White dots, One purple dot.

Started May 28, 2012 | Discussions thread
RAYoung
Regular MemberPosts: 160Gear list
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Thanks for the tip!
In reply to photonius, May 31, 2012

Buried in the FAQ's of the PixelFixer web site you referred to is this statement:

"If you shoot raw and process your images using Adobe Camera Raw/Lightroom, Capture One (version 5) or Silkypix, hot pixels will be removed automatically."

Now I don't have Lightroom, but I use Photoshop Elements 6 and it also includes Adobe Camera Raw. So I tried opening a RAW image from my XSi that I knew had some hot pixels and they disappeared immediately. I think that solves my problem.

My situation was this: in the past year I shot fireworks several times and turned off Long Exposure Noise Reduction because I didn't want to wait for the camera to make a dark frame after every shot. That's when I began noticing some hot pixels, maybe dozens of them, in my images. Most of them weren't noticeable unless I viewed at 100%. But after a few tests I could see that my hot pixels showed up under these conditions:

  • exposure time of 5 seconds or more (at 20 or 30 seconds, many more show up)

  • Long Exposure Noise Reduction OFF

  • where there is a dark or black background

With my camera, I never see hot pixels under normal daytime shooting conditions or even low light conditions unless I'm using very slow shutter speeds. So my solution is to process the RAW image with ACR when necessary instead of Canon's DPP, which I usually prefer. Of course, if I can wait for the dark frame to process, I can leave LENR turned on and that eliminates my hot pixels.

I think the other method you referred to about making the camera "remap" the sensor is discussed in this thread: http://forums.dpreview.com/forums/read.asp?forum=1031&message=32123153

If you read through the thread you will see there is debate about whether or not it works. I tried it on my camera and saw no results. One thing nobody mentioned in that thread is whether or not they have Long Exposure Noise Reduction on when they see hot pixels. For some, though, it sounds like they had very prominent hot pixels that showed up no matter what. That is probably a very different problem than mine.

Well, maybe this info is also helpful for the OP. But I did appreciate the tip about ACR!

Roger

photonius wrote:

darkwrld wrote:

I'm getting as the subject says white dots and purple dots in my photos, usually on dark surfaces, even in daylight. I thought it was dust so I cleaned it, moved it to multiple rooms. No clue.

The Camera is a 1100D Canon and is new.

They almost look like stars, which makes me wonder if the Camera has been used before and the sensor has been burnt? Any ideas?

no, that's normal.
Hot pixels
http://www.kenrockwell.com/tech/hot-pixels/index.htm
http://www.pixelfixer.org/

I thought there is also a way to tell the camera to ignore hot pixels (some kind of self-check), but I forgot how, some kind of reset. try google.

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