A few K3iii ISO comparison images

Started 2 months ago | Discussions thread
Richard Smals
Richard Smals Senior Member • Posts: 1,844
Re: A few K3iii ISO comparison images
4

Then .. I don't get it ... Why you can't simulate less light by shortening exposure time? And at the same time increase ISO to get same brightness of the resulting image.

Because the total amount of light remains the same and the amount of light or lack thereof is what causes the noise, not raising the iso. There's a huge difference between reducing the exposure and raising iso to maintain brightness and reducing scene luminance and raising iso to maintain image brightness.

Aperture and shutterspeed is physical changing the amount of light what hits the sensor, changing these variables controls the real amount of light. So in this regard you CAN test noise levels, as the OP does. For example: If the aperture is -5 stops from the spot meting exposure of an object that object become (almost) complete black (See zone system in literature aka Ansel Adams)

I believe that i understand what you trying to say though: In an even lit scene noise is not as dominant as in a night scene with sparse lit objects. But you can create a night scene even from a well lit room: Dynamic range in the scene needs to be great enough though (EV 8 with EV 12 parts). With spot exposure on the EV12 you create a night scene even if its not and it behaves for iso noise as a night scene. This is an example off course. The only variable which can be of an influence is dominant slower shutter-speeds because of heat and "dead" pixels.

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