Introduction and Overview - Kenthurst Observatory

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Introduction and Overview



Welcome to the Kenthurst Observatory web site!

It is a record of my digital astroimaging efforts from 2004 to the present time.

The dome was completed in 2004 and the original imaging setup was a Meade LDX2000GPS 10" O.D. telescope with piggybacked Orion ED80 refractor. The imager was a Canon EF-S format DSLR CMOS camera with a Meade Deep Sky Imager used for autoguiding.  It is amazing how such a relatively unsophisticated , inexpensive setup could produce the images shown here. After several years of imaging it became harder and harder to do anything different and so the observatory fell into disuse.

In late 2012 a range of new astronomy products became available. These were the Software Bisque Paramount ME II computerised mount and the Santa Barbara Instruments Group STXL full -frame CCD imager with the internal guide chip in front of the filters. Shortly thereafter SBIG announced the release of the AO-X adaptive-optic image stabilizer. In the immediate years before PlaneWave Instruments had achieved great success with their range of high-quality, moderately-priced "corrected Dall-Kirkham" reflector telescopes. Canon also released an inexpensive full-frame DSLR camera the 6D.

I decided to upgrade!

An important question was the O.D. size of the primary telescope. After around 8" O.D. there is no benefit in image resolution. It is already limited by atmospheric disturbance to 1-2 arcseconds. A larger O.D. scope does give the benefit of shorter total exposure times but with a high-quality mount like the MEII this is not overly important unless one is concentrating on narrowband imaging. The MEII can track sufficiently accurately to just image over a longer total period (many stacked sub-images). Also although large scopes have faster focal ratios the field of view always diminishes as the scope O.D. size increases. Focal lengths of about 2,500 mm are, for astroimaging purposes, in my mind the "sweet spot" and allow the majority of interesting, deep-sky astronomical objects to be fitted into the field of view with little or no need to construct mosaics. I decided to purchase the Planewave 12.5 CDK. The telescope comes fitted with a precision digital microfocusser. It also has, optionally, a Delta T heater which stabilises the mirrors and serves as a dew heater. There was really only one rotator available for this, the Optec Pyxis 3" rotator, 3" being necessary to cover the full-frame Kodak 110002 CCD sensor.

For wide-field imaging of nebulae its hard to beat the Takehashi FSQ106EDXIII refractor. With a 4" O.D. and a focal length of 530 mm it fits in many reflection and emission nebulae. It also has an image circle which is large enough for a full-frame camera. I chose it as the piggybacked scope. The standard digital rotator for this scope is the Astrodon Takometer. The next decision was the digital microfocuser to use. It had to have a 3" I.D. and to not exceed the limited backfocus of the FSQ. Once again there was only one known answer, the Finger Lakes FLI-ATLAS. The Canon EOS 6D give a full-frame format and being compact does not mechanically interfere with the SBIG optical assembly on the main scope. It is not temperature cooled or temperature controlled and is the lower-resolution "single-shot". However the images it produces are very close in quality to those of the STXL.

It is interesting to compare my experiences with the original and new telescope setups. Look at the images. One can easily argue that the images taken with the original, inexpensive setup are "good enough". If cost is taken into account this is diffcult to dispute.

What then of the new setup? It is infinitely more complex that the original one and has taken a very long time to get into almost acceptable working order. The images I am getting at this point in time, March 2015, are at last better that past ones but there is still a very long way to go before I get close to the results being achieved by the best astro imagers. This is a challenge. And that's a large part of the fun.

I hope you enjoy your time on this site!

If you have any questions, or even better, suggestions please drop me an email at


Phil Montgomery

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