Grain from a Sony A7iii

Started 4 months ago | Questions thread
FingerPainter Veteran Member • Posts: 9,611
Re: Grain from a Sony A7iii

poipoipoi_2016 wrote:

gezzamondo wrote:

I never used any exposure compansation. Or do you mean when i increased the exposure and shadows in post that would generate grain?



Noise is a relationship between pixel values.

Increasing all the pixel values by the same factor doesn't change the relationship between them. So lightening in development doesn't increase noisiness.

When you increased the shadows and exposure in post, you also magnified all the sensor noise that was happening below the surface by a factor of 5.

Huh? How did you come up with a factor of five?

Exposure compensation is your way of saying "I think your light meter is wrong and I want a different picture than the one you're trying to get me to take". Which then lets you avoid having to do post-processing off bad data.

Close enough.

Also, bracketing, which would probably have saved you here.

To use my test metaphor, what you did was say:

1) Everything between 70-100 is now 95-100

No, If 70 is now 95, then 100 is now 136.

2) Everything between 10 and 70 is now increased and compressed into 50-95.

If 70 is now 95, then 10 is now 14,not 50.

3) Everything between 0 and 10 is now stretched to cover 0 and 50.


Do you understand why #3 would result in noise?

But 3 is not what happens.

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