help! red dot! YIKES!

brand new 5D.. has a burning red dot on part of the image.. not the lens.. i guess it's the sensor? I see it clearly on video playback.. and it shows up briefly (same place) on stills. I say briefly because aperture 3 processes it magically away. bummer.

Return your camera and get one without this fault.

Thread closed (?)

I guess so. Just thought someone may have seen this.. kinda interested to know what it is.

I guess so. Just thought someone may have seen this.. kinda interested to know what it is.

Not heard of it before, most probably the sensor, perhaps some precessing issue, most probably not the lens.

Could you post a still from the video footage before you return the camera, be interesting to see.

brand new 5D.. has a burning red dot on part of the image.. not the lens.. i guess it's the sensor? I see it clearly on video playback.. and it shows up briefly (same place) on stills. I say briefly because aperture 3 processes it magically away. bummer.

Off hand, what you describe sounds like a hot pixel. Here how to tell: take a still image which shows the red dot, display the image on the camera's review screen, and zoom in to the red dot. Then pan around a bit. If the red dot moves, it's in the captured image. If the red dot doesn't move as you pan around the image, then the red dot is actually in your review screen.

It's a given that practically all camera sensors have either hot pixels or dead pixels. On the production line they get 'mapped out'. A neighbouring, good pixel will be "jumpered in" in place of the hot pixel. If every camera sensor had to be 100% perfect, the yield would go in the crapper and the cost of a camera would jump higher than a congressman grabbing for campaign donations.

Also: hot pixels will tend to show up at high ISOs, where the 'gain' applied to the sensor will peg a weak sensor output to one of the rails (full on or full off). Part of "high-ISO noise reduction" or "long exposure noise reduction" is a filter which detects and masks hot pixels.

Here's a clue for recognising hot pixels: There's a colour filter in front of every sensor pixel: Red, Green, or Blue. This filter is called the Bayer array, named after the Kodak whiz who came up with the classic arrangement scheme of the colour filters. See http://en.wikipedia.org/wiki/Bayer_filter for background on this. Half the pixels of the sensor have a Green colour filter, arranged in a checkerboard pattern. Half of the remaining pixels are coloured Red, and the rest are coloured Blue. So, a 24MPixel sensor will have 12M green filtered pixels, 6M red, and 6M blue. They all get upsampled from 12/6/6 to 24/24/24. This upsampling process is called "de-mosaicing". When this is being done, a single green pixel in the original 12/6/6 array will "contribute" to 4 of its immediate neighbours in the 24/24/24 output array. So a single hot pixel in the green matrix will show up in the final image as a bright green 5-pixel "star" pattern. The centre of the star will be bright (because it wasn't averaged with any of its non-hot neighbours), and the pixels immediately North, South, East, and West of the hot pixel will also be somewhat hot (well, "warm") and green. If you see this pattern, you know you've got a hot (green) pixel.

As for Red and Blue hot pixels, the de-mosaicing works a bit differently than for Green. Each Red or Blue sensor pixel from the original 12/6/6 array "contributes" (and affects) all 8 of its immediate neighbours in the 24/24/24 output array. A hot blue or red pixel will show up as a bright 3x3 pixel square, with the centre of the square being brighter than the rest.

But wait, we're not done yet.

This isn't a photography forum, this is a videography forum. You're shooting 720P and 1080P videos, not (in the case of the 5DMk2) 5616x3744 still images. There's a ton of decimation and/or binning going on to crank out "low res" 1920x1080 resolution (or lower) program material. So everything I said applies in full to the full res still images from the camera, but may have absolutely nothing to do with the camera's video output, depending on how that output format was generated.

Once again, I've told you everything I know... and more.

Hope this helps...

- Bob

it's a hot pixel, pretty common on these cams.

if you return it and get a new one, it will probably have a hot pixel or two again...

take a look at a topic I posted recently

viewtopic.php?f=14&t=12616

it's a hot pixel, pretty common on these cams.
if you return it and get a new one, it will probably have a hot pixel or two again...
take a look at a topic I posted recently
http://www.cinema5d.com/viewtopic.php?f=14&t=12616

Zvina, I'm curious. Before you sent your camera in for hot pixel mapping, did you first try enabling 'high ISO noise reduction' ? And if you did, did the setting have any effect on either still images or video?

- Bob

it's a hot pixel, pretty common on these cams.
if you return it and get a new one, it will probably have a hot pixel or two again...
take a look at a topic I posted recently
viewtopic.php?f=14&t=12616

Zvina, I'm curious. Before you sent your camera in for hot pixel mapping, did you first try enabling 'high ISO noise reduction' ? And if you did, did the setting have any effect on either still images or video?

- Bob

It worked for me... The image is now clean! Amazing!! Well I almost never go righer then ISO 800. I only see a red dot on high ISO like 1600. On ISO 3200 with "high iso noise reduction on" I see nothing, and with 6400, only a tiny gray dot! Amazing!!

Thanks bob!!

Zvina, I'm curious. Before you sent your camera in for hot pixel mapping, did you first try enabling 'high ISO noise reduction' ? And if you did, did the setting have any effect on either still images or video?

- Bob

I tried absolutely everything but nothing helped for the two bright white dots in video and high iso noise reduction did nothing for the hot pixels in stills too...

Now after remapping at the service center they're really gone....and I don't miss them a bit

.