Dirt on the sensor A7SII

[AlejandroGomez]

Hi guys,

 

I was just cleaning the sensor of the A7SII when I saw that a lower aperture you can see all the dirt on the sensor, but if you go up to f1.8 you stop seeing them.

Maybe the question is stupid but I'm figuring out why this happens, theres some technical explanation ?

 

 

[Mark Dunn]

Because the dust is actually on the anti-aliasing filter in front of the sensor, it casts a shadow on the sensor.

At large apertures the shadow is spread over a large area. A small aperture casts a smaller, darker shadow.

https://photographylife.com/why-sensor-dust-is-more-visible-at-small-apertures/

Edited April 27, 2017 by Mark Dunn

[AlejandroGomez]

Hi Mark,

 

Thank you very much for the explanation and the link!

[Daniel Meier]

I used to think that this has to do with the larger depth of field you get with an f/16 compared to say a f/1.8.

Is that true to some degree?

[Mark Dunn]

In short, no.

DoF applies to what's in front of the lens.