Testing For Sharpness - Nokia NHL-10 Baseband Troubleshooting And Manual Tuning Manual

Hide thumbs Also See for NHL-10:

Table of Contents

CCS Technical Documentation

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.

Figure 34: Effects of dust in optical path

COMPANY CONFIDENTIAL

NHL-10

Baseband Troubleshooting

ISSUE 2 01/2004

Table of Contents