Ok, just whacked my tripod and 40d out as we just had another storm go over and thought i would get some lightning shots...
however just bringing the files onto the computer and viewing them, I have discovered I have random single pixels of red, green or blue over the images, in the exact same spots.
Opening with a os viewer and DPP these "random pixels" remain, however if i open through CS3 they are no longer there.
I have never had anything like this before with this camera, and didn't have it happen last week when i used the camera for the same purpose and I haven't touched it since then.
Was shooting with a 24-70mm 2.8L, ISO100, a few 100-150" exposures, then 30" after that, at f11. long exposure noise reduction, noise reduction are turned off...
I can post a grab of the spots if anyone wants to see...
what do you guys think? are these just some data mishaps? dead pixels in the sensor? over heating noise from long exposure?
Red dots in the same place would suggest dead pixels in my experience.When converting through CS3 they will get processed out by the software. I had a XTI that developed a few red dots out of the blue. They can be fixed by re-mapping the sensor but i have no idea of the cost of such repair
This is pretty common, especially with long exposures. Don't sweat it unless there are A LOT of them. As you noted, CS3 (and some other programs) will automatically remove them anyhow. When it comes down to it, you are talking about a handful of pixels out of millions.
bpark42 wrote:
Out of curiosity, why do you think this? In my experience shooting RAW has nothing to do with it.
My guess the person uses ACR in some form to convert the raw image and ACR maps out stuck pixels. If you opened the image in DPP they stuck pixels would probably still be there.
bpark42 wrote:
Out of curiosity, why do you think this? In my experience shooting RAW has nothing to do with it.
Well, I had a few problem pixels in my 10D which don't show up in RAW but I'm using ACR, not DPP. Pretty much as Jerry described it. They only seem to be there when I shoot JPEG.
i had a stuck pixel on a canon 350D, and i read on a dpreview post that you can fix it by cleaning the sensor
... i did not however clean the sensor nor even remove the lens... all i did was set it on cleaning mode, mirror locked up... i left it in that mode for 30 seconds and then shut it down... after i turned it on the stuck pixel was gone..
my explaination is either
1) when sensor is in cleaning mode it is de-magnetized or something to avoid static electricity adhering particles
2) as part of the sensor cleaning, it remaps the pixels...
rami.halim wrote:
1) when sensor is in cleaning mode it is de-magnetized or something to avoid static electricity adhering particles
2) as part of the sensor cleaning, it remaps the pixels...
let me know if that helps
Rami,
Are these statements coming from Canon's white papers or technical service manual?
