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What are the spots on the images?

Often dust spots on your images go unnoticed because they are camouflaged by the other details in the picture. However, when come very visible and stand out clearly. CustomerOriginal

When you first notice spots they probably look a little like in the image above. They are typically fuzzy round or irregularly shaped spots, indicating that something on the sensor surface.

Tiny particles enter the mirror chamber when the lens is changed or the camera body is stored without a cap. If you never change the lens, you could go years without noticing spots.

Of course, the idea of an SLR camera is that you can use different lenses, so, eventually some spots will appear.
Minimising the causes of dust contamination will cut down on annoying spots.

The main reasons for dust contamination are:

Once particles are inside the mirror chamber the loose bits will be moved around as the mirror flips up and down and the shutter opens and closes. Inevitably some bits will end up on the sensor surface and in the viewfinder.

… next, how to inspect the sensor >>

Dust specks visible in the viewfinder and inside lenses!

The thing to understand about SLR cameras is: the viewfinder is a unit separate to the image sensor.

This means that specks you see in the viewfinder are NOT the spots that appear on the images!

Specks in the viewfinder are bits, present in the mirror chamber, that have been flipped up onto the focusing screen by the mechanism action.

These bits may be annoying, but they do NOT appear on the image.

The same is true of dust particles you may see inside the front of your lenses - they do NOT appear on the image.

However, larger spots on the rear element of your lens, can sometimes cast shadows on the sensor.
But generally, only particles, that end up on the sensor, will appear on the images.

Cleaning the finder

The focusing screen can, in most cases, be cleaned by very gentle air puffing, but more frequently the screen must be removed.
This is slightly risky and is best done by a technician with the proper tools.

With some camera models cleaning the internal finder requires dismantling, and may not be economical except during other service.

The best way to minimise specks in the viewfinder (and sensor) is to keep the mirror and mirror chamber clean.