Catpiano

OMG ....   do u have sensor swap??

Or say at least the blower?

You should hv the sensor clean function on your body, if it is not too old model, you can go menu->sensor clean-> clean now, or set to clean when everytime you turn on or turn off the sensor.

However, some case, still need to use the blower or sensor swap, as most the dust on your sensor are pretty big now.

Catpiano

It looks like dirty sensor, you hardly see spots, if it is from the lens, it shouldn't be like that.

First, double check if your camera has sensor clean feature. (most of the DSLR within last 2 yrs have that function) If not, use the little blower (like a ball ball) or use the sensor swap.

If dust on lens? easy...

--> http://www.cameragadget.com/prod ... &products_id=35

Catpiano

D40X ..  then u select to "clean sensor"  ( it will flip the mirror up, and u will see the sensor directly)

Or u can set the time to 30 second, then the mirrow will open up, u can see the sensor, and use a little blower to blow it ..

Try not to use those can compressed air ..  (or need to be very careful)