I know a little about cameras since doing two courses, and so I set my camera on manual setting most of the time to take shots.
I took the following shot in New York of Manhattan at night. Because of the lack of light I used a wide aperture, and a slow shutter speed of 5 sec. (I used 100 ISO).
I rested the camera on a brick of the building as I didn't have a tripod with me at the time. The photo came out pretty well, but I notice that there are dark areas to the sky around the bright lights (especially noticeable around the spire of the building on the right), it became slightly more noticeable once I adjusted the levels in Photoshop.
Please can somebody tell me what causes this and if there is anyway to eliminate this from the photo (either using different camera settings or by adjusting the image in Photoshop)?
Here's a sample image from my site Manhattan at Night: