Yesterday I held my camera up to my eye and saw a tiny spider crawling across the scenery. It was perfectly in focus. I took the lens off and didn't see it on the outside of the ground glass, so it must have been in the inside. It's since crawled out of the field of view. I have not noticed any eight-legged dust spots on my pictures.
I'm inclined to do nothing because it isn't hurting anything yet and I have no clue how to extract a spider without damaging the camera. If anybody has better advice I'm listening.
Hopefully it is not a pregnant female since some species can lay thousands of eggs which hatch all close to the same time;>)
If it is in the VF chamber on the near side of the focus screen, it won't hurt anything to leave alone. Hopefully he will get tired of lack of food and leave to better grazing areas. If not, he will die and will probably not be seen again. Stan St Petersburg Russia
I had a friend who like me had an Olympus OM4ti years ago and was surprised to look in the viewfinder and see a earwig! It must have lived and died in the prism as he never saw it again and it didn't affect anything adversely