How to solve the dust in SLR viewfinder?

Leave him alone if it doesn't affect the imaging. If you want to clean it up and put it into action, you may regret it for a lifetime and the equipment is not well maintained.

Eye mask, the gray in the viewfinder does not affect imaging. The focusing screen outside the viewfinder looks a bit like a CCD on gray, which is a small stain. The ash in the pentaprism viewfinder can be seen clearly.

It is normal to say that the SLR is low-end. It is not surprising that the dust in the high-end market has settled.

Don't try to clean it. Don't do this. Don't take pictures when the wind is strong, because it is a camera with heartache.