Monday, December 08, 2008

Nikon D-50 Cleaning Dust from Sensor

So, on some bright long-exposure shots, I noticed there were some consistent dust spots. I took some slow-shutter, out-of-focus test shots to see. I changed lenses thinking it could be one of the internal elements, but nothing---the dirt was on the sensor. I decided to clean out the inside of the body. Some dust was accumulating on the reflex mirror and the window for the viewfinder. However, if you move the mirror down and out of the way (ever so carefully!), there is a door in the rear which is called the shutter curtain. I thought I was out of luck and needed help, until (completely by chance) I came across a section in the User Manual about cleaning the low-pass filter.

You can see the dirt at about 4:30 in this test shot.

I knew that the low-pass filter was a fancy term for an IR filter that happens to provide an air-tight seal for the CCD sensor. There's a procedure in the manual that enables you to lock open the reflex mirror and the shutter curtain, exposing the low-pass filter and sensor. I highly recommend that you read these instructions; they're very easy to follow. They recommend not to contact the low-pass filter, and I totally agree.

I followed the instructions for locking the mirror and curtain open, and when I removed the body cap, I could clearly see the debris on the sensor. I simply blew some air in there, and it was freed. I recommend blowing air while holding the body upside-down. Make sure you have a lot of light.

Nikon also has directions for setting up test shots for seeing if you have a dust problem. It is geared for their dust removal software, but it also serves as a diagnostic.

Test shot following Nikon's directions after cleaning


You turn the camera off to exit the special lock mode. Presto! No more dirt on my photos!