If I understood correctly, base ISO is in full stop steps from the lowest possible ISO setting on my camera. For example if the lowest setting on my camera is ISO 100, than the following table would be base ISO:
- 100, 200, 400, 800, 1600, 3200, 6400
While steps in between like
- 125, 160, 250, 320, 500, 640, 1000, 1300, 2000, 2500, 4000, 5000
would be third-stop "pulled" values, which result more noise than perhaps higher base ISO values (for example 2500 is worse than 3200).
- Did I get this right or missed by a mile, what did I miss?
- Do non-base ISO values generate more noise than next higher base-value ISO stop?
- How do I find what are my base-value ISO stops (is it the lowest ISO value multiplied by 2n)?