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I'm using a Sony Alpha A58 and I am shooting at 25 fps. My settings are ISO 200, F5.6, 1/50. The video is noisy in general but more in the darker areas such as black wall e.t.c. Any ideas? Thanks!

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  • \$\begingroup\$ To the downvoter, your downvote was recorded as the following: "This question is about video in a context that is not likely to be relevant to still photography." Why the output of a camera can be noisy at ISO 200 is just as relevant to shooting still images as it is to shooting video, perhaps even more so since the frame rate of video tends to average out shot noise. Still images do not enjoy that advantage. \$\endgroup\$
    – Michael C
    May 20, 2021 at 9:49
  • \$\begingroup\$ Does ISO 200, F5.6, 1/50 give a correct exposure when shooting a still image of the same scene? \$\endgroup\$ May 20, 2021 at 10:14
  • \$\begingroup\$ @RalfKleberhoff Perhaps the real question is something like, "With the highlights properly exposed at ISO 200, f/5.6, and 1/50 how many stops darker are the shadows in the scene?" \$\endgroup\$
    – Michael C
    May 20, 2021 at 18:32

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Noise is not caused by a certain ISO setting. High ISO isn't really what causes increased noise. The lower amount of light we usually allow into the camera when using higher ISO is what causes noise. If you limit the light to the same level at ISO 100 that you would use to properly expose for, say ISO 3200, and then try to boost those almost black shadows by five stops in post, you'll see the same thing as using ISO 3200 with the same exposure time (Tv) and aperture (Av) when shooting. If you're using an older camera, underexposing five stops at ISO 100 and then boosting by five stops digitally in post will result in more noise than shooting at ISO 3200 would. You'll also have more quantization errors.

For more, please see:

Why would using higher ISO and faster shutter speed yield more noise than using lower ISO and slower shutter speed?

Should higher ISOs really be preferred (all other things being equal)?

Regardless of whether you are shooting still images or video, if you want to decrease the amount of noise in a shot you need to increase the amount of light you're letting into the camera. The options you have for doing this are:

  • Use a wider aperture
  • Use a longer exposure time
  • Add light to the scene
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Understand that the noise is primarily a function of a lack of light recorded... i.e. 1/50 @ f/5.6 and the available light level. And darker portions of a scene will always be noisier because they contain/emitted less light; the ISO setting only makes it more/less visible.

Definitely do not underexpose (record less light) and recover in post; that will only make it worse. If possible overexpose (larger aperture) and recover in post as that will help (more light). But it's often easier to just expose "correctly" while also collecting more light (wider aperture or adding light).

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  • \$\begingroup\$ Overexposing might be a good idea if the camera can record in S-Log3. But I couldn't find out if this one can. Probably not, which means it's best to expose correctly. It seems to use only 8bit for luma (and chroma), so there's not much to work with in post. \$\endgroup\$
    – Matt
    May 20, 2021 at 17:28

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