Lens Question - Help!

[Utopia]

I just got my Mir-1 in the mail a few days ago.

Beautiful lens. Silver chrome and shiny - best condition I've seen that I could find anywhere - $130.

I took it for a test drive this morning and when I stop it down to 16, I see two minor spots on the lens - bottom right hand corner and far left.

Is this something I should be concerned about?

Granted, this is a 50 year old lens... The listing said it was in mint condition and the lens was very clear and everything, and it is when it's wide open (2.8) but when stopped down around 16, it puts 2 dark spots in the picture.

I don't know what the protocol is on this for lenses - do I need to worry about it? Did I get ripped off?

 

[bird]

I'm not an expert, but could it be dust between the back element and mount? Dust under the lens glass? Finger smudge? Compromised lens coating?...since the lens is older the coating may be degraded. Did you shot any footage we could view this aberration you're talking about?