Unwanted spots on long exposure photos

[itsummy]

Dear Friends,

I am new DSLR user, last xmas i bought a EOS 500D. First few weeks it was perfect in all exposures but recently i have noticed it has started giving few tiny bright dots (surrounded by dark circles) on long exposure photographs (more than couple of seconds). when i decrease the exposure these dots started fading. I have absolutely no idea what is causing this problem. Unfortunately i do not have another lense to try to see if it is lense issue or camera. I have fund nothin on the Internet about this. I am attaching a sample picture for your reference.

thanks for your help,
Itsummy

 

[Himanshu Gaurav]

Oh dear...that doesn't look good !!

If its always on the same spot in all pics, my guess then would be either dust on the sensor (though it appears bigger than usual dust) or more likely some condensation on the sensor that's dried now. Did u, by any chance, take out our cam to some really cold place for long and then brought it back to a rather warm room and used it again?

 

[balloonchasers]

Usual answer to your question would be that they are hot pixels from the fact that your sensor is heating up with the long exposure. But they are almost always red or blue color. Normal with long exposures.

Your image though looks more like lubricant or dried on dirt as mention above on your sensor that would show up at small f-stops. Shooting at f36 would certainly be a small f-stop! LOL Try the auto sensor cleaning function, a bulb blower, or a sensor swab if all else fails. Just google sensor cleaning and you will find a wealth of info. Cleaning your sensor is not complicated but it does take patience and common sense. Just don't use compressed air on your sensor!!!!

John
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[Btreize]

Hi, before trying any cleaning method, make sure where it is located on the sensor. Take a mag glass and put the manual cleaning on on the 500D that would reveal the sensor for you to inspect. I guess it's a moist drop as above said. in built sensor cleaning will not solve this. Your best bet is to locate it first and if blowing cleaning does not solve it then a wet cleaning should.

Good luck
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[PDine]

How long have you had this camera? When you say last xmas, do you mean the one we've just had or the one before? The reason I ask is that, personally, if the camera is still under warranty then I would send it back to Canon and let them deal with it, free of charge.

 

[KromeFoto]

Usual answer to your question would be that they are hot pixels from the fact that your sensor is heating up with the long exposure. But they are almost always red or blue color. Normal with long exposures.

Agreed. I had the same problem a few months ago and they were red in color. NR took care of some, and a few bigger ones I had to clone out.

Just don't use compressed air on your sensor!!!!

I guess the sensor will come out of the back of the camera!!! It will then be easier to clean. ;-)

John
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KF
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[Jkoether649092]

I've noticed that noise reduction can turn hot pixels into halos like that. Try taking a picture in RAW and export with no NR.
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[bakez04]

ballonchasers:

Usual answer to your question would be that they are hot pixels from the fact that your sensor is heating up with the long exposure. But they are almost always red or blue color. Normal with long exposures.

I was reading this post and was paranoid so I tried to do a long exposure test.. Are these spots what you are talking about? All spots disappear though when I use faster shutter speeds except the middle red one near the end of the wall. It is always present even at 1/8s shutter speed.. Or are they just dust,easily cleaned by a blower? Any help will be appreciated..Thank you very much..

(best viewed large)

 

[bakez04]

I was freaked out when I saw these red/blue pixels all over my pictures..

So, I've tried scouring the net and these forums for information on hot pixels. Anyway, these are information I found..

http://forums.dpreview.com/forums/read.asp?forum=1031&message=33224940

Many believe there is an undocumented feature in EOS digital cameras to map out hot pixels, and have had success with it. It's worth a try. Leave the lens on the camera and put on the lens cap. Activate the camera's Sensor Cleaning function (p. 34-35) for at least 30 seconds, then turn the camera OFF.

or check out what Ken Rockwell has to say about hot pixels..

Every camera does this. Even if it's OK today, your camera may start doing it tomorrow. Don't worry about it. If you look hard enough you'll always find them.

DON'T return a camera because of hot pixels. The replacement will, too,over time. Likewise, don't bother hand-picking a camera. I used to do this, and even the ones I picked as clean eventually picked up some hotties.

Sensors are analog, and as you analog circuit designers know, everything matters. Over time hot pixels will come and go. They won't move, but their intensity will vary.

http://www.kenrockwell.com/tech/hot-pixels/index.htm

Hope this helps out some clueless amateurs like me here..

 

[EdKiefer]

To OP : Somewhere it was posted shutter lube can be to much from factory and soon after you get spots on sensor . not 100% sure thats what you have but maybe with close inspection you can tell if something is on sensor vs hot -pixels

 

[Y0GI]

Send it in to Canon! Let them deal with it!
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When you get down to the nuts and bolts of photography, the results depend on the 'nut' behind the camera!

See the 'Plan' in my 'Profile' for my current equipment.