robrj
Member
Posts: 248
home town/country: Escondido, CA
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Post by robrj on Aug 15, 2016 19:32:02 GMT
I bought an Orion Skyview Pro newtonian OTA (203mm, f/4.9) back in September of 2015. I used the main parts to make a travel scope based on Gary Seronik's Outback Telescope. It worked well and compacted down enough to fit the mirrors in an overhead bin. But I didn't really use it that much and the areas I traveled to always tended to be heavy light polluted areas so things weren't that clear. Plus, on my next trip, I'm going to take the SLT tripod and my 70mm travel scope and give that a try with video astronomy. The 8" travel scope was just sitting in the back of my room disassembled. So I decided to put the Orion 8" back in the tube and try it in place of my Celestron 130SLT on the AVX mount. I ordered some tube rings, a 13" bar and a bahtinov mask. The rings and the bar should be here tomorrow. It's easy enough to take apart and put back on the travel scope should I desire to take it again. But I figure, why let an 8" telescope just sit there.
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Post by Rick in NWArk on Aug 15, 2016 20:59:22 GMT
I've been looking for a cheap dob or dob mirror to play with the idea of a video camera at prime focus. Just haven't made progress on this idea in the last 4-5 months :-(
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robrj
Member
Posts: 248
home town/country: Escondido, CA
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Post by robrj on Aug 15, 2016 21:43:29 GMT
I'd recommend the collapsible SkyWatcher dob. I have a manual 12". Because of the way the focuser adapters work, it gives you a lot of room for infocus. To use an eyepiece, you have to insert either a 2" adapter or a 1.25" adapter. They're separate adapters that are about 2-3" long. The focuser hole that the adapters go into is a 2" hole. So the 2" adapter is really a 2" extender and the 1.25" adapter is a 2" to 1.25" adapter. The ZWO camera will fit in either a 2" or 1.25" hole. As a result, I can put the camera in the focuser hole without any adapter and still achieve focus. Using the 1.25" adapter from my 130SLT (which is a short 2" to 1.25" adapter), I can bring the camera to focus with a 1.25" as well. Also, if needed the struts can be compacted for further infocus. They have a detent that is intended for binoviewers.
I can bring the ZWO ASI185MC to focus with a 0.5x focal reducer without any modification to the scope or adjustments to the struts.
The biggest problem with mine is it's a manual scope. I built a tracking platform before I got into video astronomy (TL Systems). It works okay. I can get shorter exposures with it. My M16 avatar image was taken with the dob. The other problem is the altitude bearings have too much stiction. It's difficult to make fine adjustments with them. I replaced them recently with some Teflon that I bought from McMasters. I haven't given it a go yet to see if it's better. I also added an aluminum strip to the EQ platform. Previously it was running on smoothed plywood, which is probably not the best for tracking.
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