[Leica] Mystery: Sensor Dust & Small f/stops

[michiel.fokkema at wanadoo.nl (Michiel Fokkema)]

Robert Rose wrote:
> I have noticed that at small f/stops (say, f/16), I can see very tiny black
> spots on my M8 images.
> 
> These spots become more like faint circles at mid f/stops (f/8), and are
> completely unnoticeable at wide apertures (f/2).
> 
> [I should add, this is lens independent.]
> 
> So, is this dust on the sensor?
> 
> If so, what physics accounts for the dust being "in focus" and "out of
> focus" as a function of f/stop?  If it is dust, then shouldn't it be
> blocking a region of pixels, independent of f/stop?.
> 

With aperture wide open the spots are more diffuse lighted. Like with a 
soft box. When the aperture closes the light gets more like a spot. Like 
a naked light further away.

Best regards,


-- 
Best regards,

Michiel Fokkema