I realized that a dead pixel on my M8’s sensor is causing a vertical line to be visible in high-ISO shots. It’s not visible below ISO 1250, though, so in good-to-mediocre light it’s not much of a problem. The dead pixels don’t bug me either, as they aren’t visible normally, but this line is, even in web-sized pictures. (The line is near the right-hand edge of the frame.)
As you see, it’s only slightly visible, but it is annoying. I will get in contact with customer service in Solms, and I hope that this problem can be solved by mapping the dead pixels (as another L-Camera Forum user suggested), and that the sensor unit doesn’t need to be changed. (After all, the sensor is working perfectly apart from this.)
UPDATE: Another L-Camera Forum user suggested that I try the Pixel Fixer software, with which you can map hot pixels and ‘repair’ your RAW files. What can I say – I got rid of the problem! It even found two more hot pixels, and with specifying which pixels cause the vertical lines (I did indeed find another one at close inspection), I successfully removed the pixels as well as the lines from my DNGs. Great software! Depending on what answer I get from Leica Customer Service, I might continue fighting aberrant pixels with this software – it is probably much cheaper than having my M8’s sensor replaced.
UPDATE 2: Leica Customer Service replied to my inquiry, estimating they’d have to charge me approx. 120 € for mapping the faulty pixels. Whilst probably being much more affordable than having the sensor unit replaced, I think the most economical way to deal with this problem is to continue using Pixel Fixer unless more faulty pixels start appearing. Maybe in due time my M8 is going to need to be serviced anyway, who knows.