shader Version
    4.1
    Hardware T & L
    Yes
    Vendor ID
    10DE
    Device
    0A65
    Plug and Play ID
    VEN_10DE&DEV_0A65&SUBSYS_080A10DE&REV_A2
    Driver Version
    21.21.13.4201
    Operating System
    Operating System
    Microsoft Windows 7 Home Premium Edition Service Pack 1 (build 7601), 64-bit
    Service Pack
    1
    Size
    64-bit
    Edition
    Home Premium
    Version
    6.1.7601
    Locale
    0809
    BIOS
    BIOS
    Default System BIOS
    Version
    American Megatrends Inc. 080015
    Manufacturer
    American Megatrends Inc.
    Date
    08/16/32
     
  7. bdbits

    bdbits TalkEmount Top Veteran

    749
    Sep 10, 2015
    Bob
  8. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    this one shows ok Hydrophobic_Paddles_NTV-HIGH_RES_MOV.mp4
     
  9. bdbits

    bdbits TalkEmount Top Veteran

    749
    Sep 10, 2015
    Bob
    OK, that would seem to eliminate your computer as the issue.

    If it was me, I would next try a tripod on a very simple, probably static subject. If that is still 'jerky', I would think it is either a settings issue or maybe the card is too slow on write speed (just an idea). If the tripod is smooth, then maybe some kind of stabilization will be needed when shooting off tripod, as you mentioned.
     
  10. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    thats what I thought ; I will try with a tripod tomorrow and reply, I looking at a steadycam which certainly can't hurt anyway. Thank for the help Bob.
     
    • Appreciate Appreciate x 1
  11. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    well thats disappointing while the tripod pan is smoother the 4k one; compared to the mp4 basic one the 4k one is very jerky, both are ok on static subjects

    I dont think I can post sample clips here
     
  12. bdbits

    bdbits TalkEmount Top Veteran

    749
    Sep 10, 2015
    Bob
    Sorry to hear it. Must be something fixable causing it, as I've seen some very nice 4k video shot with Sony bodies. But I am already at the bleeding edge of my knowledge on the topic. :(
     
  13. adwb

    adwb TalkEmount Regular

    147
    Sep 30, 2015
    Bristol UK
    Alistair
    well it might be the individual player, on some editing software its jerky but others, and using Sony playmemories home you have a save option with smoothing which seems to fix it ?

    its all bit weird and , while for still images there are a million photographers on forums who will help with videography it seems very hard to get advice.

    I thank you you for your kind suggestions and help.

    I down loaded a full video taken on a7r2 in 4k , it took 1/2 an hour but it looks as bad as mine till I smooth it so it's not me but my pc I suspect.