Can Dead Pixels be Sensor Dust?

EDIT--BTW...by dead pixel, I meant hot/stuck pixel (changes made below). :rolleyes:

So an odd spring thunderstorm rolled through at about 11 pm last night. Of course, I ran out to take a few photos. In looking at them this morning, to my surprise, I see hot pixels.


30 sec, f/8, ISO 200, Long Exp Noise Reduction set to auto....I increased exposure +2 in this image to see them more clearly....
http://farm8.staticflickr.com/7055/6...21aeab46_b.jpg
IMG_1964 small by kayaker72, on Flickr

http://farm8.staticflickr.com/7063/6...b4c4d576_b.jpg
IMG_1964 rc by kayaker72, on Flickr

http://farm8.staticflickr.com/7053/6...f485a266_b.jpg
IMG_1964 lc by kayaker72, on Flickr

BTW---processing to jpeg is making them smaller and lose a little of their color. In RAW, they are clearly red, blue, green or white and are very apparent.

The reason I am surprised is that I've tested my sensor before. I have taken 30 sec exposures with the cap on. And I found 3-4 small areas of hot pixels, only visible when really looking for them. Something I could live with. But, nothing like I see in the photo above.

So, the question gets to be, are my hot pixels getting worse or can sensor dust...or something else, cause what I am seeing. The reason I ask is that in ~2 yrs and ~22,000 exposures....I've never cleaned my sensor.

Thanks for any insight. I'll work removing the hot pixels....

In my experience, dust shows up as small dirty blobs on the photo at f/18+. I use this to clean the sensor which does help. I can't say for certain if what you're seeing is dead pixels, but if they are red, blue and green that leads me to think that there is something going on with your sensor.

Brant, I think hot pixels. My old 5D II had a few and most of the time you wouldn’t notice them. But if you did real long exposures or the camera was used a lot it seemed to heat up the sensor and you would notice. Of course they usually appear at the exact same location in the frame when they do appear. I think you are noticing them because you heated the sensor up with the long exposure.

If you want to check dust find something white or sometimes I use the blue sky. Take several pictures and pixel peep on your computer in a pattern across the frame. Dust usually appears as a grayish discoloration but it can look like a solid object if it is big enough. But I have never seen it appear as a bright point of light.

Thanks Photo and Rick....

I agree...they certainly look like hot/stuck pixels. I also just did a test with "Long Exposure Noise Reduction" set to "on" rather than "auto" and that seems to have eliminated them....which would be consistent with hot/stuck pixels.

I guess what is surprising me is that they seem to have significantly multipled compared to when my camera was new....or maybe my testing is better....

My old 5D II was the same way, I had two of the 5D II bodies and the older had gotten several hot pixels. But you were doing 30 second exposures here, and if you did several in a row I could see how it would push the camera to its limit. I don’t think it is anything to worry about yet.

But then maybe this is just something you noticed that was always there, and it is your subconscious setting you up with a reason to pre order the 5D III.

Quote:

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Originally Posted by HDNitehawk

But then maybe this is just something you noticed that was always there, and it is your subconscious setting you up with a reason to pre order the 5D III.

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:) Ha...I like it. My subconscious is very wise.....but I think it is more than that. It was a freak thunderstorm that caused me go take pictures...my subconscience couldn't cause a thunderstorm....I am thinking there are significant forces that want me to get a 5DIII.....

I get the same thing on my 7D (maybe worse). It does not seem to be dust. Mine show up red, blue, or white, and they only become obvious with long exposures or dark areas. I spent a fare amount of time cleaning them up. However, there was one big benifit that I noticed when I got Lightroom in January... I no longer have to clean them up in PP - it does it automatically. I did not know this was a feature, but when I open a picture the spots will show up at first, then as the preview is fully rendered, it disappears. I do not know what it is doing or how, but the first time I saw them disappear on the screen I was happy not to have to deal with it anymore. Has anyone else noticed this? I do not believe it is the long exposure noise reduction setting in the camera because they do not get cleaned up in DPP.

Quote:

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Originally Posted by conropl

Has anyone else noticed this?

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Yes. This has been a long-standing feature of Adobe Camera Raw (and therefore Lightroom). The downside is the same as most Adobe software: they don't give you any control over it. Other programs, like Bibble, let you disable the feature if desired, and even tune all the parameters of the algorithm for your particular camera (or shot). Adobe dumbs things down to the point of the extreme (IMHO).

Quote:

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Originally Posted by Daniel Browning

Yes. This has been a long-standing feature of Adobe Camera Raw (and therefore Lightroom). The downside is the same as most Adobe software: they don't give you any control over it. Other programs, like Bibble, let you disable the feature if desired, and even tune all the parameters of the algorithm for your particular camera (or shot). Adobe dumbs things down to the point of the extreme (IMHO).

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I usually want control as well, but I could not see any ill effect. I think it was doing less damage than what I was doing cleaning them up... so I am good. Thanks for confirming.

So that brings up another thought. I bet there are a lot of people out there with dead pixels that do not even know they have them, or they have a worse problem than they thought because Adobe is covering them up.

If you don't know or notice it, you don't really have a problem...do you?:rolleyes: At least that's how I look at it. I'd rather judge my photos for the photo instead of the technique. I could see specific photography that would lean more to the technique, but for the majority of people I think the auto-repair is a very nice feature.

If I had to worry about these things with each photo I take I wouldn't really enjoy it I think. I am already very picky and technical orientated when I sort out my photos according to people around me. I throw shots away for having a very tiny technical error (user and camera) while other people would have loved to print these shots as large as they could.