D90 - sensor quality/hot pixels (mode 3)

Farbror · May 27, 2010

Hi,

After reading about the algorithm used in Nikon DSLRs to remove hot pixels, I attempted to bypass it in my own Nikon D90. I enabled the long-time exposure noise reduction setting, set ISO to 3200, exposure to 30 secs and aperture to 3.5. With the cap on, this is the result (acquiring the image and bypassing the hot-pixel removal algorithm)

(slightly more than what is visible here due to resizing)

cropped:

What struck me is the large amount of "hot" pixels. I redid the test with 200 ISO:

(again slightly more than what is visible)

cropped:

Basically, I'm wondering if the amount of hot pixels I'm seeing is normal for this camera or if the sensor is crap.

Ben Seese · May 27, 2010

Absolutely normal performance. Don't worry about it at all, and out in the real world, don't use Long Exposure NR. It duplicates the hot-pixel-filter that is already applied to all exposures of 1 second & longer (besides Mode 3 shots, of course).

--
http://www.benseese.com

hoof · May 27, 2010

Looks a lot like mine.

In my case, I had a blue hot pixel right in the center of the view, usually on something I care about. At ISO 200 it's barely visible, but at ISO 3200, my target usually has a bright blue dot. Anything in the middle does this, and it's annoying.

Fortunately, I found out how to edit these out in Capture NX2, using the auto-fix brush. I shrunk it to the point where it gets rid of all trace of the pixels, but not any bigger than necessary. For .NEF files it's about 1/2 the size required for JPEG. Since Capture NX2 lets you save such edits and apply them in a batch, my process is to now save all pics in .NEF on the camera, then convert them to JPEG using Capture NX2 and the auto-fix brush in batch mode. That tool works really well, even on details.

It's annoying though, as I'd rather be able to map out those hot pixels. Plus, Capture NX2 is rather slow at batch-processing files for some reason.

capanikon · May 27, 2010

It's normal.

rfclark · May 27, 2010

I too experienced 'hot pixels'...one of them was located right in the middle of the image and most apparent if the area was low light or shadow.

This was under normal lighting conditions and not something I felt was acceptable.

If the image was shot in raw, after opening it in Adobe Camera Raw v 5.5, the pixel was no longer visible...apparently ACR found and corrected it.
JPEGs were not corrected and the pixels had to be cloned away.

I sent the camera off to Nikon's service shop (Precision Camera, Enfield, CT) and after two attempts, it was fixed.

The technicians apparently mis-read the problem description the first time around...
****
--
http://s60.photobucket.com/albums/h40/rclarkphotos/?albumview=grid

capanikon · May 27, 2010

I've yet to use a DSLR that doesn't have a hot pixel or four. Don't worry about it. Use the clone tool in Photoshop.

If it's really bothersome, switch to film. Problem solved!

CSpectre · May 28, 2010

All sensors exhibit this behaviour. Not all pixels are equal, as the manufacturing process is not perfect. It tends to be a larger issue on smaller sensors where the manufacturing tolerances are much smaller, so a slight change in pixel properties results in a large difference between pixels.

My old Fuji S9600 for example, has more hot pixels at ISO200 on a 30 sec exposure than the images here show at ISO1600. And no in camera filtering to help either.

Thomas Comerford · May 28, 2010

hoof said:
Looks a lot like mine.

In my case, I had a blue hot pixel right in the center of the view, usually on something I care about. At ISO 200 it's barely visible, but at ISO 3200, my target usually has a bright blue dot. Anything in the middle does this, and it's annoying.

Fortunately, I found out how to edit these out in Capture NX2, using the auto-fix brush. I shrunk it to the point where it gets rid of all trace of the pixels, but not any bigger than necessary. For .NEF files it's about 1/2 the size required for JPEG. Since Capture NX2 lets you save such edits and apply them in a batch, my process is to now save all pics in .NEF on the camera, then convert them to JPEG using Capture NX2 and the auto-fix brush in batch mode. That tool works really well, even on details.

It's annoying though, as I'd rather be able to map out those hot pixels. Plus, Capture NX2 is rather slow at batch-processing files for some reason.

Here's an alternative approach you can use, if you're running Windows: http://www.pixelfixer.org

--
http://www.pixelfixer.org

Search

D90 - sensor quality/hot pixels (mode 3)

Farbror

New member

Ben Seese

Senior Member

hoof

Senior Member

capanikon

Senior Member

rfclark

Leading Member

capanikon

Senior Member

CSpectre

Active member

Thomas Comerford

Veteran Member

Similar threads

Keyboard shortcuts