Jakov, being my D700 and a not very good period in my life , probably some of both but heavy odds on the sensor
. I have spent more time cleaning the sensors of the D700 and D3S than all of my other cameras combined.
This was taken at the same time at 70mm which begs the question ... did I spend more time cleaning up the image or get a cleaner part of the window
. This was taken from the 19th Floor.
I often thought about taking a tripod on one of my bi-weekly medical trips but normally travelled with hand carry only. For night shots you would need to hope for no pollution or , being you, turn the pollution into a plus for more unusual images
Cheers,