Canon 7D Hot pixels - Red, White and Blue?

[ankydu1]

I was recently clicking some pics with my Canon 7D and 15-85mm IS USM Lens. Upon zooming in at 100% I came across red and white dots in my image. I thought maybe the lens is dirty and reflecting some light somewhere so I cleaned it with LensPen (model: NLP-1). But the problem didn't go away. I searched google and found that repeating auto sensor cleaning a few times resolves this. Some even said to select manual cleaning and leave the lens on the camera without actual doing any manual cleaning will fix the dots. Still it didn't work. To test the camera I let the lens cap remain on the lens and clicked some pics at various ISO settings and exposure times >10 secs. I found even blue colored dots in addition to the white and red ones which is very disturbing. I have attached some pics please have a look at them and let me know if it is really a defect of the sensor. Also Once, in a room with the fan turned off and all windows closed, I removed the lens and put the cap and again did manual cleaning option. And when the mirror was locked up I opened the cap for 1-2 secs to look at the sensor and closed it. I feel the dots have increased after that, Can dust enter so quickly in the camera to cause it?

I am almost having nightmares as I spend a big chunk of my savings in getting this camera. Also Now I examined some of the older pics I took with this camera and could see the red dot now in them as well.

EXIF DATA:

dot-1, dot-2

ISO : 200
Exposure: 1/60
Aperture: f5
Focal Length f15

IMAGE: dot-1

IMAGE: dot-2

dot-3
ISO : 400
Exposure: 1.6
Aperture: f5
Focal Length 57mm
Exposure bias: +0.3

IMAGE: dot-3

ABP_1555 (TAKEN WITH CAMERA CAP ON WITHOUT THE LENS)
ISO : 6400
Exposure: 25 secs
Aperture: f0
Focal Length 50mm

IMAGE: ABP_1555







dot-4 (TAKEN WITH LENS CAP ON) Problem - white and blue dots
ISO : 1000
Exposure: 30 secs
Aperture: f3.5
Focal Length 15mm

IMAGE: dot-4

 

[ankydu1]

Someone please reply ???

 

[Joe Hanson]

Disclaimer - I am not an expert.

The last two - long exposures at high ISO - I would attribute to sensor noise.

The first two - perhaps a effect of the building light reflecting off lens elements.

The red dot on the dogs nose - ?

Did you shoot in RAW? I don't know if there's a tool that would allow you to examine the separate RGB output of the sensor, but that's what I'd try next.

 

[sweety32100]

I have 650D and it have too many hot pixels, It is not possible to take Night image with that camera...

 

[sweety32100]

+1 the image look like the camera created new planets and galaxy in the sky...

 

[ankydu1]

So is this normal to have hot pixels, are there sensors free from hot pixels?

 

[Dale Buhanan]

ankydu1 wrote:

So is this normal to have hot pixels, are there sensors free from hot pixels?

For long exposures like on the last two pictures, yes-- that is normal. All pixels have some leakage current, some have more, some have less. When the leakage is slowly able to charge the diode capacitance to the point of visibility, you can see them and they are called "hot pixels". As the camera and sensor get warmer, the leakage current increases and there are more and brighter. What you are seeing is the room temperature level but heated a bit by the sensor warming up. That is the reason that they super cool telescope sensors. It reduces the leakage current and hot pixels.

Canon has given you a way to deal with this problem. Go into your menus and make sure that high ISO noise reduction is enabled. This will do two things. It will subtract a dark frame from the shot to cancel out noise and it will apply a special high ISO noise reduction algorithm to reduce hot pixels especially. This is very helptul.

Your red-dot I don't believe is a hot pixel, it looks more like a stuck pixel, since it is there at lower ISO and faster exposures. Those you have to clone away for low light shots like you are showing. These are rarely visible in outdoor sunshine shots. Fortunately, you only have the one.

Edit: Perhaps your high ISO noise reduction is already on, and that is the reason we no longer see the red stuck pixel in the shots. The dark frame subraction would remove it.

--
kind regards
Dale

 

[ankydu1]

Dale Buhanan wrote:

ankydu1 wrote:

So is this normal to have hot pixels, are there sensors free from hot pixels?

For long exposures like on the last two pictures, yes-- that is normal. All pixels have some leakage current, some have more, some have less. When the leakage is slowly able to charge the diode capacitance to the point of visibility, you can see them and they are called "hot pixels". As the camera and sensor get warmer, the leakage current increases and there are more and brighter. What you are seeing is the room temperature level but heated a bit by the sensor warming up. That is the reason that they super cool telescope sensors. It reduces the leakage current and hot pixels.

Canon has given you a way to deal with this problem. Go into your menus and make sure that high ISO noise reduction is enabled. This will do two things. It will subtract a dark frame from the shot to cancel out noise and it will apply a special high ISO noise reduction algorithm to reduce hot pixels especially. This is very helptul.

Your red-dot I don't believe is a hot pixel, it looks more like a stuck pixel, since it is there at lower ISO and faster exposures. Those you have to clone away for low light shots like you are showing. These are rarely visible in outdoor sunshine shots. Fortunately, you only have the one.

Edit: Perhaps your high ISO noise reduction is already on, and that is the reason we no longer see the red stuck pixel in the shots. The dark frame subraction would remove it.

 

[Dale Buhanan]

ankydu1 wrote:

Dale Buhanan wrote:

ankydu1 wrote:

So is this normal to have hot pixels, are there sensors free from hot pixels?

For long exposures like on the last two pictures, yes-- that is normal. All pixels have some leakage current, some have more, some have less. When the leakage is slowly able to charge the diode capacitance to the point of visibility, you can see them and they are called "hot pixels". As the camera and sensor get warmer, the leakage current increases and there are more and brighter. What you are seeing is the room temperature level but heated a bit by the sensor warming up. That is the reason that they super cool telescope sensors. It reduces the leakage current and hot pixels.

Canon has given you a way to deal with this problem. Go into your menus and make sure that high ISO noise reduction is enabled. This will do two things. It will subtract a dark frame from the shot to cancel out noise and it will apply a special high ISO noise reduction algorithm to reduce hot pixels especially. This is very helptul.

Your red-dot I don't believe is a hot pixel, it looks more like a stuck pixel, since it is there at lower ISO and faster exposures. Those you have to clone away for low light shots like you are showing. These are rarely visible in outdoor sunshine shots. Fortunately, you only have the one.

Edit: Perhaps your high ISO noise reduction is already on, and that is the reason we no longer see the red stuck pixel in the shots. The dark frame subraction would remove it.