FPS drops in low light

Discussion in 'SJ7 Star' started by dean, Jan 23, 2018.

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  1. dean

    dean Guest

    Hi guys, need advice about my SJ7.
    Videos recorded outdoors in bright weather are fine, but indoors looks slow.
    1080HD 50fps looks like 5 fps, picture blured and grainy.
    I noticed it depends of light level.
    It seems impossible to make good videos in forest, or indoors, or in evening.
    What setting may improve quality?
    AWB, EV value, Metering? Auto low light, auto ISO was always on.
    Firmware 1.18, memory - SanDisk Extreme PRO 32 GB SDHC (Write Speed: up to 90 MB/s)
    Here's samples :

    Well lit place, but i cannot see any letter on signboards...
    111.jpg



    Just see difference.
    What a terrible picture inside and good enough outside
     
    Last edited by a moderator: Jan 23, 2018
  2. Sulev Svilponis

    Sulev Svilponis Elite

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    Try to turn the Auto Low Light off. You may also try recording in 1080HD 60fps mode.
     
  3. Jason

    Jason Moderator

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    Turn off the auto low light - this works by dropping the frame rate to give more light to each frame.
    Also 50fps is too high a frame rate for low light - you're restricting the amount of light each frame gets.
    Ignore the 60fps advice above, that gives even less light and is irrelevant if you are in the UK and using a base of 25fps.
    Drop the frame rate to 25fps instead - you get twice the amount of light to each frame than you do at 50fps
    If you get too much grain, limit the ISO to 800 or even 400 - it's easier to raise the levels of the shadows in post than fix an overly noisy picture
     
  4. RBEmerson

    RBEmerson Humbled by events

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    The image is over-exposed. The whites are blown out or saturated. The "blurring" is the camera moving slightly from, I believe, right to left. The slow shutter speed contributed to this. The auto low light function slowed the shutter down. You can try shooting scenes like this with auto low light off, picking a fast ISO (higher numbers need faster exposures), and hoping for the best. Tinkering with EV might improve the contrast slightly by under-exposing. In a wide scene like this, changing the focus mode won't do a lot for you. If you want to expose one part properly and don't care about the rest, spot metering is a better bet.

    The SD card type doesn't matter a lot except it has to be C10 or better,

    I don't see any problems with the video clip. The pub interior looks about right. The people walking from the car park appear to be only taking their time. The pan rate looks about right. Too bad the dog didn't come back or a car or bicycle or jogger didn't pass through the frame. At any rate, SJ7 video is not shot at a variable frame rate. Ever. Think about it. Changing the frame rate will speed up or slow down the playback, which remains at a fixed rate.
     
  5. Sulev Svilponis

    Sulev Svilponis Elite

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    Don't ignore the 60 fps recommendation, because many users have complained about poor implementation of the 50 fps mode.
     
  6. RBEmerson

    RBEmerson Humbled by events

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    I'll add my usual camera rant: The SJ7 has no shutter speed or aperture control the user can adjust. Tuning the ISO, EV, etc. give some measure of control, but not much. Quite simply, action cams can bang out novelty "look at it and move on" pictures. Of course, if someone wants to do it, attempting "art" or "quality images", with action cam, go right ahead. People also take pictures with pinhole cameras, "because it's there". But expecting to compete with most point&shoot cameras is going to be ...um... disappointing,

    Your mileage may vary.
     
  7. Jason

    Jason Moderator

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    Your answer for low light is to put less light to each image. Bull.
     
  8. Sulev Svilponis

    Sulev Svilponis Elite

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    My answer was to use mode that is supposed to work better. As many users have complained about flaws in 50fps mode.
    Dean is not complaining about dark image. He is complaining about blurry image. Don't you see a difference?
     
  9. RBEmerson

    RBEmerson Humbled by events

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    There is no difference, only making PAL or NTSC work right.
     
  10. Jason

    Jason Moderator

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    As mentioned in my reply the blur comes from the dropping the frame rate by the Auto Low Light.. I use 25 and 50fps all the time and have no blurriness - even in low light conditions as I do not use Auto Low Light and therefore don't have the camera drop the framerate.

    Did you not notice between the difference inside and outside - both at the same framerate? The lower frame rate also means a slower shutter speed which can be seen indoors because of the motion blur as the camera tracks and pans.
     
  11. RBEmerson

    RBEmerson Humbled by events

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    @Jason 'Splain me dropping frame rates. I get the value of extended exposures but if a video's shot at 60 fps for part of it, dropping to 30 fps isn't a good thing. Additionally, if I edit at 59.94 fps (almost always) and I encounter 30 fps, I'll have to transcode it first, and that isn't a good thing. Is the SJ7 really taking that liberty???
     
  12. Sulev Svilponis

    Sulev Svilponis Elite

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    A motion blur is something, that is appearing on objects that MOVE relatively fast compared to the shutter speed.
    But Dean's first image has all objects equally blurred, both people and steady things in the room (furniture, ceiling etc). This could be caused by the camera shake, not by the motion blur. Read this thread: https://sjcam.com/community/threads/50-fps-modes.2111/
    There AndyLG said, that "But if this is the case, then this is a BUG, because on 60 fps there isn't this problem and more important, at 60 fps the sensor get less light than 50 fps (1/50 > 1/60)".
     
  13. dean

    dean Guest

    thx guys, I believe it's problem with some fps modes and auto-light...
    by the way, here is screenshot from video - 1080p 100fps mode - quality is disgusting! all the frames are same
    did someone use this mode?
    1.jpg
     
  14. Sulev Svilponis

    Sulev Svilponis Elite

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    Looks really awful! Like only few pixels are recorded and most of the image is interpolated of those few pixels...
    Not a motion blur, also not an out of focus lens, just poor FW!
     
  15. RBEmerson

    RBEmerson Humbled by events

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    OK, definitely not 1080 at any fps. Look for a Windows tool called MediaInfo (it's free, it's good). Let MediaInfo report (screen shot is easiest) on what it thinks of the clip. Obviously the resolution is way down, but to what? And why?

    Also, try to recreate the problem. If you find that doing A, B, and C creates the problem, it can be reported and maybe there's a work-around.
     

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