Dust, dead/hot pixels, or both?

Did another test on my refurb 7D....just took a 30 second exposure at 3200 ISO with the lens cap on.

The result looks like a clear night sky....stars and all!! Im not sure if every speck is a dead or hot pixel (I doubt it) or just dust. Take a look at the pic and tell me what you think (if you zoom in you get more of the dust looking specs....but even zoomed out you can see what looks like hot pixels)

is this a valid test, being at a higher ISO (3200)? Is it something to think about sending the camera back for? I know I can do a manual clean and they will probably get mapped out, but I wanted to note it BEFORE I did that to see if it might be a problem. My apologies for the image size, but the fact that they are pretty well spread around, I wanted it to be an accurate shot.

Thanks in advance.

-Chris

IMAGE LINK: http://dl.dropbox.com/​u/14958505/IMG_6463_fu​ll.jpg

Looks like hot pixels, to me. Dead pixels would be black, anyway, so you wouldn't see them in this sort of a shot I would think.

Little big, eh? :P

Anyways, it looks like quite a few hot pixels to me. but since we can only see about 1/6th of the image at any one time, I'm not sure...

What would you suggest to help make it easier to visualize? If I resize the pic to something smaller they are harder to see.

Is this even something to worry about?

Well, you'll want to resize the image posted to a maximum of 1024px on the longest side, per the forum posting rules. You can link to an external, high res version from that if you'd like.

As for something to worry about? I doubt it. I get the same sort of results if I do the same thing you describe but I've got no problems in real life shooting. I wouldn't stress about it; go shoot real pictures

I remember going to the doctor because my arm hurt when I bent it a certain way. Well, the Doc said "Don't bend it that way!".

Anyhow, these are pixels right? Can't see these under normal situations, then don't take picures with your lens cap on

Wouldn't think this is going to affect anything. And yes, I did stay at a Holliday Inn last night.

Cheers,

David

Snydremark wrote in post #12748299
Well, you'll want to resize the image posted to a maximum of 1024px on the longest side, per the forum posting rules. You can link to an external, high res version from that if you'd like.

As for something to worry about? I doubt it. I get the same sort of results if I do the same thing you describe but I've got no problems in real life shooting. I wouldn't stress about it; go shoot real pictures

Sorry about that, resized the pic thats shown here (its now hard to see anything wrong with it ), linked to full size.

I dont have any problems in real life shooting, except I found one pic with what looks like dust on the sensor vs it being a dead or hot pixel (it isnt bright, and it isnt pure black so Im figuring just dust). But thats what lead me to trying this test.

davidc502 wrote in post #12748351
I remember going to the doctor because my arm hurt when I bent it a certain way. Well, the Doc said "Don't bend it that way!".

Anyhow, these are pixels right? Can't see these under normal situations, then don't take picures with your lens cap on

Wouldn't think this is going to affect anything. And yes, I did stay at a Holliday Inn last night.

Cheers,

David

But that doesnt sound like the POTN way.....we'd first send the arm into Canon for calibration, then re-test after getting the arm back, then put the arm for sale on the classifieds forum so we could fund an upgrade to Arm Mark V.

I get these ALL THE TIME on long shutter speeds. I set the camera to Manual Clean, leave it for a couple minutes, and they go away until the next time I use a long shutter speed. I get it on really high ISO as well, but usually when I am trying to shoot something with a long shutter speed it is because it is dark....and so these things are all over the place.

There is a program you can get....I think it's called PIxelFixer. You can download it for free. Take a shot just like this one, load it into the program, it will find all the hot pixels, and then you can batch process your RAW images and it will map them out. Well, I think it clones them out. I don't shoot enough stuff at long exposure to mess around with that program, so I just clone them out myself.

chrisexv6 wrote in post #12748369
But that doesnt sound like the POTN way.....we'd first send the arm into Canon for calibration, then re-test after getting the arm back, then put the arm for sale on the classifieds forum so we could fund an upgrade to Arm Mark V.

Good one!

David

chrisexv6 wrote in post #12748359
Sorry about that, resized the pic thats shown here (its now hard to see anything wrong with it ), linked to full size.

I dont have any problems in real life shooting, except I found one pic with what looks like dust on the sensor vs it being a dead or hot pixel (it isnt bright, and it isnt pure black so Im figuring just dust). But thats what lead me to trying this test.

If you want to check for sensor dust, set your aperture as far down as it can go, f/22, f/30, whatever; then take a picture of, say, a clear blue sky. Focus doesn't matter. Then look at the image for specs like you're talking about.

Snydremark wrote in post #12749337
If you want to check for sensor dust, set your aperture as far down as it can go, f/22, f/30, whatever; then take a picture of, say, a clear blue sky. Focus doesn't matter. Then look at the image for specs like you're talking about.

Or if you're like us here and clear skies are few and far between you could also take a picture of a plain white wall. Take a few pictures actually while slightly shifting the camera a bit in between. When you load them on your computer it's very easy to see where the dust is and not just a spot on your wall by jumping through the pictures. The sensor dust stays in the same place while things on the wall will move slightly.