On Monday, October 24th in the evening…the skies above West Michigan became awashed in reds, greens, and pinks of the Northern Lights. It was such a rare and vivid display for this latitude that I rushed out to capture it at a local park with my trusty Nikon DSLR and tripod.
Here is a link to my Gallery of pictures from that night: Click here
After having to do precise polar alignment each night with my Celestron CGEM mount, it quickly began apparent that the azimuth adjustment was difficult. The problem is that to adjust it the bolt underneath had to be lose to allow movement. Even while lose, the surface friction between the tripod head and the mount head was great. This is a result the two parts being cast verse precision machined. Even with loosing the bolt up, after tightening the bolt the aligmnent shifted some, resulting in having to factor that movement in.
After many months of dealing with this reality, I came across a post on the CloudyNights mount forum about a product called Slick Strips. The idea was similar to old method of putting a CD or teflon between two mating surfaces to reduce the friction and allow from a smooth movement. Slick Strips is suppose to be the ultimate in low-friction material that is low cost(i am sure NASA has something better) Based off this post, I found where to order some Slick Strips ( ePlastics.com here ) I ordered a .030″ x 12″ x 12″ piece (Qty:1 via link given) This in theory would allow me to do this 4 times with the CGEM.
As seen below, I created a ring of the material. To do this I measures the inner/outer diameter of the tripod contact surface. Next I used a compass to trace the diameters onto the Slick Strip. Finally, I used a pair of scissors to cut the ring out. Since the material has an adhesive back, I removed the paper, positioned the ring and pressed firm to affix it to the tripod head. Super simple!
Fig A: Showing the tripod head as recieved from Celestron. The outer ring is only contact surface with the mount head.
Fig A: Original Tripod Head
Fig B: Slick Strip installed
Fig B: Slick Strip material installed
Results are very impressive, I now can have the bolt fully tightened and be able to make precise, smooth azimuth adjustments! Any questions or comments, feel free to contact me at pmumbower@gmail.com
Dew is the nemesis of the amateur astronomer using most types of telescopes. For years I have used Schmidt-Cassegrains and used a combination of dew shields and heat ropes to keep the corrector plate dew/frost free. Fast forward to the present and I now use a reflector telescope. Normally these instruments do suffer from these issues, but when they do most of the time it is the secondary mirror. That is where I was having dew/frost issues, the secondary mirror. Cutting short or affecting my astrophotography…something had to be done.
Doing my research, I quickly decided on using the dew system from Astrosystems, the “DewGuard”. This product is a circuit board that attaches to the back of the secondary mirror via silicon (i used a product from the All-Glass Aquarium company). The actual contact points are resistors, four of them for my model (DG-1) There is also a temperture sensor that contacts the mirror and measures it temperature. There is another temprature probe that measures the outside air. When the temperature difference between the two sensors is less than or equal to the preset value, the circuit activates the resistors warming the mirror. The result is dew/frost free mirror that does not distort because of too much heat being applied.
Fig A, shows the circuit attached to the unmounted secondary mirror. The arrow is to show which way the front of OTA is. Here you can also see the temperature sensor and power connector (9-volt type)
Fig A: DG-1 attached to secondary mirror back
Fig B, shows looking into the front of the OTA, the power cables are taped to the secondary spider vane along the edge to avoid altering the diffraction spike.
Fig B: LED on left, sensor on right, power wires on right vane
Fig C, show a closeup of the secondary. Here you can clearly see the LED, temperature sensor and the power wires running onto the vane. The LED has two modes: dim and “bright”. When it is bright, it is applying power to heat the secondary. It remains seen if this LED will show up in images. If so, it will be taken care of.
Fig C: close showing LED(top), sensor(bottom left), wiring (bottom)
Fig D, shows the interior of the DIY power box I had to create to get power to the Dewguard. It works on 9v-18v DC and draws .2A @ 12VDC. I had a wall wart from something laying around that put out 13.2 volts @ .75A, but I needed an interface to go from that to the 9v connector seen in Fig A.
Fig D: Interior of DIY powerbox
Fig E, show the finished project. The switch is simple SPST rocker-type to turn the power on/off. The plan currently is to apply Velcro to the back of the box and to the OTA for attaching it.
Fig E: Finished DIY powerbox
At this time (2/4/2011) I have yet to try this outside and will report back here as to the results. Any questions, feel free to contact me via email pmumbower@gmail.com
Realizing I do not have the time to “create” a website, my best option was to make use of WordPress to re-create my site. This “theme” caught my eye, at least until another one does. Until then, I am going to make every attempt to add content and make it visitable.