Handbook for SXV-M5 Issue 1 June 2004
28
will be very much out of focus. However, if a powerful contrast boost of the image is
carried out, they may well begin to show as the shadow ‘Do-nuts’ mentioned earlier.
Images taken with a large F ratio optical system are more likely to be affected by such
dirt, owing to the smaller and sharper shadows that they cast. There is no great
difficulty in removing such particles on the outside surface by the careful use of a lens
cleaning cloth or ‘air duster’ and so you should have little trouble with this aspect of
maintenance. Dust on the CCD faceplate is a much greater nuisance, as it casts very
sharply defined and dark shadows and it entails dismantling the camera to get rid of
it! To clean the CCD you will need a good quality lens cloth (no silicone) or tissues
and some high-grade isopropyl alcohol. A very suitable cloth is the ‘Micro-Fibre’
type marketed by PENTAX etc., and suitable alcohol is available from TANDY
(Radio Shack) etc. as tape head cleaning fluid. A bright light and a strong
watchmakers eyeglass will also be found essential.
Procedure:
1) Disconnect the lead from the camera head and remove it from the telescope. Place
it on a table with the optical window facing downward.
2) Remove the two M3 screws from the camera back plate and ease the plate out of
the camera body. You may need to press down with a finger on the USB socket while
pulling up on the camera barrel to overcome the friction.
3) Withdraw the body cylinder and unscrew the two long spacer pillars from the heat
sink plate assembly.
4) The entire camera electronic assembly can now be lifted away from the camera
front barrel and the CCD will be readily accessible. Note that a layer of white heat-
sink compound is applied to the periphery of the heat sink disc and this should be left
undisturbed by subsequent operations.
5) You can now closely examine the CCD faceplate under the spotlight using the
watchmaker's glass when any dust motes will show clearly. If there is only an odd
particle or two and the CCD is otherwise clean, carefully brush away the dust with a
corner of your lens cloth. A smeared or very dusty CCD will need a few drops of
alcohol to clean thoroughly and you may have to make several attempts before the
surface is free of contamination. One gentle wipe from one end to the other, with no
return stroke, will be found to be the most effective action. DO NOT rub vigorously
and be very careful to avoid scratching the window.
6) Before re-assembly, make certain that the inside surface of the front window is also
clean, and then carefully replace the camera front barrel and screw it into place. (If the
heat sink seal is disturbed, renew it with fresh compound before reassembling).
7) Replace all the camera parts in reverse order and the job is done.
Dealing with condensation:
The SXV-M5 is designed to avoid condensation by minimising the volume of air
trapped within the CCD cavity. This normally works quite well, but storage of the
camera in a humid location can lead to the trapped air becoming moist by diffusion
through the optical window mounting thread etc. and result in condensation on the
CCD window. If this becomes a problem, try to store the camera in a warm, dry place,
or in a plastic lunch box containing a sachet of silica gel desiccant.
