Can anyone explain this? I get a light band across the lower third of the frame. My shots are frequently overexposed too (compared to what the histogram shows). I bought the camera used (on this forum) and I'm wondering what to do? E-P3    ---    20mm    f/6.3    1/320s    ISO 800 E-P3    ---    21mm    f/7.1    1/800s    ISO 200 E-P3    ---    21mm    f/7.1    1/800s    ISO 200 Thanks for any help!