It has been some time since I last updated these pages while the stars have continued their endless circuit through the skies. My old friend Orion has arisen from his winter slumber and is moving to a good position to look at the various wonders amongst his neighbours.

The reason why there has been no updates to these pages for a while is because I’ve been completing my TAFE Certificate course and most evenings were taken up with my studies. Now that I have finished I will have more time to spend on my Astronomy
pursuits, including some astrophotography.

I thought I should add this new page to my website where I can discuss the equipment I am using and perhaps share some experiences in its use.

I am sure some of you will have stories of your own to share and I would love to hear about them from you.

Robert Smeallie

CONTACT ME

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As I have shared with you previously, I have pulled my Celestron NexStar 130 SLT telescope apart in order to measure all of its component parts and then draw it in 3D using AutoCAD.

This was not a task to be taken lightly—there were a lot of very delicate parts inside and the last thing I wanted to do was to break any of them. Fortunately all went well and the scope went back together and worked as required. I had an ulterior motive behind pulling it apart—I wanted to see how it worked, and I gained a wealth of knowledge from this endeavour. Now I know how the primary mirror is mounted on its carrier and what turning those shiny knobs on the end of the telescope does.

I also discovered that not only the Primary Mirror has alignment knobs, but the Secondary Mirror also has some hidden behind the plastic dust cap. I also found that the Secondary Mirror hadn’t been mounted to its carrier correctly. The elliptical profile of the glass was out of alignment with the elliptical profile of the carrier. Others have found this with their scopes so Celestron needs to be a bit more proactive with their Quality Control.

I also discovered that there was an appreciable gap between the outer surface of the inner tube and the inner surface of the outer housing of the focuser so that, as I turned the focuser knobs, there was quite some slop in the motion of the focuser tube. This caused the image to jump around as I moved the focuser tube in and out, ruining what I was trying to view through the eyepiece. I feel that this is one part of this particular scope that needs to be replaced by one of the better quality Crayford focusers with dual speed gearing thus providing fast zooming as well as accurate focusing on hard-to-see Deep Space objects.

Since last updating these pages I now have both a Cheshire collimator and a laser collimator, thanks to the generosity of a fellow local astronomer, Jim Murray, whom I met at the College while doing my drafting course. I discovered just how far out of collimation my instrument was and, after some diligent twiddling of the Primary and Secondary Mirror collimating screws, was able to see things much more clearly through the eyepiece. I even saw the cloud bands on Jupiter which was something I wasn’t able to do before. I still need to centre-mark the mirror so that I can do a laser collimation down the track.

I can’t thank Jim enough for his support.

I also now have a Celestron NexImage CCD digital camera which will enable me to indulge in some astro-photography. This seems to be the biggest area of growth in Amateur Astronomy, going on the content of various forums, and now I too will be dabbling in this dark science.

Thanks to the information provided by Mike Swanson on his NexStar website (http://www.nexstarsite.com) I put one Saturday to good use and successfully made a data cable to go from the telescope’s hand control computer port to my laptop. I bought a 6 metre coiled telephone handset cable which has the RJ11 connector to fit the socket in the telescope hand control. I then cut off the other RJ11 connector and had an RJ45 connector crimped on in its place by a kindly local computer wiz.

I then used an unsoldered RS232-to-RJ45 adapter from Jaycar (see image) to enable the modified telephone handset lead to connect to an RS232 port.

The latest acquisition I have made is to buy a SkyWatcher Adaptable Equatorial Mount AZ-GTi which converts my Alt-Az Computerised GoTo Mount to an Equatorial Computerised GoTo.

 

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