Steve's Digicams Forums

Steve's Digicams Forums (
-   Panasonic / Leica (
-   -   [Recovered Thread: 37632] (

David C Oct 25, 2004 7:59 AM

1 Attachment(s)
Of concern for me at the moment is a possible defective pixel on the sensor of my new FZ20 - I've noticed that I get a small red dot in one spot of the frame if that area has low brightness. High saturation in that area is OK - but when it should be dark the pixel misfires as red quite often (see attached pic)...

I hope I don't have to send the camera back - I've only just got it after a long wait and I am otherwise happy with its overall features and performance.....

Has anyone elsecome across a problem like this?

JimBailey Oct 25, 2004 9:23 AM

No, I haven't so far, but,since the camera is new, I'd send it back for a replacement if the red pixel shows up in the same place on numerous shots. I don't shoot many nighttime or sunset shots, so I probably wouldn't even notice an errant pixel like that.

I had to send my FZ20 back for a replacement because of a defective USB cord. I could've used my card reader to upload pictures, but, when I buy a new camera, I want everything to work perfectly.

akirabbq Oct 25, 2004 9:45 AM

If the red spot appears on every single shots, then it is a dead pixel. Try to send the camera back.

If not then you can try different shutter speed and aperture. If the red dot disappeared then the red dot is only a hot pixel. Hot pixel is unpreventable on all DC/DSLR, and is caused by charge leakage and overheating of the CCD.

bobc Oct 25, 2004 10:03 AM

I have had mine for over a month and have not seen anything like that. I would definately send it back. They may even let you hold on the the one you have until you get the new one so you wont be without a camera (if you had it shipped).

akirabbq Oct 25, 2004 11:29 AM

BTW, I have had my FZ10 for over half a year and the red dots do randomly appear in some of photos but it's extremely rare, and indeed it's very hard to spot the hot pixel on the photo.

NewsyL Oct 25, 2004 12:11 PM

Hot & Dead pixels are common to all digital cameras, more so as they age.

Hot pixelstend to become more prominent in an image depending on how long the camera has been in operation due the imager chip heating up from the power flowing through it and also due ambient heat. Hot pixels will bloom a bright pink, red, blue, or green colour.

Dead pixels are simply a dark spot on the image.

Another factor influencing the visibility of Hot or Dead pixels in an image is the length of exposure.Generally, the longer the exposure thebrighter the hot pixels will be. BUT.... a lot of today's cameras have noise reduction software that becomes active if the exposure time is longer than, for example, 1 second. Typically the camera will actually take a second "closed shutter" image and use it as a baseline for the first image, subtracting from the first all the hot pixels that show up in the second. Hence, long exposures may show less hot pixels than shorter exposures.

I'm not sure, but perhaps some newer cameras may have an automapping feature where the are "mapped" out. I know several brands where you can return the camera to the repair centre and they will map out the hot and dead pixels for you. Other models you simply have to replace the imager assembly - CCD chip and all.

You can test for hot & dead pixels using a nifty piece of software called "Dead Pixel Test" here...

Note that you can adjust the parameters of this utility to catch pixels that you cannot see but may one day become obvious.

Myself, I'd really be interested to learn what Pansonics solution is for dealing with this issue. Do they remap "IN" camera, remap at the repair centre, or do they simply replace the imager assembly?

I'm seriously looking at the FZ20 but once burned twice shy. I had a terrible experience with Canon's Repair Center and my old old G1three years ago which I do not want to repeat. In a nutshell, over a 6 month period the camera went back to them 3 times and each time the imager assembly was replaced with a different (note I did not say "new") imager assembly that also suffered from several hot pixels.

Today I live with the following. This is a reverse image of a shutter cap over lense shot. Orange arrows point to pixels that show up in many images and Blue arrows are pixels that sometimes show up when the camera gets really warm such as after extended operation or in the ambient heat of the Arizona desert. I've become very proficient at removing these pixels with the clone tool in any images I desire to post online or print to a large format.

bobc Oct 25, 2004 12:45 PM


Thanks for the info. I have had my FZ20 for over a month now. I just downloaded the software and took 9 lens cap shots ranging from 1/100 to 8 seconds, and tested each shot. They all came out clean. 0 hot, 0 dead.

I will do this on a monthly basis.

Thank you...


NewsyL Oct 25, 2004 4:09 PM

None at all? I'm really surprised. Try the test again but with the thresholds more sensitive.

propwash Oct 25, 2004 8:07 PM


Thanks for the link on that test program. I tried it out on my new FZ3 and had no hot or dead pixels. I did screw up , though, and had it test a regular picture, not a TIFF image that I took with the lens cap on. It came up with some phenominal number of bad pixels, but the histogram showed a nice bell curve! I see now why they want you to test a completely black image! Thanks again for the tip.

bobc Oct 25, 2004 9:18 PM

NewsyL wrote:

None at all? I'm really surprised. Try the test again but with the thresholds more sensitive.
What settings do you recommend?


All times are GMT -5. The time now is 2:25 AM.