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Old Dec 22, 2004, 7:40 PM   #1
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I've had my 8800 for about a week now and am testing and trying all of its functions. I came across two problems(?), so far. My question is, is this typical (ie I should keep this particular camera), or is my camera defective and I should exchange it?

My LCD screen has one hot pixel in the lower left corner where the "A" typically is. The CCD imager has 4 hot pixels (lum = 80-110 from 1/30-8 sec and from iso 50-400). The four pixels from a 2x2 box and is visible as a white dot on Photoshop when blown up to about 11x14" equivalent. I have not tried printing this yet. When tested, there are still only 4 hot pixels with a lumin >15.

I own two older Olympus cameras (360 and the 730UZ) - neither has hot/dead pixels on the EVF, LCD or CCD imager. So I'm used to perfection (as least as far as hot/dead pixels!).

So, do I keep my 8800 or exchange (risk getting one worse!)? That is the question!



Bob








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Old Dec 22, 2004, 8:05 PM   #2
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I should have included this link before: http://www.starzen.com/imaging/deadpixeltest.htm

This is the software (FREE)I used to test my cameras.



Bob


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Old Dec 22, 2004, 11:52 PM   #3
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Hi. I'd exchange it as mine doesn't have that problem. It's too much to spend for that kind of irritation.

Steve
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Old Dec 29, 2004, 12:48 AM   #4
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Get it exchanged, because that's definitely defective. If you paid for the camera, then you deserve a non-defective one.
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Old Jan 12, 2005, 5:22 PM   #5
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Update - I called Amazon.com and they sent a second 8800. I ran the test on the second camera for dead/hot pixels. The second camera was also a mixed bag. It had zero hot spots (lum>60)for 1/30 and 2 sec exposures at ISO 50, 100 and 200, but over 100 hot spots (20-30 lum) at ISO 400. My first 8800 was much better (only 6)at ISO 400, but always had4 hot spots in a 2x2 block withlum=100) at all ISOs and 1/30 and 2 sec exposure. So, the second camera was noiser overall, but didn't have that ONE prominent hot spot.

I ran the test using TIF format, 8mP, NR off, and Sharp off.

Also, the second camera came with 2-3 defective LCD pixels!

So, the second camera went back and I'm considering asking for a third attempt - but I almost feel like this could be like looking for a needle (a zero hot pixel camera) in a haystack!

Bob




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Old Jan 12, 2005, 10:58 PM   #6
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Wow, Bob, talk about frustration.

Actually, someone on this forum pointed out to me that I had a dead pixel which they noted on one of my postings. I emailed Nikon and the replied that I should send it to their service center, which I did last Monday or Tuesday. Hope to get it replaced (repaired?) in short order. Now, you've got me worried.

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Old Jan 13, 2005, 7:17 AM   #7
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Bob,

Just to throw another unbiased brand-neutral opinion into the conversation.....I returned an 8800 and it had hot pixels too.

Perhaps there is a QC problem in NikonLand? Having said that, I own a D70 and 4500and they are fine so maybe it's only certain models or certain batches

Steve C.
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Old Jan 13, 2005, 9:18 AM   #8
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bob_ledyard wrote:
Quote:
I ran the test using TIF format, 8mP, NR off, and Sharp off.
Bob:

This is normal behavior (hot pixels on long exposures with noise reduction off).

You just don't see them because of the way dark frame noise reduction works (and many models engage it automatically, versus letting you choose whether or not to enable it).

If I had a prosumercamera with no hot pixels on a 2 second exposure at ISO 50 through 200 with noise reduction turned off,I'd consider myself VERY lucky.

Dark Frame Subtraction Noise Reductiontakes two photos (one of your subject, and another with the shutter closed).

Then, it looks for hot pixels in the dark frame exposure, and maps them out in the actual exposure (by interpolating values from adjacent pixels to replace the pixels thatare hot). It knows where to find them, since two exposures of the same length, taken about about the same time, usually have hot pixels in the same locations.

But, the longer the exposure, the less accurate the results. Although hot pixels usually show up at the same place in both exposures (since the temperature of the CCD is likely to be close, and the exposure times the cameras uses for both frames is the same), on longer exposures, sometimes you have pixels that are hot in the dark frame, but not in the actual frame, and vice-versa. CCD Temperature also plays a big role on how many hot pixels show up -- with warmer temperatures resulting in more hot pixels.

Up until the last few years, many digital cameras did not have a built in dark frame subtraction system. So, you had to do it yourself (take a photo of the subject, then takeanother exposure with the lens cap on using the same settings). Then, you used software to map out the hot pixels by comparing the two frames. Some utilities have the ability to compare an actual frame with a dark frame and perform the subtraction process for you. Here is a utility that can detect and map out hot pixels, with or without a dark frame:

http://www.tawbaware.com/pixelzap.htm

Because of the large number of hot pixels a camera will have at longer exposures, combined with the way dark frame subtraction works,manufacturers don'tusually consider a CCD to be defective, unless you have hot pixels on typical exposures (1/30 second or faster). Then, these pixels are known as "stuck" (always hot, regardless of exposure times).

Most CCD imagers also have stuck or dead pixels. But, what happens is that a camerakeepsa list of bad pixels in EEPROM. Then, the camera replaces them with values from adjacent pixels, so that you don't see them in yourimages. This mapping of bad pixels is done at the factory, but more can show up later.

When you send a camera in for service, they usually runa utility to identify the bad pixels, and add them to an internal table (versus replacing the CCD).Some models have the ability to perform a user remap of bad pixels (for example, some Olympus and Konica-Minolta models now have this ability).

The Sony 8MP 2/3" CCD (as used in the Konica-Minolta A2, A200; Olympus C-8080WZ; Nikon CP 8800; Sony DSC-F828; Canon Pro 1) does seem to have a relatively highnumber of hot pixels with noise reduction turned off.

Even the less dense Sony 5MP 2/3" CCD has hot pixels on longer exposures. I can remember seeing a lot of KM A1 users testing for them with noise reduction turned off when it was first introduced. ALL of the cameras tested had at least 1 hot pixel on a 1 second exposure, with hundreds of hot pixels common by the time exposures got to around 8 seconds. That's why they have Dark Frame Subtraction built in (to map them out on longer exposures).

If your camera does not have hot pixels in typical conditions (1/30 second or faster shutter speeds in normal lighting), then it's good.

As for the bad pixels in the LCD -- that's a bummer. Some manufacturers won't replace a camera for 2 or 3 bad LCD pixels, some will. For example, Konica even had anote in the user manualthat bad pixels are normal in the LCD on their KD series models.

If you like the camera, I'd get another one -- making sure that you understand that you're not going to get one with no hot pixels on longer exposures with noise reduction turned off.

BTW, I don't know if it would work on the 8800, but if you ever have a dead/stuck pixel (one that's bad, regardless of exposure settings), there is a Russian Utility designed to map them out (in the same way that a manufacturer would map them out). I don't know of anyone that's tried it with the 8800 yet though:

http://e2500.narod.ru/ccd_defect_e.htm

Basically, it sounds like the only problem you had with your second camera was bad pixels in the LCD. I wouldn't even consider pixels to be hot, unless their luminous value was greater than 60, and hot pixels on longer exposures with noise reduction turned off is normal. Even with noise reduction turned on, the longer the exposure, the less likely it will find and map all of them out, because of the way noise reduction works.

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Old Jan 13, 2005, 9:53 AM   #9
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Thank you for your explanation on hot pixels - a very good perspective!

My first 8800 had 4 hot pixels with lum from 80-110 at shutter speeds up to 1/1500 sec at all ISOs; and had 1 hot pixel each on the LCD and EVF. The LCD/EVF hot pixels were in 'camera info text areas' and thus I didn't find them objectionable. A white dot in all of my 11x14s was something I didn't want to have touse the healling brush or clone toolon for every photo.

I guess I was turned off when the second 8800 arrived with three LCD hot pixels - two of which were in the middle of the screen. I never looked at the EVF. The CCD on the second 8800 had more hot pixels but all were at a much lower lum.

For me, it may be a case of 'customer expectations'. Nikon to me was always a 'top quality' brand and when I bought their flagship prosumer digicam for $1000 I was really expecting quality - defective (to me) LCD/EVFs and a hot pixel took away from total quality. Not to start a 'brand war here', but I've either owned or bought as gifts8 other digicams from $125-500, and none of them had a hot LCD/EVF pixel.

Amazon is supposed to send a third 8800 - so my plan is to keep the better of the two and live with it! I really do like the overall capabilitiesof the 8800, so I'm avoiding going to brand xxxx! I wish that Nikon had either built-in or provided software to owners for pixel remapping. One of my other digicams has pixel remapping built-in - nice! That would save the consumer AND Nikon many headaches! I'm going to keep an eye out for success stories on the remapping link you provided.

Thanks again,

Bob




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Old Jan 13, 2005, 5:19 PM   #10
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JimC

I, too, greatly appreciated your detailed explanation of dead and stuck pixels. My one stuck pixel showed up in all pictures regardless of exposure. Having sent my 8800 back to Nikon I'm now wondering if the will do a "fix" or some kind of replacement.

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