That problem is in the middle of the sweep the camera decided to change the exposure and that exposure shows up as the line visible in the tree. The line is even more obvious in the full photo
This elicited a response from a Facebook (on facebook too, this would have been a great comment on the article!) friend:
I’ve read your article “Sony A55 – One Defect. [sic] Was the camera on Manual mode that time or at Aperture mode?
Ron raises a good question and here is the answer.
The Envelope Please
The answer is the sweep mode setting is mutually exclusive of the exposure modes. Simply said, the sweep mode is a setting on the same dial setting you use to put the camera into manual, program, aperture priority, or shutter priority. So, the camera essentially goes into full program mode as far as setting the exposure in sweep mode.
The Cost of Choice
Of course, fixing the exposure over a wide panorama will mean YOU must choose the exposure and that forces YOU to pick which part of that panorama to feature. It is easily conceivable a given panorama will present a range of exposure needs and in my example if the camera had continued with the initial exposure things may have been overexposed in the left side; and it is the left side’s exposure I prefer.
Thinking about this and it occurs to me it is possible this is what I am seeing: that the exposure is fixed, but the lighting is what changes. However, if that were the case, I don’t believe we would see the sudden transition in exposure. The camera is unable to seamlessly blend two adjacent photographs and something is different and there it is NOT the lighting. In any event I think this is a problem Sony engineers need to revisit if they are not already working on it.