Relation between dust and aperture setting

Started Mar 30, 2014 | Questions thread
jfriend00 Forum Pro • Posts: 11,330

LA Headshots wrote:

Photonique wrote:

Hi all,

this is my first post in this forum although I've been reading it since many years. I'm owning a D800 since 4 months now and I am very happy with it. However, I've had increasing issues with dust levels on my sensor. Anyway, my question is not related to how to remove such dust but I made an observation which I can't find an answer to:

When I take a photo of a bright white wall at high aperture number, say f22, I can clearly see a lot of dust particles. But when I set the aperture to f3.5, all dust particles are no longer visible. How can that be? I mean the dust will not change deepening on aperture setting. So it must have something to do with the light entering through the lens and hitting onto the particles. This phenomenon is also clearly visible when using life view mode.

Does anyone know why this is happening?



You spent $3k on a D800 and don't understand how aperture affects depth of field?

So sad.

In all fairness to the OP, this isn't entirely a DOF issue.  It turns out that the same thing that makes larger DOF (narrower angle of collected light rays) also makes the shadow of a dust particle appear more visibly, but they aren't exactly the same thing. One could totally understand the correlation between DOF and aperture and not know why dust shows at smaller apertures.

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