This is embarrassing. I've been shooting a D70s for years, using several lenses, and I've never seen this effect -- obtained with a brand new D7100 and a Tamron SP 150-600. Cards are 16 GB SanDisk Extreme 90 MB/s.
I see this effect in about 5 of every 100 shots, taken in various lighting conditions.
Problem_Image.JPG 205.36KB 1 downloadsSwitched the cards and got the same result. Haven't tried changing lenses yet, but I've never seen this using the Tamron on our D70s.
I've tried Googling for help, but nothing shows up, probably because I don't know what to call this effect.
I've attached a small sample -- I'll be glad to get any advice.