hot/dead pixels

Archived from groups: rec.photo.digital.slr-systems (More info?)

What is "normal" as number of hot&dead pixels of a rebel XT's sensor?
I've just noticed that I have a few in my camera and I don't know if I
should send it for repairs.

Thanks,
Ogdan

Archived from groups: rec.photo.digital.slr-systems (More info?)

bp <bp@noema.il> wrote:

> What is "normal" as number of hot&dead pixels of a rebel XT's sensor?
> I've just noticed that I have a few in my camera and I don't know if I
> should send it for repairs.

Before you do anything drastic or expensive, try the freeware
DeadPixelTest from http://www.starzen.com/imaging/utilities.htm and
read the explanation. Dead pixels are relatively rare, but hot pixels
are very common and show up primarily in longer exposures. My test found
ten hots in exposures 1/4" and slower, visible when images were viewed at
1:1 or larger.

Fortunately, my Pentax *ist-DS has an optional post-exposure processing
of long exposures to snuff out any hot pixels it finds. My 10 hot pixels
appeared only while I had that option turned off.

--
Anti-Spam address: my last name at his dot com
Charles Gillen -- Reston, Virginia, USA

Archived from groups: rec.photo.digital.slr-systems (More info?)

Hot/dead pixels are an inevitable consequence of digital imaging devices. If
you don't have any now, you will later. Manufacturers evaluate each sensor
to find hot/dead pixels at the time of manufacture and then program (re-map)
so that the camera returns an average value of the pixels surrounding each
bad one. You can do that yourself in post-processing with the clone-stamp
tool (Photoshop), but at the point when it gets to be too annoying, you can
always send the camera back to have it "re-mapped". Most camera
manufacturers will do that for free while under warranty.

HMc


"bp" <bp@noema.il> wrote in message
newsan.2005.06.05.02.06.45.330000@noema.il...
> What is "normal" as number of hot&dead pixels of a rebel XT's sensor?
> I've just noticed that I have a few in my camera and I don't know if I
> should send it for repairs.
>
> Thanks,
> Ogdan
>

Archived from groups: rec.photo.digital.slr-systems (More info?)

Howard McCollister wrote:

> You can do that yourself in post-processing with
> the clone-stamp tool (Photoshop), but at the point when it gets to be too
> annoying, you can always send the camera back to have it "re-mapped". Most
> camera manufacturers will do that for free while under warranty.
>

And some actually have a remap feature in the menu so you don't have to
send it anywhere...

--

Stacey

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Sun, 5 Jun 2005 11:39:40 +0100, "Trapezium" <nil@nil.com> wrote:

>
>"bp" <bp@noema.il> wrote in message
>newsan.2005.06.05.02.06.45.330000@noema.il...
>> What is "normal" as number of hot&dead pixels of a rebel XT's sensor?
>> I've just noticed that I have a few in my camera and I don't know if I
>> should send it for repairs.
>>
>> Thanks,
>> Ogdan
>
>
>Olympus include pixel mapping on some of their cameras - it's an even
>better feature than their self cleaning DSLR sensor, but one that gets very
>little attention.
>
>FWIW, Sigma UK told me that their SD10 also has automated pixel mapping.
>
>'Hot' pixels that appear at long exposures are common, and can't be helped -
>but 'dead' pixels that show up in the same place at all exposure/speed
>combinations are the curse of digital photography and any camera exhibiting
>such a pixel should be returned under warranty (perhaps with a note pointing
>out that if the camera had a pixel mapping facility they wouldn't be
>receiving it back!)
>
>All the manufacturers could include pixel mapping a part of the camera
>firmware - but until customers start demanding that function they won't
>bother to implement it (possibly because they make money from running the
>same sort of software fix 'off camera')
>

Lets see what Canon charges if it's out of warranty.
-Rich