Handbook for the TRIUS PRO-694C Issue 1 September 2020
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After conversion and the application of an ‘Unsharp mask’
In general terms, the larger the image and the worse the seeing, then the wider the
radius for best results. My Jupiter shots are usually about one third the height of the
CCD frame and I find that the ‘radius 5, power 5’ values are good for most average
seeing conditions. If you have exceptionally good conditions, then a reduction to
R=3, P=3 will probably give a more natural look to the image, as too large a radius
and power tends to outline edges with dark or bright borders.
As a finishing touch, the application of a Median filter or a Weighted Mean Low Pass
filter can be useful to smooth out the high frequency noise after a strong Unsharp
Mask.
As with deep-sky images, it is advantageous to sum planetary images together to
improve the signal to noise ratio. In this case, the ‘averaging’ option should always
be used, or the result is likely to exceed the dynamic range of the software and
saturate the highlights. Aligning the images is always something of a problem, as
there are rarely any stars to use when imaging the planets, but Jupiter’s satellites
can be useful reference points. Otherwise, you will have to find a well-defined
feature on the planet, or estimate where the centre of the disk is located. Some
more sophisticated software can automatically align planetary images and you may
find these programs (e.g. ‘Registax’) to be very useful.
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Other features of the TRIUS PRO-694C hardware and software
‘Slew & Sum’ imaging:
The TRIUS PRO-694C can be used in an automatic image-stacking mode, called
‘Slew & Sum’. The camera is set to take several sequential exposures, which are
automatically ‘slewed’ into alignment and then summed together by the software.
This mode can help to overcome a poor RA drive by summing images that have
