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07-20-2011, 09:51 AM   #1
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Should I worry about a couple dead pixels?

How much should I be worried about a 2 adjoining dead pixels? I was checking for sensor stains and I didn't find any however I did find a pair of dead pixels. Is this common? Or a sign of worse things to come?

I'll be sending my camera in for repair as the rear e-dial suddenly stopped functioning. Should I bother mentioning the dead pixels?

Thanks,

Javaslinger

07-20-2011, 09:56 AM   #2
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Just run pixel mapping and they'll be gone - you should not worry about them, they are common among all brands and that is why they include the pixel mapping feature.
07-20-2011, 10:14 AM   #3
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As pxpaulx said.

Also, dead (or stuck) pixels tend to develop over time so pixelmapping should be carried out occasionally.

Many postprocessing software packages map the dead pixels out automatically when you open the image (for example Adobe Camera Raw) - that's another way of dealing with the issue.
07-20-2011, 10:58 AM   #4
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If 1 percent of your pixels were bad, that would be 160,000 dead pixels - reason for concern

2 pixels are like 2 grains of sand on a beach. its nothing.

07-20-2011, 11:33 AM   #5
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QuoteOriginally posted by Javaslinger Quote
How much should I be worried about a 2 adjoining dead pixels? I was checking for sensor stains and I didn't find any however I did find a pair of dead pixels. Is this common? Or a sign of worse things to come?

I'll be sending my camera in for repair as the rear e-dial suddenly stopped functioning. Should I bother mentioning the dead pixels?
Nah, it's perfectly normal imo.
Apparently all sensors have dead pixels. And the ones that we do see are due to a few different things. However we have pixel mapping to calibrate the hardware and keep things under control.

Having said that, most RAW processors remove them by default, while others can be toggled on or off. (hot/dead pixel removal etc).
07-20-2011, 11:48 AM   #6
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Not well known is that pixels on camera sensors get zapped at high altitude due to gamma rays. (A Kodak engineer talked of this while comparing film to digital.) Depending on the sensor this can cause a line across the image like "scratched film." I've heard from a couple of international travellers who have had to have sensors replaced from this.
So you can risk film damage from xray screening or sensor damage from long flights. Think I'll vacation with film cameras this year!
07-20-2011, 12:39 PM   #7
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QuoteOriginally posted by TomB_tx Quote
Not well known is that pixels on camera sensors get zapped at high altitude due to gamma rays. (A Kodak engineer talked of this while comparing film to digital.) Depending on the sensor this can cause a line across the image like "scratched film." I've heard from a couple of international travellers who have had to have sensors replaced from this.
So you can risk film damage from xray screening or sensor damage from long flights. Think I'll vacation with film cameras this year!
this is not proven, next to that many everyday cameras are often used at high attitude without too much problems. I never came across such problem at all. even when being 12 hours up in the air with a camera that i used a bit to take some nice shots.
07-20-2011, 01:04 PM   #8
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QuoteOriginally posted by TomB_tx Quote
Not well known is that pixels on camera sensors get zapped at high altitude due to gamma rays. (A Kodak engineer talked of this while comparing film to digital.) Depending on the sensor this can cause a line across the image like "scratched film." I've heard from a couple of international travellers who have had to have sensors replaced from this.
So you can risk film damage from xray screening or sensor damage from long flights. Think I'll vacation with film cameras this year!
I think this is an Urban Myth, Gamma and other high energy particles are just active at sea level (or even in the centre of the Earth where particle detectors are built) as they are at altitude.

I think somebody read about high Sun Spot activity knocking out the electronics and Solar Panels on satellites (which happens very rarely) added a digital camera into the mix and got 5. Gamma rays are hitting you and your camera every day.

If Gamma Rays did damage sensors (and I don't think they do, but if they did) you would have to be very unlucky for the particle to go through your sensor from corner to corner and leave a trace, it would be more likely to go through at an angle or from front to back and knock just one pixel out. It would be far more likely to travel clean through it and not hit anything.

Chris


Last edited by ChrisJ; 07-20-2011 at 01:11 PM. Reason: Addition
07-20-2011, 01:30 PM   #9
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This was Kodak's view, but about commercial video:
‪Primer on Film and Digital Capture by Rob Hummel at Cine Gear Expo 2011‬‏ - YouTube
07-20-2011, 02:08 PM   #10
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i saw the video but it sounded so much like he wanted to talk crap on this subject.

the reason why they ship by boat is simply because it is MUCH cheaper.

Pixels die on cameras anyway, and some come to life after a while too!
07-20-2011, 02:50 PM   #11
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QuoteOriginally posted by Rin Quote
i saw the video but it sounded so much like he wanted to talk crap on this subject.

the reason why they ship by boat is simply because it is MUCH cheaper.

Pixels die on cameras anyway, and some come to life after a while too!
I did think it was curious that Kodak would say this, since they make digital sensors. May well be coincidence, but it's a Kodak sensor in the Leica M9 - and one of the Leica users forum members was compaining about finding a line defect upon using his $7,000 M9 after a 12-hr flight.

But as stated, pixels may fail for various reasons, and perhaps flying just increases the odds slightly. Could also be that the M9 doesn't map out bad pixels!
07-22-2011, 02:07 PM   #12
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QuoteOriginally posted by TomB_tx Quote
I did think it was curious that Kodak would say this, since they make digital sensors. May well be coincidence, but it's a Kodak sensor in the Leica M9 - and one of the Leica users forum members was compaining about finding a line defect upon using his $7,000 M9 after a 12-hr flight.

But as stated, pixels may fail for various reasons, and perhaps flying just increases the odds slightly. Could also be that the M9 doesn't map out bad pixels!

the M9 has a CCD sensor. the K-5 has a CMOS sensor. i reckon the speaker's concern about gamma rays was regarding CCD sensors. quick google-fu turned up that CMOS sensors are not as sensitive to gamma rays as CCD sensors.
07-29-2011, 06:33 AM   #13
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Before the idea that damaged sensors is relegated to myth, look at what NASA notes about the Nikon DSLRs that fly in space:

"The cameras that come back are evaluated for damage. Depending on the condition the camera may fly again. The space environment (both inside the vehicle and on spacewalks) is tough on the electronic cameras. The radiation damages pixels on the sensor. Sometimes the damage is so great that the camera does not fly again."

This from a PopPhoto interview:
How Does NASA Get a Nikon D2Xs DSLR Ready to Go to Space? | Popular Photography

The environment in planes is much less severe, but it appears that some risk exists. It's been noted that many cameras re-map dead pixels automatically, so most users would never know if this happens or not.
07-29-2011, 06:43 AM   #14
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QuoteOriginally posted by TomB_tx Quote
The environment in planes is much less severe, but it appears that some risk exists. It's been noted that many cameras re-map dead pixels automatically, so most users would never know if this happens or not.
Many Many risks exist outside the Ionosphere. Thats its job
I feel the comparison between commercial airline flights and space flight is like saying a VW will give you the same 'driving experience' a 911 GT3 would

From Whackipedia:
QuoteQuote:
The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km to more than 1000 km. It owes its existence primarily to ultraviolet radiation from the Sun.
The lowest part of the Earth's atmosphere, the troposphere extends from the surface to about 10 km (6 miles). Above 10 km is the stratosphere, followed by the mesosphere. In the stratosphere incoming solar radiation creates the ozone layer. At heights of above 80 km (50 miles), in the thermosphere, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The number of these free electrons is sufficient to affect radio propagation. This portion of the atmosphere is ionized and contains a plasma which is referred to as the ionosphere. In a plasma, the negative free electrons and the positive ions are attracted to each other by the electromagnetic force, but they are too energetic to stay fixed together in an electrically neutral molecule.
Ultraviolet (UV), X-Ray and shorter wavelengths of solar radiation are ionizing, since photons at these frequencies contain sufficient energy to dislodge an electron from a neutral gas atom or molecule upon absorption. In this process the light electron obtains a high velocity so that the temperature of the created electronic gas is much higher (of the order of thousand K) than the one of ions and neutrals. The reverse process to Ionization is recombination, in which a free electron is "captured" by a positive ion, occurs spontaneously. This causes the emission of a photon carrying away the energy produced upon recombination. As gas density increases at lower altitudes, the recombination process prevails, since the gas molecules and ions are closer together. The balance between these two processes determines the quantity of ionization present.
Ionization depends primarily on the Sun and its activity. The amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. Thus there is a diurnal (time of day) effect and a seasonal effect. The local winter hemisphere is tipped away from the Sun, thus there is less received solar radiation. The activity of the Sun is associated with the sunspot cycle, with more radiation occurring with more sunspots. Radiation received also varies with geographical location (polar, auroral zones, mid-latitudes, and equatorial regions). There are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as solar flares and the associated release of charged particles into the solar wind which reaches the Earth and interacts with its geomagnetic field.
Unless you're flying a U2 - OR flying over a Pole - don't even begin to compare a 35,000ft Airline Flight with a Space Flight in terms or Radiation or other exposure


Can totally respect a sensor exposed in space without protective atmospheric conditions would get 'damaged' - but thats a very very different kettle of fish to even the HIGHEST commercial airline flights...

Last edited by adr1an; 07-29-2011 at 10:20 PM.
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