I've been out getting used to my new Sony kit - a big change from film but I'm enjoying it!
I was really impressed with the camera's long exposure ability (on a tripod at low ISO) until I tried my bargain Minolta 28mm f2.8 in low light. Attached is a small linked copy of the problem image, unfortunately the problem doesn't really show up at this resolution so I'll try to explain.
Basically, as the sky darkens around the bridge, the graduation between tones isn't at all subtle, like shaded rainbows or bands. Examining the pixels in Photoshop at 100%, it looks rather blocky.
I can see a potential problem in the image, the bright floodlight on the left does seem to be causing some flare, could this be the problem? I've had good results from this lens in in other situations but this is the first time I've used it for an exposure over 1 second. Also, I was using Cokin ND grad and I'm wondering if this may have contributed to the problem.
Exposure setting: 30 seconds at f11, ISO 100, dynamic range, noise reduction, sharpening etc off. I try not to push this lens and keep it at f8 - f11 to avoid diffraction problems.
Any advice would be much appreciated.