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Everything posted by wrvond

  1. Diameter of Primary Mirror: 127mm Telescope Focal Length: 1500mm (f/11.8) Your telescope, at f/11.8 would be considered a slow scope. A telescope with the same aperture (127mm) but a shorter focal length - say 600mm - would be an f/4.7. That would be a "fast" scope. In this example, where the only change is the focal length of the scope, using the same eyepiece, the faster scope will provide a much wider field of view and a much smaller exit pupil. The magnification of the image will also be greater in the faster scope. So what's the advantage of your slower scope? It is mu
  2. Easy is rarely completely effective. The best way is to disassemble, thoroughly clean then lubricate with super lube, or equivalent synthetic grease with PTFE.
  3. There are creative things you can do in-camera with film that you can't do in-camera with digital. The main one that comes to my mind is the thing I missed most of all when digital cameras first hit the consumer market - the ability to make multiple exposures on a single frame. I feel that digital cameras subvert the creative process to an extent. With film, the photographer has to visualize the finished product and then figure out how best to achieve that. With digital it seems, one simply gathers lots of digital data and then manipulates it to achieve a (usually) technically correc
  4. Fast scopes are more sensitive to collimating errors than slow scopes. Slow scopes also tolerate lower quality eye pieces better. I suggest you use a permanent marker to place an ‘X’ on one of the primary mirror collimating screws and never adjust that screw again. When you collimate the mirror by adjusting all three screws the mirror will “walk” resulting in focal length error. Moving the primary in or out will change the focal point so that you will be unable to achieve sharp focus.
  5. I use an automotive jump start unit that works very well. It has two 12 vdc outlets, two 110 vac outlets, two usb outlets, and jumper cables. It has lasted five years thus far without issue and only cost $85.00 USD new from a home improvement store.
  6. While effective, desiccant is slow to work. In this situation my response would be to set the telescope up in a spare room and run an electric dehumidifier for a day or two. This will have the benefit of removing all the moisture from the electronics as well as the OTA.
  7. I have polar alignment scopes in two of my GEMs but don't use them. For visual, simply aligning the mount on true North and setting your latitude on the elevation guide is (essentially) the same as performing a polar alignment. I will grant that if you are using tracking motors a good polar alignment with the scope will yield better results, but if you are using GoTo, performing a three (or more) star alignment will eliminate any error.
  8. What I'm perceiving is a disconnect between when you are looking through the finder scope and when you are looking through the telescope, so I have some questions for you: 1. are you aligning your finder scope with the telescope beforehand? The center of your finder scope should be pointed at the same spot as the center of your telescope. 2. are you using any kind of tracking motors? If you are moving from the finder scope to the telescope too slowly (without tracking) the target is very likely to have transited out of the field of view of the telescope. As mentioned earlier, a
  9. The scope itself is probably worth $350.00 USD more or less. The OIII filter can be expensive - is it 1.25" or 2"? That makes a big difference, not to mention condition. A camera on a Dob has no value to me. If you are wanting to do AP, you need a whole other kind of scope. The EP's are nothing special, used, I wouldn't pay over $50.00 USD for any of them.
  10. Many years ago I made myself a very inexpensive Denver chair and it has served me well enough, though I've long wanted to improve on it in a few areas. About four years ago I built an observing chair very similar to this one from plans I found online. The only material difference I see is I used wooden dowels rather than pipe. I've decided to build myself this viewing chair because the Denver chair doesn't have enough height to use with my frac or cat, though I'll likely go with the wooden dowel rods in this build as well. Thanks for making this available!
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