Tuesday, June 20, 2017

Bought an 8-inch Celestron

Earlier this month, a long term goal of mine was fulfilled. I have always wanted to be able to take photos of the moon, planets and deep sky objects, but my experience with film decades ago led me to shelve the idea, Merely focusing the camera was very difficult, and light pollution made long exposure work difficult to impossible, I also found the venture too expensive and complicated for me so for nearly three decades I stayed with visual observing. Over the years, the cost of photography capable telescopes and mounts have gone down while the capabilities have greatly increased over was what available back in the 1980's. So I spent $2,500 on a 8-inch Celestron EdgeHD SCT with an AVX mounting and accessories needed to accomplish lunar and planetary imaging as well as visual observing. I have been using it over the past few weeks to familiarize myself with the telescope and mounting. Last Sunday I decided to try video imaging of Jupiter with my 60 dollar Orion Starshoot video eyepiece.

To get the video from which I extracted this picture, I inserted the stock 1 1/4-inch prism diagonal into the visual back so I can switch between the camera and an eyepiece. Once centered in the field of a high power eyepiece, I turned up the gain all the way on the camera, then inserted it and a 2.8X Barlow lens so I could focus and record the video. Because my polar alignment was not precise, Jupiter was drifting to the south as the telescope tracked the planet. The telescope-Barlow combination resulted in an effective focal length of nearly 6,000 mm, enough to get a large enough image on the very tiny chip the Starshoot video eyepiece has.
Once I had the video, I downloaded the program Registax6, which is a free program for extracting frames from video files and stacking them to form a higher quality still image, I washed the video through this program then further processed the image with Adobe Photoshop.
Un-sharp masking and adjusting the color balance was the final touches to the results you see here. I probably created artifacts in these images by heavy use of the wavelet functions in Registax and un-sharp masking in Photoshop, but the seeing was poor and the video was blurry. I suspect the prism diagonal may have added an odd color fringing effect to the planet, which will be investigated the next time I try imaging by switching to one of my mirror star diagonals.
The combination of an 8-inch EdgeHD SCT and an AVX mounting represents an incredible value for the price. While it's not perfect by any means, it's steady, portable, and the optics compare favorably to all reflecting Newtonian telescopes of high quality. In a head to head comparison on Jupiter and Saturn at 300X, the views were very similar. Faint features were easier to see through the 10-inch, mainly due to the greater aperture. When properly aligned with regards to the celestial pole and the GOTO system, the mounting can place target after target in or very near the field of view at 300X. It does however, require care be taken to get a good alignment with the sky, a process the hand controller walks you through. The mounting is rated for loads of up to 30 lbs. not including the counterweight(s). You will need another counterweight or a heavier one if you add a camera to this telescope in order to balance it properly. The tripod is rock solid, and vibration suppression pads make it even more so. Best of all, it breaks down into sections, which are the tube, equatorial head, counterweight and tripod, none of which weigh more than 20 lbs. Set up this telescope weighs in a 55 lbs. or so. All of it easily will fit in the back seat of a car. The telescope also works well with any eyepiece of good quality. I have a range of eyepieces of various designs, and tried them all with the Celestron. While no telescope can do everything equally well, this combination of telescope and mounting come closer to that impossible dream than most. Few telescopes work very well for both visual and imaging, and the EdgeHD optical tubes, which also are made in 9 1/4, 11 and 14-inch apertures, do indeed fill both roles well. The telescope runs off of 12-volt DC power, which can be supplied by an AC adapter or a portable 12-volt power source such as the one beneath the tripod. I have yet to take it out to a darker site than my driveway, but that opportunity may come this weekend, if tropical storms and hurricanes don't intervene. Right now tropical storm Cindy is leaving my area with a sloppy, wet and windy parting kiss.
I have no intention of retiring my Dobs, but since I have many more opportunities to observe and image the moon and planets than observing deep sky objects, I'd like to make more use of those nights at home. So I will continue to observe and sketch objects and post them here. I will also be posting lunar and planetary images, as well as images of comets and deep sky objects as I can successfully take them. For those interested in the telescope I used for the images, there is a very good article and review of this telescope in the December 2014 issue of Sky & Telescope. There you can see for yourself why this telescope is very popular among local amateur astronomers I know personally and in regional clubs.

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