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!
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:
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
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).