[dougfrey]

Thanks everyone for your reply, it was the lens hood. Problem solved.

[Docrwm]

I don't have a closeup of the scars on my heavily used , 10 year old 12-24 lens hood. but mechanical protection of the lens is sufficient reason for me. Like the time it and the attached lens rolled off a bench to the concrete floor of a horse barn. I keep a broken hood from a Tamron 28-75/2.8 to illustrate that point to my Basic Photography students. The lens survived and a new hood was about 13 USD.

Plus the image contrast is better.

No one has ever seen me working in or outdoors without hoods on my lenses and a small piece of gaffer tape to make sure I don't lose them. It's a working habit, like putting batteries in chargers when returning from a session and downloading memory cards to 2 drives or checking camera settings at the beginning of each session.

That -

[UncleVanya]

I'll bet you a nickel it's the hood not on properly.

You were right.