Fast lenses, and High ISO

Started Jul 18, 2014 | Discussions thread
EinsteinsGhost Forum Pro • Posts: 11,977
Re: You missed the question.

jonas ar wrote:

EinsteinsGhost wrote:

Because a competent photographer knows exposure is not dependent on format. It is dependent on: ISO, Aperture and Shutter values for a given scene brightness. That is it.

According to wikipedia photographic exposure is the amount of light (the image plane illuminance times the exposure time) reaching a photographic film (and you may substitute film with "sensor" if you like).

I can see how the aperture and shutterspeed (and the scene brightness) affect the exposure in this defintion, but please do explain how ISO affects the amount of light reaching the sensor. Or do you not agree with wikipedia on the definition of exposure?

I am surprised you didn't ask bob this question. He can make a lens faster by using a different ISO. I can't.

That being said, there is a place for ISO setting. Exposure by itself is only time value (shutter speed) and aperture value. However, how much (and for how long) an exposure is needed also considers "ISO".

Can you not see that changing the ISO is fundamentally different from changing the amount of light recorded?

If you still disagree with my point above, tell me how you use ISO, or if you don't use it at all.

Do you really think that we change the exposure when we use the exposure slider in raw processors (or modulate the image brightness of the developed picture in other ways by software)?

You compensate for exposure differences by doing so. You make those adjustments since you realized that the image was either under-exposed or over-exposed to achieve what you wanted. Any other reason you use that slider?

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