1

Snapping with a Canon EOS 600D in narrow DOF situations (for example with low f-stop numbers at long focal lenght), I get ghosting artefacts on the parts of the photograph which are out of focus.

These artefacts consist of the same light-reflecting object showing up not just blurred, but multiple times.

This is an example of such artefacts: example picture

The nature of the artefacts (objects showing up multiple times) suggest a defect (or a quirk) of the optics, where adjacent inbound rays take diverging paths and end up in multiple places on the sensor; however, I have never seen the phenomenon before and I'm not sure of the aforementioned explanation. Has anyone observed this? What could it be?

  • 1
    What lens are you using? – scottbb Aug 29 '19 at 13:44
  • 1
    And do you have any filters on your lens? (If so, take them off and see if the problem disappears!) – Philip Kendall Aug 29 '19 at 13:59
  • That image looks like a crop. Can you add a full image? – xiota Aug 29 '19 at 14:05
1

This appears to be caused by ring-shaped / bubble / donut bokeh produced by your lens, which has soft or nearly transparent central areas and a strongly defined outer ring.

So rather than a soft Gaussian-like blur you might get from more pleasing smooth bokeh, long edges of high contrast (such as the outlines of leaves, branches, etc.) in the background appear almost as slightly blurred double images.

See also:

| improve this answer | |
  • Reminds me of this lens I saw this morning - dpreview.com/news/0739310847/…? – Tetsujin Aug 29 '19 at 14:09
  • 1
    @Tetsujin The swirly bokeh effect was all the rage a few years ago. Lomography produced the Petzval lens (which is just an old lens design with uncorrected Petzval curvature). – scottbb Aug 29 '19 at 14:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.