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I get this spot in my images, on Sony A7III

shot data: 0,8" second, F/36, ISO3200. Focused at closest point.

Full Frame:

full image

Frame crop:

spot detail

As seen here, the spot is caused by dirt on the sensor:

enter image description here

I tried internal autocleaning, then using an air blower w/ camera pointing downwards, but it's been useless. What kind of dirt causes this particular spot? And what cleaning technique would be the appropiate for it?

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    Could be pollen or something like that. You basically need to do (or get done) a professional swab cleaning. See this article by Thom Hogan on sensor cleaning. – StephenG Feb 28 at 0:14
  • @StephenG thanks, I've seen that question previously. It certainly helps, but my question is about identifying the kind of dirt in order to choose the best cleaning method. – Lisan Feb 28 at 0:46
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What it might be

With any mirrorless camera that does no close the shutter on lens changes, you will end up having dirt on your sensor occasionally. While I cannot say, what kind of dirt you have there, I would guess it to be a little piece of skin flake as it seems to be translucent.

Tips for preventing dust from getting on sensor

  1. Hold your cam and lens mount downward, when changing lenses, so that any dirt rather falls out of the cam

  2. Check your sensor periodically for dust with an illuminated magnifier.

  3. Always keep either a lens or lens cap on the camera body.

Tips for Cleaning

  1. If you see something, it is almost always too late for the in-camera vibration method. Then remove lens, hold mount downwards and use an air blower.

  2. If that does not help, try a lens brush, then blower.

  3. If that does not work, use a speck grabber (a kind of stick with some sticky gel on one side). With that you just collect the speck and then transfer it to some sticky material which came with the stick. Note: Some people do not trust these, I succeeded in keeping my sensor clean until now using them.

  4. If that does not work, you need to use a moist sensor swab on it. Note: The sensor itself is under a layer of glass, so you cannot damage anything unless you are really reckless or use way too much cleaning fluid.

| improve this answer | |
  • In my experience, the IR filter on the sensor is extremely sensitive to damage. I would be very hesitant to use a lens brush. – icor103 Feb 28 at 18:16
  • While the layers of modern camera sensors might vary, the top most layer of most common interchangeable lens cameras is just glass. See here: extremetech.com/electronics/… – Kai Mattern Feb 29 at 10:08
  • The only sensor swab brands I could find in my national markets are JJC and VSGO. Are these reliable? – Lisan Feb 29 at 21:01

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