Will I gain something from underexposure?

Started 2 months ago | Discussions thread
Doug Haag Senior Member • Posts: 2,535
Re: Will I gain something from underexposure?

amit190 wrote:

Doug Haag wrote:

amit190 wrote:


For a given scene , shutter must be 1/200 ,aparture must be 2.8 .

For normal exposure (0) -auto iso is 1000.

Will I get better results by underexpose and add exposure in post?

(Camera is a7c if it helps)


If you are talking about adjusting the iso to a smaller number, IMO it will not change the exposure. That's because exposure is not affected by iso. Iso dictates the mapping of the data to produce the brightness of the final result, but does not in any way affect the data that is generated by "exposing" the sensor to a given amount of light. The image will be "exposed" identically at 1/200 and f/2.8 in either case.

I dont understand.

If I lock 1/200 & f2.8 , the exposure will be different with ISO100 ISO500 ISO6400 . , I will overexpose by increasing it.

You are posting in the Beginner forum for a reason.  For those who use photographic terminology accurately, "exposure" means the amount of light reaching the sensor.  The aperture and shutter speed do control that.  But ISO does not.  ISO is a function that "maps"  or interprets the data generated by light hitting the sensor afterward.  That "mapping" or interpretation of the data DOES affect the brightness of the rendered output.  But brightness is not exactly the same as "exposure", regardless of how some people here misuse the term.

At the beginner stage it is probably OK to think of anything that affects the brightness of the output is "exposure".  But at advanced levels of photography, you can reach incorrect conclusions by  not being precise in your understanding of the elements that do and do not expose the sensor to light.  It is kind of like the stroking techniques taught to beginning swimmers.  They are perfectly OK for getting you from one side of the pool to the other without drowning.  But I can tell you from experience that if these stroking techniques taught to beginners are not modified, you will not be competitive at higher levels.

So if you want to eventually progress beyond beginner photographer, understanding why the effects of shutter speed and aperture are quite different from the affect of iso will become important.  If just want to take snapshots, you can ignore everything I just wrote.

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