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Old Aug 11, 2006, 11:31 PM   #1
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I just noticed that I have 2 hot green clusters of pixels on my KM 5D. It is only visible in ISO 200 and up and only in dark areas where green becomes noticeable.

Is this something that is covered under warranty? Does anyone experienced similar problem?
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Old Aug 12, 2006, 3:01 AM   #2
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Yes, such a cluster of hot pixels is not tolerable. You should not see any hot pixel in a jpeg picture produced by the camera. The situation is different if you take a raw shot, when the lense is covered by the lense cap, with, say 1/60th of a second and convert the raw file with RSE (= Rawshooter Essentials) to jpeg. Then virtually any KM 5D/7D shows some hot pixels. My KM 7D has 3 single dead pixels which can be easily removed with RSE without any damage.
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Old Aug 12, 2006, 8:13 AM   #3
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See if the camera will remap them for you.

To force the monthly remap, set your camera's date and time up to the last few minutes of the last day in the month.

Turn it off, and wait until enough time has passed for the internal clock to change months. Turn it on, wait a minute or two, take some photos, turn if off and check the photos to see if the hot pixels are gone.

Repeat if not successful. It's usually best to do this after the camera has warmed up some from use (the pixels are likely to be brighter when the CCD is warmer, so they are more likely to meet the threshold the internal remap routine is using to determine pixels that are too hot).

After a good remap, don't forget to reset your camera back to the correct date and time.


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Old Aug 12, 2006, 10:48 AM   #4
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Thank you for sugestions. I will definitely try it....
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Old Aug 12, 2006, 11:11 AM   #5
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Monthly Remapping of hot pixels is an undocumented feature of some KM camera models .

The pixels will need to be hot enough to meet a brightness threshold the routine is looking for (and yours appear to be), and be visible at typical shutter speeds and lower ISO speeds (versus slower shutter speeds where the noise reduction would pick them up, or higher ISO speeds). That's to prevent remapping of pixels that would not be hot in most photos.



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Old Aug 12, 2006, 11:12 AM   #6
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just my 'gut reaction':

remap ?!? to hide the symptoms of a defective/unreliable product (CCD) !!?

if it's a 'cluster' and the camera is new - return it !!!

i am in the process of switching back to film - digital, while very convenient, S**KS

if you get a defective roll of film you can throw it away and still have a good camera

a really good digital camera (20+meg) is WAY BEYOND my means, but a great film camera (eg. nikon F100, FM1, etc) is really affordable - shoot slide film and use a transparency scanner to 'digitalize' ?!

i just had an old roll of film developed/printed (shop used a Fuji Frontier) - the 'negs' are superb, BUT, the digital 4x6 prints are 'god awful' when viewed under a 2x glass

when film was actually printed from an enlarger i could scan in a 4x6 (using a $100 HP 4400c) and make a decent slightly cropped 8x10 on my canon s820 - now that the original print is digital - GARBAGE



SORRY - just ranting about the general level of crap we are all being subjected to in this 'modern' digital electronic age
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Old Aug 12, 2006, 11:23 AM   #7
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bernabeu wrote:
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just my 'gut reaction':

remap ?!? to hide the symptoms of a defective/unreliable product (CCD) !!?
I hate to "burst your bubble", but virtually all CCDs will have pixels that will be hot in some conditions.

The idea is to make sure there is an acceptable number of defects in the conditions you're using the sensor in (light, temperature, ISO speed, shutter speed).

For the defective photosites that are in a camera's sensor at typical conditions, the factory has already mapped them out. So, while you may think your sensor is perfect, chances are, it's not. When users of cameras that develop a bad pixel use software to update the table in EEPROM, they usually see that other pixels were also found (these are the ones that were already mapped out by the factory).

Keep in mind that you've got millions of photosites, and each one is only sensitive to one color anyway (Red, Green or Blue in most Bayer Pattern designs). So, the demosaic/interpolation algorithms are combining values from multiple photosites to store at each pixel location. When you see a cluster, it's usually caused by this process anyway (versus more than one photosite that's actually bad, as I've discovered by spending some time looking at the values stored in raw files from my KD-510z, which has a borderline bad photosite).

As a result, photosites that are not linear in their sensitivity (either too bright or too dark compared to the way they should be), don't have as much impact on a final image when they are remapped.

It's also not uncommon for a CCD to develop more bad pixels as a camera ages.

Basically,a manufacturer is keeping a bad pixel table in memory (EEPROM), and it interpolates around them during processing (taking values from adjacent pixels and replacing them).

With older camera models, when you had a bad pixel (either dead or stuck on) the manufacturer's typically ran a service program to update the bad pixel map. Most consumers thought the CCD was being replaced, when the camera's processing is just interpolating to replace the bad ones. ;-) Some models only do this with jpeg data, and some also replace data in raw files.

You can find software to update some models yourself now (for a number of consumer cameras made by Nikon, Olympus and others). You can even find software to update the bad pixel table in some DSLR models (for example, the Nikon D100). This software is not supported by the manufacturers (hackers figured out how to call the hidden routines in the cameras).

Here is one example that can work with some of the Nikon and Olympus consumer models (and I've got software to do it for the Nikon D100, too; and I know someone that has the factory service software for some Canon DSLR models).

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

With some newer cameras, the manufacturers started finding a way to let the camera do it without the need for separate service software. Olympus started it first (AFAIK), beginning with their Olympus E10 Model (this 4MP 2/3" Olympus desginedCCD was very bad for getting stuck pixels, so they came out with a firmware upgrade designed to let the user call the service routine to check for them and map them out). Many newer models from Olympus also have a menu choice to remap bad pixels (even though they're not using Olympus designed sensors anymore).

Konica-Minolta put in an Automatic routine to check for bad pixels and map them out monthly in some of their newer models. I've never seen it officially confirmed. But, more than one user has reported that it works on some of their higher end models (and you can fool the camera into running the bad pixel remap by setting the date up on the camera). Neat feature.

You can also find software designed to detect and map out bad pixels during Post Processing. Here is an example:

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

Some raw converters also have the ability to use a bad pixel map.


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Old Aug 12, 2006, 11:27 AM   #8
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Thank you Jim, I just followed your instructions and my two hot spots are gone...I tested on all ISOs ....great...

style="BACKGROUND-COLOR: #000000"Jim ...you just made my day... :-) I'm again happy owner of KM 5D.
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Old Aug 12, 2006, 11:33 AM   #9
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Steve101 wrote:
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Thank you Jim, I just followed your instructions and my two hot spots are gone...I tested on all ISOs ....great...

style="BACKGROUND-COLOR: #000000"Jim ...you just made my day... :-) I'm again happy owner of KM 5D.
No problem. I'm glad to help.

Be happy you're not using a newer camera from Nikon, Canon or Pentax. You'd need to send it in for them to remap the pixels using their service software (since I'm unaware of anyone that's figured out how to update their bad pixel map in EEPROM yet and the service software for them has not leaked out).

I do have remap software for the Nikon D100, though. lol

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Old Aug 12, 2006, 11:48 AM   #10
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bernabeu wrote:
Quote:
just my 'gut reaction':

remap ?!? to hide the symptoms of a defective/unreliable product (CCD) !!?

if it's a 'cluster' and the camera is new - return it !!!

i am in the process of switching back to film - digital, while very convenient, S**KS

if you get a defective roll of film you can throw it away and still have a good camera

a really good digital camera (20+meg) is WAY BEYOND my means, but a great film camera (eg. nikon F100, FM1, etc) is really affordable - shoot slide film and use a transparency scanner to 'digitalize' ?!

i just had an old roll of film developed/printed (shop used a Fuji Frontier) - the 'negs' are superb, BUT, the digital 4x6 prints are 'god awful' when viewed under a 2x glass

when film was actually printed from an enlarger i could scan in a 4x6 (using a $100 HP 4400c) and make a decent slightly cropped 8x10 on my canon s820 - now that the original print is digital - GARBAGE



SORRY - just ranting about the general level of crap we are all being subjected to in this 'modern' digital electronic age
Of course the digital world is not perfect...and I should now (i'm designing motherboards fo past 5 years...). But it gives us more freedom and it is convenient and as fas as quality....it is getting there...if you use RAW than it is close to film quality...

I have a friend who strictly shots on film ...using NIKONFM3A. And even hesometimes appreciatesnice shot from digital....I just want to say there is place for everyone in this world and if you not happy with something..don't do it...

Cheers,


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