Emilian Dechev wrote:
But why would I get 3 hot pixels in the first test, and only 1 hot pixel in the second?
Isn't a dead pixel really dead in all occasions? Or maybe it depends on some variables like sensor running time / temperature, exposure, etc
It can depend on few things.
First of all, dead pixels increase OVER TIME. So you might get a camera with apparently very few dead or stuck pixels and none that show up, and later you develop more dead pixels that show up in your footage.
Even brand new sensors have many dead pixels from the factory, before they get installed in your camera.
Every camera has a way of re-mapping or turning off these dead pixels. Usually this works without you even noticing.
Dead pixels are more likely to show up when the sensor is hot or has been on for a while. Again, this goes for any camera.
Most people don't realise on their DSLR that the overheating that can happen, isn't about the camera literally overheating or being damaged, but more that the noise (like FPN) or dead pixels can no longer be controlled in an acceptable way. So the camera suggests or forces you to rest the sensor for a bit. The noise floor rises, and other sensor artefacts show up more readily. I think you'll find somewhere in these threads where some have tested the noise floor on BM cameras in normal operating conditions and in super cooled conditions. It's no surprise that the sensor isn't has noisy when the camera is better refrigerated.
Some companies even do after market cooling mods for special purpose use to stock cameras like astro photography, where a dead pixel could eaily become a new star
https://petapixel.com/2016/10/11/cooled ... ar-photos/So, dead pixels are always there, you just mostly never see them or notice them. If you are, it COULD be a sign that there's an issue with cooling on your camera, or perhaps in some rare circumstances, the dead pixels can't be corrected or turned off. I'd suggest cooling might be the issue in your case if they're intermittently showing up.
You should try BMD service and see what they have to say.
I remember Sony used to say that they wouldn't accept a return under warranty for some of their broadcast cameras unless there was more than 6 dead pixels visible.
If you're lifting them 3 or 5 stops to see them and not always seeing them, I don't think you'll get much sympathy.
JB