Does not show up in photos I take but I see it in the eyepiece.
I know that it is in the lens as I have taken it off and had a look.
If you can see it through the viewfinder it is either on the focusing screen or on the mirror, just use a rocket blower to dislodge it...
and this also! I love these sites!
http://www.lensrentals.com/blog/2011/08/the-apocalypse-of-lens-dust
Then you can start a thread with "Speck of dust on my sensor".