Dust spots on new Nikon
QAfter unpacking my new Nikon D750 DSLR, I carefully removed the body cap and attached my Nikon 24-85mm zoom. When I processed the raw images from my first outing with this set- up via Photoshop Elements and Silver Efex Pro, I was dismayed to find numerous small dust spots. These are highlighted in this JPEG (above). I know that dust spots are hard to avoid in a DSLR, but is this phenomenon normal straight out of the box? As I have ambitions to produce large monochrome prints, do I just need to get used to a lot of spot healing? I’m not keen on sensor cleaning after only 200 exposures. Phil Davies
ANikon does employ dust reduction, including highfrequency vibration shaking of the optical low-pass filter in front of the sensor, where dust normally settles. There is a menu option to perform this manually in addition to automatic triggering. You could check that it hasn’t been disabled, but Nikon seems to acknowledge that its dust-reduction system isn’t infallible because it also offers a solution called Dust Off Ref. This takes a reference image designed to record the location of any sensor dust, which can then be used in software to clean up batches of images that have been affected by it.
As for your question about whether dust should be a problem on a new camera, the answer is ideally not, but it is widely reported and in normal use dust will be a problem sooner or later. In many DSLRs, such as those from Nikon, the low-pass filter is very close to the sensor surface so dust is more easily focused onto the sensor and, therefore, the image. Only one dust-reduction system, developed by Olympus for its cameras, seems reliably effective. Its SSWF (Supersonic Wave Filter) system doesn’t just vibrate the low-pass filter, but sends an oscillating wave through the glass that effectively flings dust off. The filter is also strategically positioned to be relatively far from the sensor, so stubborn dust will usually remain invisibly out of focus.