View single post by jk
 Posted: Sat Mar 27th, 2021 00:04
jk



Joined: Mon Apr 2nd, 2012
Location: Carthew, Cornwall, United Kingdom
Posts: 6601
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The why is down to experience using any technique.

Remember there isnt a correct exposure only an exposure!
An image that is rendered as a high key image is exposed differently to one that is rendered as a low key image. In the high key image you will be shifting (increasing) your exposure of mid-grey towards white and the reverse if you are exposing to give a low key rendering.

The light falling on the subject as measured by incident light metering will allow you render whatever is there as mid-grey, white or black at whatever is its true tone.  
With reflected light metering a dark subject will fool the meter and give you more exposure and conversely a light object will give you a suggested reading that is underexposing the subject.

Try reading a tutorial on the Zone System.  
Sometimes it is easier to experiment and see than try to explain this stuff.

https://photography.tutsplus.com/tutorials/understanding-using-ansel-adams-zone-system--photo-5607



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