Please help, is this a "hot pixel"

[gramps]

I just shot a few time exposures with the 20 D and two different lenses. Every picture has the same red dot in it. I haven't been able to notice this until I did these night time exposures. It sticks out like a sore thumb. Is this what I've heard is a hot pixel and does anyone have any ideas what to do about it? It's in the circle I drew.

Thanks Much

http://img.photobucket.com/albums/v113/hwgramps/reddot.jpg

[drisley]

Yup, that is a hot pixel.
One or 2 hot pixels are normal on long exposures (longer than 1 second), and/or high ISO's.
You dont say how long that exposure is, but it looks like a bulb exposure of the night sky.
These can be cloned out in photoshop, or my favourite is the heal tool.

[gramps]

thanks for the info. it's a 20 minute exposure...........I just shot some pics inside of a white wall and can't fint the red dot in those, they were not time exposures. I take it that I should expect this and not think about sending the camera back?

[gramps]

"heal tool"????????? I give, what's that?

[drisley]

On a 20 minute exposure, if you only found that one hot pixel, that is a tremendous result.
I know that a 20 minute exposure on the 300D would yield many hot pixels, and alot of noise.
The heal tool is found in Adobe Photoshop 7 and newer.

[FlipsidE]

Yeah, I get spots like that on my DRebel even at fast shutter speeds (like 1/60). I have one red one just like yours in approximately the lower right of my pictures.

It's really annoying (esp for how much we paid for these cameras). But, I've heard it's not at all unusual. If you look at my shots at 100% zoom, they look like yours.

So far, I've been able to repair them all in Photoshop so that they are completely unnoticable. But, it's still annoying to know they are there.

I took one camera back because I had one close to dead pixel, one row of blue, and one row of red when I did the dead pixel test. That I couldn't live with. I'm not necessarily pleased that that read dot appears on every single picture I take (fast or slow shutter), but one spot is better than the three I had last camera. And, it seems as though all Canon digital cameras have the possibility of this issue. Esp with a DRebel, I count myself lucky that I only have one of these spots this time.

I would love to have a 20D, but I just can't justify the extra cost right now since I am a beginner and still have a lot to learn. Plus, I've been able to fix the dead/hot pixel on every picture that truly matters.

The DRebel is truly letting me attack an angle on photography that I've never been able to attack before. This isn't my first experience with an SLR, but it is my first experienc with a DSLR. It's nice to be able to produce pictures almost immediately after they are taken. And, I can snap away w/out worries of film costs or processing costs. Most of my photography experience has been with pocket size digital cameras or point and shoot cameras. So, seeing that I am a beginner that wants to learn using a good tool, the 20D just seems a tad out of my budget. If I find that I end up just absolutely loving this hobbie (which I really am so far), I could easily see a 20D in my near future (maybe w/in a year). Hopefully, if I decide on a 20D, my experience will be as good as yours (only one hot pixel on a 20 minute exposure).

FlipsidE

[FlipsidE]

"On a 20 minute exposure, if you only found that one hot pixel, that is a tremendous result.
I know that a 20 minute exposure on the 300D would yield many hot pixels, and alot of noise.
The heal tool is found in Adobe Photoshop 7 and newer."

- I agree 100%. I'm dead sure that my DRebel shots would look rather crazy on a 20 minute exposure.

FlipsidE

[pcasciola]

thanks for the info. it's a 20 minute exposure...........I just shot some pics inside of a white wall and can't fint the red dot in those, they were not time exposures. I take it that I should expect this and not think about sending the camera back?

You won't see a hot pixel on a picture of something white. Try the same long exposure in a dark closet, or if the camera permits, with the lens caps on.

I suspect Canon will not even consider taking the Camera back if there is one hot pixel. I remember calling about a hot pixel on a Toshiba laptop LCD (which didn't even have 1,000,000 pixels), and they said anything under 5 is considered normal, so I'm sure 1 out of 8,000,000 will be considered normal too.

[FlipsidE]

When I do a repair in photoshop, it usually requires covering a 3 to 4 pixel radius meaning that it's 8 actual pixels or less (probably 6 or so) that cause the issue. newegg.com won't take an LCD back unless it has at least 8 dead pixels. Even one of the largest LCD's they sell (23") has a max resolution of 1920x1200. That still doesn't approach the size of the pictures produced by the Dreb and above.

I'd say even 7 to 8 pixels on a Dreb and above is acceptable.

FlipsidE

[karusel]

I have one hot pixel too, really annoying. And when I say really annoying I mean, substitute the 'really' with a very very bad word of your personal preference. Yeah, and even then it doesn't even come close to how annoying I find it.

Is there a possibility to minimize this effect, like, by software to tell the camera that that specific photosite has gone bananas and it should rather take the data from one of it's neighbors?

[FlipsidE]

I have one hot pixel too, really annoying. And when I say really annoying I mean, substitute the 'really' with a very very bad word of your personal preference. Yeah, and even then it doesn't even come close to how annoying I find it.

- I absolutely feel your pain. For the most part, I'm very much a slob. I don't mind leaving things laying around the house if I think there's something more fun or important I could be doing. But, after paying $1000 for a camera, it really (substite 'really' for the same word karusel is thinking of) gets under my skin to find out that every single picture I take from now until I sell this camera (or it just dies) will have a flaw in it that I will have to go back and manually correct for pictures that really matter. When it comes to high dollar items (like $400 and above), I get VERY VERY picky. I become an anal rentative perfectionist. So, once again, I know how you are feeling.

But, all that said, I still am enjoying my camera. I really enjoy taking pictures, and I can't wait for my first real shoot coming up in a couple of months.

FlipsidE

[Jesper]

It's normal that digital cameras have a few hot pixels, which show up especially at long shutter speeds. I did a test once with my 10D - made a series of 2-minute exposures with the lens cap on at different ISO speeds. Especially at the higher ISO settings I can see about six hot pixels - some red, some green, some blue.

Instead of making one 20-minute exposure, you can also try making multiple shorter exposures and combining the images with software like Image Stacker (http://www.tawbaware.com/imgstack.htm). When you do it like that, you'll have less problems with noise and hot pixels.

[FlipsidE]

^^^^

The only problem is that my hot pixels don't seem to get any better or worse based on shutter speed, light, or aperature. I see the same hot pixels at 1/60" as I do at 6". I see the same hot pixels on a bright sunny day or on a shadow effect picture inside, in the dark, using flash bouncing.

FlipsidE

[kiwimichael]

Hi,

Instead of examining each of the 6 million pixels, there is a free program that will do this for you: http://www.starzen.com/imaging/deadpixeltest.htm

Cheers
Michael

[FlipsidE]

I actually went and got a new DRebel tonight. I guess everything is a trade off. After running the dead pixel on 1/30 exposure a few times with nothing returned, I started snapping a few shots...just to see what I'd end up with. So far, the picture is FINALLY pristinely clean. I can't seem to find any dead spot or hot-looking pixel that's repeatable (probably all of them caused by dust or the flash). It looks like I finally found a clean CMOS camera (so happy about that).

But, a clean picture comes at the price of about 4 or 5 dead pixels on the LCD. To be honest, I'm willing to live with that trade off. With all the problems I've had, dealing with a few black pixels on my LCD is something I can live with. I don't use the LCD that much anyway.

FlipsidE

[gramps]

FlipsidE I agree about the LCD tradeoff................It's good to do your menu stuff but after that.................

[FlipsidE]

All my tests were done around 1/30, so there still may be a hot pixel or two once I push the shutter speed out some. But, on my old camera, it really didn't matter what shutter speed you were running, there was always a nice noticable red dot in the same place...so far, I've probably harshly perused 10 or so pictures taken with my new camera under the same conditions, and no red dot :)

FlipsidE

[karusel]

I've got a glowing red hot pixel appearing even at 1/350s @ ISO 400. Also it is right about the center of the sensor (in the focus circle when viewed in breezebrowser). Urgh. So now, is this considered 'normal'?

[FlipsidE]

Karusel,

From what I gather from some that I've talked to, any red dots (like what I was experiencing with my last Rebel) that appear at anything less than about 1/10 shouldn't appear there. I called Canon customer service yesterday to make absolutely sure that those red dots shouldn't be there before going back for my now fifth Rebel from Best Buy. The guy on the other end of the line assured me that it shouldn't be there. I had mainly used my experiences with 1/60 indoors using a flash when discussing the issue with the customer service rep.

I had the same problem you did. I could aim the camera up at a bright blue sky (opposite direction of the sun, but with the sun still shining BRIGHTLY), and that red dot still appeared. While I didn't look at shutter speed, I would assume I was running at at least 1/250 if not 1/500 or above.

So, I took my camera back, got a new one, snapped off a few indoor shots at 1/30 and 1/60 with my flash on and took a hard look at them at 100% zoom scanning every portion of the picture with my eyes to make sure that no dot was there. This time, I think I FINALLY got a clean sensor. Unfortunately, everything comes with a trade off. I traded a clean sensor for 5 to 7 burned out pixels on my LCD. Either way, I'd MUCH prefer having a clean sensor to a clean LCD. And, after having to return my Dreb four times, I'm just sick of it all. I'll deal with the black pixels on my LCD unless they get REALLY bad. If I had any faith at all that I could return this one to BB and get another clean sensor, I would. But, after getting two cameras in a row that had issues with the sensor, i don't think I want to try anymore. Plus, I don't believe Canon would replace that 5 to 7 black pixel LCD under warranty anyway. Honestly, I'm not sure where the blame lies, but after Best Buy tried to sell me a "never opened" DRebel with a scratch on the side of the body and fingerprints all over the LCD, I would assume that it's their fault...not Canon's. But, again, either way, I'm just sick of having to deal with it. I just want to be able to enjoy shooting and know that I'll come home with pictures that don't have red dots that I have to clean up.

Honestly, when it's all said and done, we compose shots with our SLR's through the viewfinder and not through the LCD like some of the P&S cameras out there. I only use the LCD to make sure that the lighting came out the way I wanted or the picture was centered. I can still do both of those even with the burned out pixels, so I'll just deal with it.

At 1/350, though, I don't think you should see any red dots. I would contact Canon or the shop you bought it from for something like that. But, that's just me. Not sure if there was just a bad batch of Drebels at BB or those red dots are just very common on DRebs. But, either way, I would look into it.

FlipsidE

[RDKirk]

One hot pixel in a 20-minute exposure is uber doggoned good. I don't think ANY manufacturer will guarantee better than that with any camera.

Do you have Custom Function 2 turned on? That's the long exposure noise reduction. With that on, the 20D takes a second exposure immediately after the time exposure with the shutter closed, then it subtracts the hot pixels from the first exposure.