Why do the photos taken by Nikon D90 always feel dusty?

There is something wrong with the settings. If it is the first time to use SLR, it is recommended to use fully automatic mode or P mode (program automatic) first, which will be easier to adjust. Just pay attention to adjust the ISO setting according to the light intensity when shooting (the weaker the light, the greater the ISO value).

In this way, you can simply take relatively satisfactory photos, but I still suggest you learn more photography skills and knowledge, especially by reading the instructions and memorizing the various operations and meanings of the camera. Learning and groping will make you more and more satisfied with the photos.

SLR cameras are much more complicated than ordinary digital cameras DC. If the photography technology is not in place, the photos taken will be far inferior to the quality and quality of DC cameras (that is, what everyone calls fool cameras).

It has nothing to do with your camera and lens. This level of camera will never have such a low-level problem. You can rest assured of that.