ISO doenst change the “brightness” of an exposure. Changing the ISO requires changes to either shutter speed or aperture to give the exact same EV or “brightness.” The only effect on the picture itself should be increased noise, more depth of fiel

In the above example, at aperture of f/3.5, shutter speed of 1/125th of a second and ISO 200, if you were to increase the ISO to 400, you would need twice less time to properly expose the image. This means that you could set your shutter speed to 1/250th

Key Points To Remember About Exposure, Aperture, ISO & Shutter Speed. Use a large aperture value, like f/2.8 or f/4 to get a shallow depth-of-field. This can help you separate your subject from the background. Keep the ISO as low as possible to avoid