In my question's preview, the attached image looks rotated. So, assuming you are able to see it in the real orientation, can anyone determine what is that dust flake type thing on the top, slightly towards the left?

One looks like a dust flake and there's another dot to the left of it?

Note: I wont have physical access to the camera until the weekend.

Is it just a dust flake on the lens or can it be some problem with the sensor? Its a 3 month old Canon 1500D.


3 Answers 3


Looks like dust to me. But, it'd be on the sensor, not the lens.

You're shooting into the sun - and if you're using an auto-exposure mode, then your camera likely stopped down. Stopping down exacerbates seeing the dust in your photo.

Want to really see how much dust there is in there? Stop down to f/16 or f/22, fill the frame with a bright light source, and shoot.

Dust will always be there - unless you have a sealed clean room with which to clean your sensor. The small amounts that you have in this photo are nothing to worry about. Do as we all do and get familiar with the "Healing Brush/Tool" in your image editor of choice.

  • The image is at f13. Stopping down means choosing a higher f number? Nov 13, 2018 at 18:39
  • 4
    @VijendraParashar yes, stopping down means adjusting your fstop to a smaller diameter ( which is a higher f number ). We say stopping because the size of the aperture openings are labeled as fstops, opening up one stop lets twice as much light pass through the lens and stopping down one stop results in half as much light pass through the lens. ( not exactly half and double but close ) Each full stop is a halving or doubling of the size of the aperture. Your sensor appears to be extremely dirty.
    – Alaska Man
    Nov 13, 2018 at 20:04

Dust on the surface of a lens is unlikely to image. Dust or smuts on the lens simply blocks some of the exposing light. A dusty lens induces flare that robs the image of some of its contrast. On the other hand, dust will settle on the protective cover glass that encloses the image sensor. This likely happens when the lens is dismounted or mounted. Tiny flakes of dust on the sensor cover obscure some of the image sensor sights and the result is exactly the example you posted. Check your camera manual for best practice sensor cleaning.


There are several dust spots on your sensor, but the long wiggly looking thing is probably a fabric fiber or small hair on the sensor, or more precisely, on the front of the filter stack in front of the sensor. It is large enough that if you remove your camera's lens and open the shutter using "manual cleaning" mode, you'll likely be able to see it with your unaided eye.

The "dust spots" on your sensor you see in photos taken at higher apertures are actually the shadows of that dust that is sitting on the front of the filter stack roughly 2mm or so in front of the sensor itself. Just as a small, "hard" light source will cast a well defined shadow and a large, diffused light source will cast a very soft shadow so the definition of the dust's shadow is determined by how collimated the light casting the shadow is.

Dust in a lens is generally too out of focus to be seen in an image, although the cumulative effect of lots of dust can reduce contrast and exacerbate lens flare.

It takes a lot of dust and/or damage to the front of the lens to affect image quality. As you move further back through the lens the effect of the same amount of dust will be greater than at the front. In most cases, however, it will still be for all practical purposes not detectable in the images you make with the lens.

Almost all lenses, including expensive new ones, have specks of visible dust inside the lens.

  • 1
    It might also be worth noting that a hair on the back side of the lens can also cast an obvious shadow if it is in front of bright parts of the photo (like the sky), but the resulting shadow is considerably fuzzier than anything I see in this image.
    – dgatwood
    Nov 13, 2018 at 23:55
  • How can these particles reach to the sensor? In the last 3 months, I've only used my camera over weekends and haven't changed the lens too frequently. Even when changing the lens on any dslr, there's a mirror in front of the sensor, so how its possible for these particles to accumulate on the sensor? And how do I get these cleaned? Professional service from canon is too expensive, will have to do it manually. Once cleaned, how do I keep it from happening again this frequently? Nov 14, 2018 at 4:01
  • 1
    @VijendraParashar There's also a shutter in front of the sensor. But things that get in the mirror box/light box can move around when the mirror and shutter are moving and stirring up air inside the camera.
    – Michael C
    Nov 14, 2018 at 4:02
  • @dgatwood So basically you're saying the answer should include, "It could be a hair on the back side of the lens except that's not what a hair on the back side of the lens looks like?"
    – Michael C
    Nov 14, 2018 at 4:04
  • I'm saying it might be worth mentioning what dust and debris on the rear element looks like, even if only to further support how you knew the hair or fiber is near the sensor and not farther away. :)
    – dgatwood
    Nov 14, 2018 at 4:10

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