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Old Apr 30, 2006, 12:37 AM   #1
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What would you say is an acceptable number of hot pixels for a new D50? My new one has 6 hot pixels. Which of course can develop into dead pixel or stuck pixel. My last digicam I had was a Canon A75 which had no hot/dead/stuck pixels new but later developed ONE stuck pixel.

The A75is only 3mp camera with tiny sensor and D50 has a huge sensor compared to A75, which means more chance for a pixel tofail. How many hot/stuck/dead pixels did you have on your D50 (or D70) ?




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Old Apr 30, 2006, 4:34 AM   #2
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I'd say zero was an acceptable number on the sensor. I have none on my D70.



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Old Apr 30, 2006, 11:51 AM   #3
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I tried looking for any on my D50 and can't find any. Wouldn't the sensor compensate and clone the nearby pixels to fix this?

I know this is a big problem with LCDs, and in those manufacturers claim it's normal. This is one reason I don't own LCDs.
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Old Apr 30, 2006, 8:51 PM   #4
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globeguy wrote:
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What would you say is an acceptable number of hot pixels for a new D50? My new one has 6 hot pixels.


How are you testing it?

Most digital cameras are going to have hot pixels on longer exposures, depending on the length of the exposure, ISO speed, and temperature of the camera.

At typical shutter speeds (for example 1/15 second or faster), you shouldn't have any.

But, if you're trying to test it with the lens cap on with longer exposures, sure, you may get some hot pixels. I prefer to use my camera with the lens cap removed. ;-)

Make sure you've got noise reduction turned on and it will try to map them out on longer exposures (it takes a second "dark frame" image using the same shutter speed to locate them, then maps them out of the actual exposure, based on where it found hot pixels in the dark frame exposure).

This kind of system is relatively effective (up to a point), since the dark frame photo is taken immediately after the actual photo using the same settings, with the CCD at the same temperature. So, the hot pixels in the dark frame image can be used as a reference to find the ones in the actual image you took (they'll most likely be in the same spot).

Many non-DSLR models automatically engage a dark frame noise reduction system on longer exposures (usually anything over about 1 second). With most DSLR models, you can turn the dark frame noise reduction on or off as desired (so that your exposure time doesn't double on longer exposures if you don't want the noise reduction to kick in).

If you're getting hot pixelswith typical shutter speedsyou'd usemore often (versus longer exposures where the built in dark frame noise reduction would be needed to handle them), then I'd see about getting it serviced (or getting your vendor to swap out the camera if it's new.

Nikon can map them out using software (updating a bad pixel map in the camera so that it knows their location and interpolates values from adjacent pixels to replace them).

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Old Apr 30, 2006, 10:37 PM   #5
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I am using ISO1600 for 1sec exposure. Iwas not shooting a complete dark screen, rather objects in a dark room when I noticed this issue( I was not trying to look for hot pixels when I took this photo). After I took it, I noticed 6 hot pixels which were in various location with various colors.

JimC wrote:
Quote:
globeguy wrote:
Quote:
What would you say is an acceptable number of hot pixels for a new D50? My new one has 6 hot pixels.


How are you testing it?

Most digital cameras are going to have hot pixels on longer exposures, depending on the length of the exposure, ISO speed, and temperature of the camera.

At typical shutter speeds (for example 1/15 second or faster), you shouldn't have any.

But, if you're trying to test it with the lens cap on with longer exposures, sure, you may get some hot pixels. I prefer to use my camera with the lens cap removed. ;-)

Make sure you've got noise reduction turned on and it will try to map them out on longer exposures (it takes a second "dark frame" image using the same shutter speed to locate them, then maps them out of the actual exposure, based on where it found hot pixels in the dark frame exposure).

This kind of system is relatively effective (up to a point), since the dark frame photo is taken immediately after the actual photo using the same settings, with the CCD at the same temperature. So, the hot pixels in the dark frame image can be used as a reference to find the ones in the actual image you took (they'll most likely be in the same spot).

Many non-DSLR models automatically engage a dark frame noise reduction system on longer exposures (usually anything over about 1 second). With most DSLR models, you can turn the dark frame noise reduction on or off as desired (so that your exposure time doesn't double on longer exposures if you don't want the noise reduction to kick in).

If you're getting hot pixelswith typical shutter speedsyou'd usemore often (versus longer exposures where the built in dark frame noise reduction would be needed to handle them), then I'd see about getting it serviced (or getting your vendor to swap out the camera if it's new.

Nikon can map them out using software (updating a bad pixel map in the camera so that it knows their location and interpolates values from adjacent pixels to replace them).
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Old Apr 30, 2006, 11:05 PM   #6
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That would be a tough call (hot pixels with a 1 second exposure at ISO 1600).

That's on the borderline of what they may consider to need remapping.Not many people are going to try to take 1 second exposures at ISO 1600 (because lower ISO speeds would be cleaner, and 1 second is too long for a non-stationary subject anyway).

You'd be better off using a lower ISO speed with a longer exposure (you'd need a tripod at 1 second anyway, so your might as well go with a cleaner image by using lower ISO speeds, even if it means a longer exposure).

If it bugs you, see if your dealer will swap it out for another camera. You might get one that's better.
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Old May 1, 2006, 10:15 PM   #7
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maybe someone here can test their D50 using ISO 1600 @ 1sec to put his mind at ease? I would but I don't own one yet
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Old May 1, 2006, 11:37 PM   #8
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Here are some shots I just took using ISO 1600 @1 sec exposure. I can't see any hot pixels. The third one is almost-pitch black garage shot, not lens cap.











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