Cinematography, Lighting, and Composition - Frame-by-Frame Stop Motion: The Guide to Non-Traditional Animation Techniques - page 74

changes to a minimum and change only in a clean, interior room. If you
need to change lenses on location or outside, try to do it inside a car or out
of the wind to avoid windblown particles entering the camera. You can clean
the filter, but it is very delicate work. Some of the newer pro-sumer grade
cameras have ultrasonic auto-sensor-cleaning as an option. But, often,
the dirt has to be swabbed out by hand. Most dslr cameras have a sensor-
cleaning mode, which requires you to lift and hold the mirror open revealing
the low-pass filter in front of the sensor. This can be carefully cleaned with
a proper swab, like the Sensor Wand, and proper cleaning fluid, which you
can get at a photography store. Also, you can blow antistatic pressured air
on the filter to remove dirt. You might seriously consider having a reputable
camera store clean your image sensor. Cleaning it yourself can result in a
scratch on the low-pass filter, which is costly to replace.
These cameras were made for single-frame shooting and not really for
movie making or multihour use of multiframe exposures. Sensors can
overheat when they are in live view for long periods of time. So the
cameras get what I call pixel burnout (also referred to as hot pixels or stuck
pixels ). This is usually apparent when shooting into a darker compositional
field or during long exposures. When you throw the individual picture
files onto a large screen you can see bright little spots that are the burned
pixels. Blue seems to be the first color that appears in these pixels.
Eventually, you have to have your image sensor replaced, but in the
meantime, there are postproduction solutions like pixel sampling. This
basically identifies the burned out bright pixel and replaces it with the
color of the pixel next to it.
Burned pixels and dust on the sensor or low-pass filter are especially
noticeable on moving shots. They are also much more difficult to clean up
on a moving camera shot over locked-down shots. It is better to address the
issue (of potentially replacing the sensor) than trying to fix each problem in
postproduction. You should include sensor cleaning as a standard part of your
camera maintenance plan.
Fig 5.11 a shot of an open camera with the mirror and mirror lifted to expose the low-pass filter.