Noise spots on long exposures
Long time reader, first time poster... with a big thanks to the community.
I own a Sony Nex 6 and noticed that long exposures show blemishes that are not visible on short exposures (see picture). I don't know when this started, but it wasn't always the case. Also, I'm quite sure it occurred with several lenses, so the issue seems to be with the camera. I used the built in sensor cleaning function, but to no avail. Any ideas as to the reason and what I could do about it? Going for a short trip to Acadia this Sunday and hoping to have it fixed by then.
Here's an example - you'll see it especially in the sky:
|Moon 99% D55 C14 St-Zénon 20170806 DP by MarioSS|
from Best Picture of the Week
|Reeds on lake by kkardster|
from Abstracts in Nature
|Florence & the Machine by Dutch Newchurch|
from Second chances..