NHL-10
CCS Technical Documentation
Baseband Troubleshooting
40
COMPANY CONFIDENTIAL
ISSUE 2 01/2004
Copyright © 2003 Nokia. All Rights Reserved.
Figure 34: Effects of dust in optical path
If large dust particles get trapped on top of the lens surface in the cavity between the camera
window and lens, they will cause image blurring and poor contrast (see also item ‘sharpness’).
The seal between the window and lens should prevent any particles from getting into the cavity
after manufacturing phase.
If dust particles are found on the sensor or are suspected to be inside the camera module, this
is classified as a manufacturing error of the module and thus the camera should be replaced.
The particles inside the cavity between window and lens have most probably been trapped
there in assembly phase in Nokia factory. It is of course also possible that the user has disas-
sembled the device and caused the problem. However, in most cases it should be possible to
remove the particle(s) by using compressed air. Never wipe the lens surface before trying com-
pressed air; the possibility of damaging the lens is substantial.
Always check the image sharpness after removing dust.
Testing for sharpness
If pictures taken with some device are claimed to be blurry, there are four possible sources for
the clam:
1 The user has tried to take pictures in too dark conditions and images are blurred
due to handshake or movement. This is no cause to replace the camera module.
2 There is dirt between the back window and camera lens.
The back window is defective (somehow passed through window manufacturer’s
inspection). The window should be changed.
3 The back window is visibly scratched, broken or dirty.
4 Camera lens is misfocused.
Quantitative analysis of sharpness is very difficult to conduct in other than optics laboratory en-
vironment. Thus subjective analysis should be used.
