I have those little particles on my pictures. There are a lot of them, as you can see, and they have different weird shapes:

Full picture Zomm on the stains

I already sent my camera for a sensor cleaning and the guys at the shop told me that those particles are under the first layer of the sensor and they can't be removed. Is this possible or are those stains some kind of stuck or dead pixels? The camera is only two months old, and I don't really know what those things are.

  • \$\begingroup\$ What makes you doubt the camera shop? And, is the camera under warranty? Was it the manufacturer's recommended service center, and did they deny a fix or replacement under the warranty? \$\endgroup\$
    – mattdm
    Mar 29, 2014 at 12:19
  • \$\begingroup\$ If this dirt is really under the top layer of the sensor, then you should get the camera replaced under warranty. \$\endgroup\$ Mar 29, 2014 at 13:14
  • \$\begingroup\$ Thx for the info, is not that i doubt the camera shop i'm just wondering cause i don't really know a thing about sensors. I'll contact canon suport to see if something can be done. \$\endgroup\$ Mar 29, 2014 at 13:20
  • \$\begingroup\$ The photos appear to be consistent with the camera shop's diagnosis. \$\endgroup\$
    – Michael C
    Mar 29, 2014 at 14:13

2 Answers 2


One way to tell if the sports are on the sensor itself, or on the AA layer above the sensor, is to shoot a white background at wide aperture (say F2.8) and one at narrow (say F22).

To understand the point, consider how a shadow is cast. If the light is a near point source (F22) then it's a sharp shadow. If the light is diffuse (F2.8) then there's no or little shadow, which is why people always say check for dust at high F stops.

So if you take one high and one low, if the specs are on the AA layer (well above the sensor) the F2.8 shot will show no or very diffuse spots. If they are instead on the sensor itself, they will be almost he same. If they are on some intermediate layer you'll get half-way shadows.

To actually tell, perversely enough, you might want to put a hair or spec of dust on the outside of the sensor (i.e. above the AA layer) and compare how it looks at F2.8 and F22, that will give you a good feel for where these are.


Does this camera happen to be the Nikon D800? It's not quite consistent with the common 'oil/dust spots' as can be seen here, yours are more squiggly. But these have (as to my knowledge is Australia) have a warranty fix for it.

The repair centre may be right, however it's important when they told you. If it was:

  • When you gave it to them and gave them image examples

and the straight away said it's under a layer and can't be fixed (AND didn't charge you), then that's fair enough. If;

  • They attempted to repair it, without image examples

and they told you after and still charged you, this is wear they have a leg to stand on. You should still get a refund. If;

  • They repaired it, charged you and gave you no information at all

and you found out when you went to take some shots after you got it back, then that's a definite refund.

What it true is that image sensors do have layers. They also have filters, generally made out of glass and are IR stop types. Depending on the model, it's highly likely that you can (very carefully) remove the filter and clean underneath it. In some cases, the filter is just replaced because it's easier than to clean.

In the very, very rare case that it's actually caught inside the CCD or CMOS layers, then the image sensor needs replacing and can't be cleaned. Concluding from the inconsistencies from your two images, this is not the case.

Again, this could be a certain model where the filter can't be removed.

It's not a stuck or dead pixel.

If the camera is only two months old, take it back to the manufacturer. You shouldn't be paying for any of this to be fixed.

  • \$\begingroup\$ Then for the info, they didn't charge anything, the camera is a 600d asp-c sensor, i'll do some research to see if its possible to clean under the first layer. Anyway i'll contact de customer support of canon to see if they can do anything. Thx again . \$\endgroup\$ Mar 29, 2014 at 19:22

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