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Old Jun 16, 2007, 11:43 AM   #11
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i had a dead pixel square in the center of my 14' plasma tv here on my desk....sharpie took care of that problem..lol
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Old Jun 16, 2007, 11:46 AM   #12
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Nah... Those aren't bright enough to worry about if that's a lens cap on test. I doubt they'd even meet most thresholds to be considered hot. lol

Chances are, you're not going to notice them in a typical shot where you've got some light hitting the photosites. ;-)

There is a test available if you're curious how many you may have at slower shutter speeds.

http://www.starzen.com/imaging/deadpixeltest.htm

You'd need to turn noise reduction off to use it (since it would map them out if it saw them on the actual exposure and the extra "dark frame" exposure it takes to compare against during long exposures).

But, it's not uncommon for many cameras to have hundreds of hot pixels on longer exposures with noise reduction turned off (especially if you've been retesting it a lot, since a warmer CCD will tend to have more). DSLR models are usually a bit better in this area, though. lol

Here's an old thread where I used that utility when someone with a new Sony was worried about it:

http://forums.steves-digicams.com/fo...mp;forum_id=28


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Old Jun 16, 2007, 11:12 PM   #13
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So there isn't a bunch of martian space ships hiding around the moon...what a relief
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Old Sep 8, 2008, 10:41 PM   #14
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To rehash an old topic with a new model, I have a new a200 (second one in a week after the first one had dust on the sensor and the store replaced it) that appears to have two hot pixels on the CCD. I have read over some on this forum about this problem and have tried the suggestion of advancing the date one month ahead, powering off, then powering on and moving the date back. While the access light did come on for about five seconds, when I turned it back on and did another lens cap picture at ISO 100, the two hot pixels remain, regardless of having the long exposure noise reduction on. Is this worth returning the camera to be replaced with a new one? Will I just annoy the store I am dealing with and get a new camera with different hot pixels? Is this just a fact of life regardless of the brand or model of camera?

I like the camera quite a bit and bought it because I am able to use my old Maxxum lenses with it. I wonder if I am being unreasonable over this.

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Old Sep 9, 2008, 7:01 AM   #15
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They are probably not considered to be hot if the auto remap doesn't get rid of them (i.e., they are not bright enough to be considered hot and wouldn't show up in images if you weren't trying to do a lens cap on exposure). Ditto for the long exposure NR (they're probably not bright enough for the brightness threshold it's going to use before it replaces them). The remap is going to look for a given brightness before they'd be considered out of tolerance for a given shutter speed. How long was the exposure?

What does Starzen's pixel test software say about it using it's default threshold settings (see my previous post with links to this free utility)?

Show us an example of what you're talking about (crop of the section with hot pixels), with the camera settings used, using something like the free Irfanview

Just open the image using File>Open, draw a box around a small section of the image with a pixel you're worried about using your mouse (click on a section of the image and hold down your left mouse button and you can make a box by moving your cursor), then release the left mouse button, use the Edit>Crop feature to crop it (so that the image size isn't too large for posts here), and save the file under a different name (File>Save As) with jpeg as the file type. You'll see a popup box with a quality slider. Set it to around 85% quality (so that the file size isn't too big), and leave the box checked to retain EXIF (so that we can see the camera settings used with an editor that can read them from the image's header).

When you make a new post, you'll see a browse button that you can use to attach the image.


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Old Sep 9, 2008, 8:51 AM   #16
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I sound like a Linux apologist. As I run Ubuntu, the best I can do for you right now is post a 80% "save quality" image. The exposure time was six seconds.
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Old Sep 9, 2008, 9:37 AM   #17
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Starzen's utility sees 10 pixels that are a bit hot:

[DeadPixelText]
Version=1.0
Description=hotpixels
FileType=JPEG
NumBadPixels=10
0=Hot,1653,491,118
1=Hot,1652,492,109
2=Hot,1653,492,129
3=Hot,1654,492,98
4=Hot,1653,493,104
5=Hot,2799,1751,94
6=Hot,2798,1752,68
7=Hot,2799,1752,130
8=Hot,2800,1752,86
9=Hot,2799,1753,84


Are you sure you have Long Exposure Noise Reduction turned on (which is not the same thing as high iso noise reduction)? That shot was at ISO 400. Does it behave the same way at lower ISO speed settings?

As for Linux, you've got plenty of options you can choose from to do something as simple as cropping. Just install digiKAm, showFoto, and the available kipi plugins and you can perform most common image editing tasks very easily. It should be in the Ubuntu repositories (although it will probably need to install some of the KDE base if you're using Gnome). You can see a list of features here:

http://www.digikam.org/?q=about/features09x

Here's your image in showFoto. I did a mouseover so you can see the crop tool in the toolbar (above the label you see for crop) that you can use for cropping after drawing a box with your mouse. You've got loads of editing features available using it.

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Old Sep 9, 2008, 11:45 AM   #18
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babo

Let us know how it behaves at a lower ISO speed setting (as those pixels may be faint enough that the camera isn't going to map them out, since they may not impact normal photos). Make sure you've got Long Exposure NR turned on, too (different than high ISO noise reduction) for mapping them out on Longer Exposures (which works differently than pixels always mapped out).

Quote:
I sound like a Linux apologist. As I run Ubuntu, the best I can do for you right now is post a 80% "save quality" image.
Digital Imaging products for Linux are coming along quite nicely now. For example, I use digiKam a lot for simple tasks (cropping, usm, refocus algorithms, resizing, curves, raw converson, etc.).

It's an easy to use free photo management solution with lots of good editing plugins available (make sure to install the latest kipi plugins, too). If you're not familiar with it, see this link for more info:

http://www.digikam.org/?q=about/features09x

Make sure to install showfoto, too (it should be in the Ubuntu repos). It's got most of the same functionality that's built into digiKam, except that it doesn't have the album related features (and you can view and edit photos without creating an album using it). I keep both installed in the Linux distros I use. See some screen captures from it here:

http://www.digikam.org/drupal/node/326

Krita is also coming along nicely, and it's well integrated into the KDE Office Suite.

http://www.koffice.org/krita/

Another product worth looking at is Lightzone (commercial, but now available for Windows, Mac and Linux operating systems):

http://www.lightcrafts.com

Pixel is also worth looking into:

http://www.kanzelsberger.com/pixel/?page_id=12

Eric Hyman also offers Bibble for multiple operating systems (Windows, Mac, Linux). It's not free, but it's super software.

http://www.bibblelabs.com/

Google's Picasa is also available for Linux (thanks to the help of the work on Wine) and it's free:

http://picasa.google.com/linux/

You can also use UFRaw (it's free and available for multiple platforms, with a plugin version available for The Gimp.

http://ufraw.sourceforge.net/

Make sure to see Raw Therapee (also available for multiple operating systems). It's not open source. But, it's very good, and it's free.

http://www.rawtherapee.com/

For imaging editing, make sure to look at Cinepaint, too (it supports 16 bit editing and more, where the Gimp is limited to 8 bit).

http://www.cinepaint.org/

Don't forget the Gimp (preinstalled in many linux distros). The development on 2.6 is coming along nicely now. So, it should be a more serious contender to commercial products supporting 16 bit editing soon, even though the current version is limited to 8 bit editing.

http://www.gimp.org/

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Old Sep 9, 2008, 7:14 PM   #19
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Jim,

Thanks for your excellent response. I was unaware of my options in Linux. If the camera mounts as mass storage, I figure success and just use The Gimp to do my processing.

I retook a lens cap last night at ISO100 with long exposure noise reduction on. I have posted that picture.

The question is, should I just take the camera back and get a new one?


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Old Sep 9, 2008, 8:14 PM   #20
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That was 25 seconds at ISO 100.

The first photo was at 6 seconds and ISO 400 (4 times the sensitivity, using a shutter speed 4 times as fast. So, that's really a "wash" between them, versus a different exposure to see if the sensor is going to perform better using less aggressive settings.. ;-)

You probably need to see how it performs at ISO 100 and 6 seconds to see how much fainter the pixels are at a lower ISO speed with the same shutter speed. ;-)

If that kind of behavior is consistent at those types of settings, and you're *sure* you have long exposure noise reduction enabled (and it may not stay set if you change modes), then I'd probably return it. If long exposure NR was not turned on in the mode you were shooting in, then I'd turn it on and see how it performs. That image looks about how it should look with NR turned off.

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