10-30-2025 10:51 AM
I shot some RAW images on a Canon 5Ds and some of them have an odd pixel spot. It looked like dust initially, but when I zoom in on it there is something odd with the pixels themselves. I have a number of images with the exact same location, pose, etc. and in some images it is there and others it is not. Sometimes it's in a slightly different location. This card was only about a week old, formatted in the camera. I've tried using DPP4's fix for dust on a dark background and it doesn't work. Anybody know what is happening and how I can fix it?
Here's a snip of my screen showing the spot. In DPP4 it appears more red, but in a basic photo viewer it's just white. Showing both.
11-01-2025 07:56 PM - edited 11-01-2025 07:57 PM
My first thought was dust on the sensor, but that wouldn't move. There is a possibility that something is hanging on the edge of your mirror, and gets in the way when your mirror goes up. If there was something there it could move a little with the mirror's motion, and depending on the aperture used it may not show up at all. You can put your mirror up and check using a loop and flashlight if needed, if something is there it will be very small. I've seen this happen before with a bigger spot in the way. Even if you see nothing, use a rocket blower and blow it out (if you haven't already.
11-02-2025 02:53 AM - edited 11-02-2025 03:15 AM
A hot pixel. You can use RawTherapee or darktable to view the Bayer pattern before the raw file has been demosaiced (which may give you a different look).
The documented method to map out bad pixels from modern cameras like 5D IV and R5 is to run "Clean now".
For older cameras people have reported that a manual sensor cleaning for one minute with lens cap on works. You can try both methods.
11-02-2025 09:32 AM
Thanks! And I did correct the photo by using the clone stamp finally. Before when I was using the light/dark dust tool I think it wasn't recognizing it because it had some red coloring in it. But cloning a source material did work.
11-03-2025 10:25 AM
There are two possibilities a hot pixel or a stuck pixel. The difference is that hot pixels are dynamic and caused by heat. But stuck pixels are static and can appear at any time and at any place on the sensor.
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