I have recently discovered 5 instances of images where a single pixel row is discolored, kind of what you experience with hot pixels.
What I find weird about it is that if I look at the position of the row, it is not the same row in any instances, like you would experience with hot pixels.
Also, it seems to happen at random. I can’t really draw any conclusions based on only 5 instances, but here are the facts I have been able to gather so far:
- All images were taken with a Canon EOS R, with the latest firmware (v.1.8)
- All images are shot in RAW (.CR3)
- One image were taken with a Tamron 150-600mm VC G2
- Four images were taken with a Tamron 70-300mm VC
- A couple of EF and RF lenses were used in the same period, but without incidents.
- Both lenses and camera has been used together for a couple of years without incidents, then the first instance occurred on July 14th 2021, one on the 25th and then 3 on the 28th.
- The occurrences happened on 3 different SD cards, although all were SanDisk Ultra 32GB.
- In some cases I have been tracking an animal for a while, in others more or less just brought the camera to my eye, composed and focused and the taken a single shot.
- The five instances are out of approximately 2400 images. In some cases I have 4 or 5 images taken within a second (according to EXIF), and it just happens at random at one of the images in the burst.
- The line does not always have the same colored, but is mostly magenta. It seems to change colored depending on the colored it should have had.
- The line is sometimes only around a quarter of the image width, in other almost all across the image.
- The lines are visible when viewing the RAW file directly from the SD card on my PC, so it isn’t something that happens during import.
Please notice that these are crops of the affected areas, they are not cropeed at the same size and the lines are not at the same position in the images.
As it is not the exact same pixel row every time, I suspect one of these causes:
- Buffer corruption. (either internal memory or when writing to SD card)
- Sensor overheating.
- Firmware problem (as first occurrence were after the upgrade to firmware v.1.8)
- Bad SD cards (although it seems unlikely to happen to 3 different cards within 14 days)
- Lens compatibility (which I also doubt, as I have used both lenses with this camera for 2 years without incidents)
I did notice that when turning on the camera with the lens hood on, that a couple of hot pixels were visible on the display. I then took of the lens, put on the mount cap and did a sensor clean without a lens mounted, which makes the camera map out hot pixels. As expected, the image on the display were perfectly black afterwards. This MAY be a factor, but remains to be proven.
Does anyone have a qualified guess as to what could have caused these issues?