FZ20 - hot pixel after two years use

Related pages: Camera Panasonic FZ20 (swedish) , hot pixel evaluation

This is an attachment I sent when sending the camera to the service center for the second time. It seemed like my first error description didn't exactly match what the store sent to the service centre. And what the service centre got seemed to be different to both mine and the stores error descriptions. Anyway, I didn't have to pay anything for the round trip for the camera, but it's annoying to be without a camera for such a long time. Below is my attachment when I sent it in the second time. It's probably covered by the manufacturer warranty, I think it's two years for that kind of error (Swedish warranties rules). Otherwise, I got an even more extensive extra insurance for that camera which would cover all repair costs for it.

Error description for DMC-FZ20:

Hot pixel in sensor

This camera has started to produce an always red pixel, which by the cameras internal processing is smeared out to a larger red blob. The position of the centre of the blob is approximately (x,y)=(822,1680) for images taken at maximum resolution

Reproduction:

This is the steps which for me most often leaves the hot pixel visible.

1) Set all internal camera processing to LOW (contrast, sharpness, saturation, noise reduction)
2) Set file format to jpeg
3) Put the lens cap on.
4) Switch camera to manual mode.
5) Set exposure to F/5.6, 1/100.
6) Take picture.

Here are the results. First image is a 100% crop, second a 800% crop
ISO 80
ISO100
ISO200
ISO400

If all camera parameters is set to STD (standard) instead of low it gets even worse:
ISO80
ISO100
ISO200
ISO400

Occurrence:

The red dot seems to occur always in manual mode (manual shutter & aperture), especially at higher shutter speeds. Going down to 1/50 or lower in shutter speeds seems to sometimes remove the dot in ISO200 and ISO400 shots.

In other modes (P, A, S), I won't know in advance when the dot is going to appear or not. It seems to work fine sometimes, and it goes wrong sometimes. It's obvious that the faulty region won't be visible when nearby pixels has high values in the red channel, independently of the green and blue channel. My guess is that the venus engine (internal camera post-processing) somehow tries to determine what is contained in different regions of the image, and adapts its image filtering differently for each exposure. Automatic dark frame subtraction might correct the problem, but it won't help in normal circumstances.

Severity:

My camera and PP (post processing) habits includes occasionally printing images up to 30x45 cm (12x18"), but most prints are 10x15 cm (6x4") or 20x30 cm (12x8"). For web publishing, I mostly use 1024x768 pixel as resolution, which in certain cases means using 100% crops from the images in the camera. I usually lets the camera decide ISO when outdoors in bright light (and then it chooses between ISO80 and 150), but quite often has to force it to ISO100 or ISO200 when I don't photograph static scenes and the light is less then optimal.

Whenever I photograph static scenes which I know jpeg is going to destroy (such as blue skies), I sometimes saves the images as tiff's, as that even at only 24 bpp makes an improvement in image quality.

Anyway, the dot will show up on prints larger then 10x15 cm, and it will show up on images I publish on the web, and I have to manually alter those images to clone out the red dot when it occurs. That's not something I'm supposed to have to do to every image I take. I really depend on high quality output from the camera, both in jpeg and in tiff, most probably requiring a replacement of the faulty sensor.

Last repair

This camera was sent in a couple of weeks ago, and I got it back last Friday, without any repairs carried out, probably because the error description was fussy.

When I handed it in, I said it had a hot pixel in the sensor, and explained it for the guy at EL-Giganten who sent it in for repair. On that receipt from EL-Giganten , he had written something kind of like "red dot in every pixel in manual mode", but it seems like someone changed it to "defect" along the way before it got to your service centre in Denmark. Anyway, as it was still broken they didn't charge me for the round-trip.