Relation between dust and aperture setting

Started Mar 30, 2014 | Questions thread
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Alan Brown
Alan Brown Veteran Member • Posts: 4,685
You're both right..

jfriend00 wrote:

It isn't really the dust spots being in focus as they aren't being imaged. It's more a matter of how sharply defined a shadow they form which is a product of how divergent an angle of light rays are being used.

An interesting real world effect that is somewhat similar is that you can shoot sports through a chain link fence and not see the fence at all if you use a large aperture, but if you use a small aperture, you will see the effects of the chain link fence. It's the same concept. If the light rays come from a narrow angle, then the obstacle in the way of the light rays has a more noticeable effect.

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jfriend00 and Dwight  shadow casting and focusing at the film/sensor plane.

it's true that the DOF (depth of focus) on the image plain. film or sensor is also increased making anything there or close to it (dust) come into sharper focus too; as it is with the reverse side of the lens.. Depth of Field (unfortunately also designated with the same initials DOF) is increased with smaller apertures.

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There is a very fine line between 'hobby' and 'mental illness.' :'!':

 Alan Brown's gear list:Alan Brown's gear list
Nikon D3200 Nikon D610 Tamron SP 70-300mm F/4-5.6 Di VC USD Tamron SP 24-70mm F2.8 Di VC USD
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