First light with a Ioptron MiniTower
Posted 25 April 2009 - 05:02 PM
After several nights of poor weather we finally had a clear night. I was feeling real good cause I just sold the alt/az mount I had been using for several years and the MT was it's replacement. I was finally able to unpack my new MT and learn how to use it. It took me about 20 minutes by the time I got everything percolating. It took another 10 minutes to really get the hang of things and to get a reasonable alignment.
Feeling confident that I would be able to image, I slapped in my Stellacam video camera that has a maximum 8.5sec. integration time, refocused and started to image M13.
Everything so far had met my every expectation. Goto's were right in the field of view and the image when centered stayed there for a long time, the longest I stayed on a target was maybe half an hour and the image remained in the same general location.
I was using my 8"SCT at f/3.3 so mount error wouldn't be to noticeable, so I thought. Well unfortunately I started noticing that the image of M13 would slightly move a small amount and 8.5 seconds (camera integration time) later move back. This would happen on what appeared to be a random basis and the jumps would vary in length and were mostly in the vertial direction (Dec axis), but always eventually returning to the center. I tried other targets and saw the same small occasional jumps, thus ruling out scope position. I first thought it was the stepping motors, but looking at it's randomness I decided that it might be periodic error and that the quality and finish of the worm gears might be questionable. This is the first mount I've owned that exhibited this much and frequent jumps. The mount I just sold, also an alt/az used a spur gear drive and it had two small steps every 8 minutes, which was one complete gear cycle.
You might wonder why I would be using an alt/az mount in the first place and why not something more appropriate for imaging. Well that is a good question and I do have a 60 lb. GEM that works flawlessly, it has one draw back, me. I have a very bad back and also am not into piece by piece set ups. My previous mount was a NexStar and it was doing an adequate enough job but the 8"SCT with camera was pushing it and when using refractors they would hit the base of the mount. Hence the MT seemed to fit the bill, just a few pounds heavier but still manageable and I could use two scopes.
Well I don't know whether I have a defective mount or if this is typical. I'm hoping that I've over looked something. I know I've gone on, but without some explanation one wouldn't get the whole picture (and you still may not LOL). I'm into quick set ups using light equipment and small scopes and video imaging fits my make up, and that's instant imaging.
So if you have any thoughts or suggestions on what to do to remedy the jitters please pass them on.
Thanks for bearing with me,
8"SCT from 8SE
Posted 27 April 2009 - 08:26 AM
Posted 27 April 2009 - 11:38 AM
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Posted 28 April 2009 - 02:18 PM
Posted 28 April 2009 - 06:14 PM
Posted 28 April 2009 - 07:51 PM
Posted 28 April 2009 - 08:14 PM