Handbook for the TRIUS PRO 694 Issue 19th April 2019
17
adjustment is needed. Before making any changes, you may like to see the
information at
https://www.sxccd.com/maintenance_info/Aligning_CCD.pdf
This describes a simple setup for checking the alignment and may save you a lot of
time and effort caused by aligning by experiment.
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Camera maintenance:
Very little maintenance is needed to keep the camera in excellent operating order,
however two problems, which are common to all CCD equipment, might show up on
occasion. These are dust and condensation.
Removing Dust:
1) Dust can be deposited on either the optical window (not a big problem to cure), or
on the CCD faceplate (very difficult to eliminate entirely). When small particles
collect on the window they may not be noticed at all on deep sky (small F ratio)
images, as they 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. A
light polluted sky will also make these marks much more obvious. There is no great
difficulty in removing such particles on the outside surface by the careful use of a
lens cleaning cloth, ‘lens pen’, 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 acetone or isopropyl alcohol. A very
suitable cloth is the ‘Micro-Fibre’ type marketed by PENTAX etc., and suitable alcohol
solution is available from photographic shops etc. as lens cleaning fluid. Most
pharmacist shops will have small bottles of pure acetone. A bright light and a strong
watchmakers eyeglass will also be found to be essential.
NOTE! You will lose the argon gas fill of the CCD chamber when it is opened. The
camera will operate well without the argon (replaced with dry air), but you can re-fill
the chamber by following the instructions at the end of this section.
Accessing the CCD faceplate:
1) Disconnect the leads from the camera head and remove it from the telescope.
Place it on a table with the optical window facing upward.
2) Examine the window retaining ring, which is screwed into the barrel and
compresses a nitrile rubber O ring under the window. You will see that it has two
small notches for rotating it with a suitable tool.
