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20D hot pixel - Photography

I got one white hot pixel. Should I bother to exchange it? How many people have got a perfect sensor? My last Digital Rebel (2nd one actually, the first one was exchanged for another reason and I didn't doa pixel test) had no dead/hot pixels. Thanx....

  1. #1

    Default 20D hot pixel

    I got one white hot pixel. Should I bother to exchange it? How many
    people have got a perfect sensor? My last Digital Rebel (2nd one
    actually, the first one was exchanged for another reason and I didn't
    doa pixel test) had no dead/hot pixels. Thanx.
    leo Guest

  2. #2

    Default Re: 20D hot pixel

    Depends on when you get it. If you get it with long exposures it is pretty
    much par for the course. Try turning on the special long exposure noise
    reduction in the camera and see if that helps.

    If it is regular length exposures (any thing faster than 1 second) I would
    exchange it as you shouldn't have it showing with those types of images.

    John


    "leo" <someonesomewhere.net> wrote in message
    news:cq095b02h16news1.newsguy.com...
    >I got one white hot pixel. Should I bother to exchange it? How many people
    >have got a perfect sensor? My last Digital Rebel (2nd one actually, the
    >first one was exchanged for another reason and I didn't doa pixel test) had
    >no dead/hot pixels. Thanx.

    John Doe Guest

  3. #3

    Default Re: 20D hot pixel

    John Doe wrote:
    > Depends on when you get it. If you get it with long exposures it is pretty
    > much par for the course. Try turning on the special long exposure noise
    > reduction in the camera and see if that helps.
    >
    > If it is regular length exposures (any thing faster than 1 second) I would
    > exchange it as you shouldn't have it showing with those types of images.
    >
    > John
    >
    >
    > "leo" <someonesomewhere.net> wrote in message
    > news:cq095b02h16news1.newsguy.com...
    >
    >>I got one white hot pixel. Should I bother to exchange it? How many people
    >>have got a perfect sensor? My last Digital Rebel (2nd one actually, the
    >>first one was exchanged for another reason and I didn't doa pixel test) had
    >>no dead/hot pixels. Thanx.

    it's already showing at 1/60 sec but possibly not showing in regular
    pictures but I like doing low night shooting... I'll get it replaced.
    It's from Amazon, they sent me a return shipping label, so it' kinda no
    hassle. Ther only worry is if the next one is worse than this one.
    leo Guest

  4. #4

    Default Re: 20D hot pixel

    At 1/60th of a second I would get it replaced. With long exposures you can
    expect more, just make sure to turn on the in camera long exposure noise
    reduction feature. This should help. I would also recommend something like
    NeatImage to help with any other noise problems. [url]http://www.neatimage.com[/url],
    great program.

    John


    John Doe Guest

  5. Moderated Post

    Default Re: 20D hot pixel

    Removed by Administrator
    leo Guest
    Moderated Post

  6. #6

    Default Re: 20D hot pixel

    leo wrote:
    > I got one white hot pixel. Should I bother to exchange it? How many
    > people have got a perfect sensor? My last Digital Rebel (2nd one
    > actually, the first one was exchanged for another reason and I didn't
    > doa pixel test) had no dead/hot pixels. Thanx.
    I thought there was a procedure in the 20D (most DSLR's) to map hot pixels such
    that they be interpolated out in succeeding images?

    --
    -- r.p.e.35mm user resource: [url]http://www.aliasimages.com/rpe35mmur.htm[/url]
    -- r.p.d.slr-systems: [url]http://www.aliasimages.com/rpdslrsysur.htm[/url]
    -- [SI] gallery & rulz: [url]http://www.pbase.com/shootin[/url]
    -- e-meil: there's no such thing as a FreeLunch.
    Alan Browne Guest

  7. #7

    Default Re: 20D hot pixel

    The odds I think are pretty good that the second one will be good. But, then
    one never knows for sure. With the price of the 20D and consider its useful
    it I think it is important to get one that is as close to perfect as
    possible.

    John


    John Doe Guest

  8. #8

    Default Re: 20D hot pixel

    Nope, not on the 20D and as far as I am concerned that type of feature is
    only a excuse for the manufacturer to do less quality control, testing and
    for not buying better quality sensors.

    John


    John Doe Guest

  9. #9

    Default Re: 20D hot pixel

    John Doe wrote:
    > Nope, not on the 20D and as far as I am concerned that type of feature is
    > only a excuse for the manufacturer to do less quality control, testing and
    > for not buying better quality sensors.
    It is likely that a 0 defect policy for over dead/stuck sensor pixels in over 8M
    would result in such a low yield as to make the product unafordable. I may be
    wrong, and I bet that Canon would be quite tight lipped about it in any case.

    I don't know if they have a 'dead pixel' spec for how many dead sensor pixels
    are acceptable at production. In fact, it would not surprise me at all that
    they do have a threshold and that they do detect dead pixels in the factory
    tests. In turn have them mapped in memory and use that to correct every image
    taken. If so, it's likely a very small number of dead sensors, like 10, such
    that it would never affect an image enough to be noticeable after the correction
    is applied.

    Given that these are spatially seperate R,G,B sensors, the loss of one of them
    won't affect the combined RGB pixel when it is computed, using data from the
    pixels around it in the interpolation.

    From there, recognizing that sensor sites might die a year or 5 or 10 years
    later, there should be the means to map and correct these as they occur. There
    is a procedure in some Nikons that actually "fixes" some dead sensors (getting
    them out of the 'stuck' state. If this applies to the CMOS sensors in Canon's,
    I don't know.)

    [url]http://www.imaging-resource.com/NEWS/998087928.html[/url] is Olympus' response to the
    issue.

    (Hard disks with dead sectors come to mind... in the 10 MB disk days we would
    would moan over a single dead sector in a hard drive. The cost/bit was too
    high. Of course this didn't affect the quality of a doent.)

    When film is returned it is not uncommon to have tiny scratches or bits of
    embedded dust in the emulsion. Not every frame, but 1 or 2 frames per roll.
    These are easilly corrected with ICE equipped scanners or a little handiwork in PS.

    Cheers,
    Alan

    --
    -- r.p.e.35mm user resource: [url]http://www.aliasimages.com/rpe35mmur.htm[/url]
    -- r.p.d.slr-systems: [url]http://www.aliasimages.com/rpdslrsysur.htm[/url]
    -- [SI] gallery & rulz: [url]http://www.pbase.com/shootin[/url]
    -- e-meil: there's no such thing as a FreeLunch.
    Alan Browne Guest

  10. #10

    Default Re: 20D hot pixel

    On Sun, 19 Dec 2004 16:56:54 -0500, Alan Browne
    <alan.brownefreelunchVideotron.ca> wrote:
    >John Doe wrote:
    >
    >> Nope, not on the 20D and as far as I am concerned that type of feature is
    >> only a excuse for the manufacturer to do less quality control, testing and
    >> for not buying better quality sensors.
    >
    >It is likely that a 0 defect policy for over dead/stuck sensor pixels in over 8M
    >would result in such a low yield as to make the product unafordable. I may be
    >wrong, and I bet that Canon would be quite tight lipped about it in any case.
    >
    >I don't know if they have a 'dead pixel' spec for how many dead sensor pixels
    >are acceptable at production. In fact, it would not surprise me at all that
    >they do have a threshold and that they do detect dead pixels in the factory
    >tests. In turn have them mapped in memory and use that to correct every image
    >taken. If so, it's likely a very small number of dead sensors, like 10, such
    >that it would never affect an image enough to be noticeable after the correction
    >is applied.
    >
    >Given that these are spatially seperate R,G,B sensors, the loss of one of them
    >won't affect the combined RGB pixel when it is computed, using data from the
    >pixels around it in the interpolation.
    >
    > From there, recognizing that sensor sites might die a year or 5 or 10 years
    >later, there should be the means to map and correct these as they occur. There
    >is a procedure in some Nikons that actually "fixes" some dead sensors (getting
    >them out of the 'stuck' state. If this applies to the CMOS sensors in Canon's,
    >I don't know.)
    >
    >[url]http://www.imaging-resource.com/NEWS/998087928.html[/url] is Olympus' response to the
    >issue.
    >
    >(Hard disks with dead sectors come to mind... in the 10 MB disk days we would
    >would moan over a single dead sector in a hard drive. The cost/bit was too
    >high. Of course this didn't affect the quality of a doent.)
    >
    >When film is returned it is not uncommon to have tiny scratches or bits of
    >embedded dust in the emulsion. Not every frame, but 1 or 2 frames per roll.
    >These are easilly corrected with ICE equipped scanners or a little handiwork in PS.
    >
    >Cheers,
    >Alan
    Some software offers a "dark frame" process to remove just the digital
    pixel image from the main image. This is done especially for longer
    exposures where more hot pixels might show up.
    -Rich
    RichA Guest

  11. #11

    Default Re: 20D hot pixel

    RichA wrote:
    >
    >
    > Some software offers a "dark frame" process to remove just the digital
    > pixel image from the main image. This is done especially for longer
    > exposures where more hot pixels might show up.
    > -Rich
    This was more in the vein of dead or hot pixels. IMO the OEM's should have a
    tool to map and fix. Esp. as they may increase over time.

    Cheers,
    Alan

    --
    -- r.p.e.35mm user resource: [url]http://www.aliasimages.com/rpe35mmur.htm[/url]
    -- r.p.d.slr-systems: [url]http://www.aliasimages.com/rpdslrsysur.htm[/url]
    -- [SI] gallery & rulz: [url]http://www.pbase.com/shootin[/url]
    -- e-meil: there's no such thing as a FreeLunch.
    Alan Browne Guest

  12. #12

    Default Re: 20D hot pixel

    My 20D seems OK, zero hot pixels at ISO400 and 1/30 sec.

    30 sec exposure there was one faint red spot - closer examination suggests
    it is more than one pixel, also noise cancellation did not remove it. I had
    the lens cap on, f32 set and shaded the eyepiece though I didn't use an
    eyepiece cap.

    Tentative conclusion was it was stray light - probably from the eyepeice. So
    I am not worried.

    I would be worried for a sub-second exposure though.

    Cheers


    Lester

    "John Doe" <john_doenospam.com> wrote in message
    news:Y60xd.13131$_3.146708typhoon.sonic.net...
    > At 1/60th of a second I would get it replaced. With long exposures you can
    > expect more, just make sure to turn on the in camera long exposure noise
    > reduction feature. This should help. I would also recommend something like
    > NeatImage to help with any other noise problems. [url]http://www.neatimage.com[/url],
    > great program.
    >
    > John
    >
    >

    Lester Wareham Guest

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