The scratch right below the reflecting mirror on D600.

At about 1800 shots:

Thing is that when I read this thread last week I couldn't see any mark, but a couple of days ago I started to notice it, and today it is way more visible.

About 10 spots or so appear at a pace of about 500 photos or so. Simply blowing air leaves the sensor clean, so it is not oil.

Local dealer has offered me a change for a new body, that should arrive next week or so.

Saludos!

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Please, excuse my poor english...