"My advice is free and worth every penny!"
AP 130EDF-GT & AP Mach1
C14-XLT & AP 900GTO
John Hayes, Ph.D.
Adjunct Research Professor
College of Optical Sciences
University of Arizona
Quote:Hi Chris, I've thought a lot at your reasoning on the theory that the guide scope should turn around the main mirror, so emulating a giant off-axis guider. Hence my question: Why the test with 2 de-rotator field has worked?I think because in reality the optical train of the main image has worked exactly like an OAG, relegating the guidance of the DSI for the sole purpose of keeping the guiding star of the AO-7 in the range of action of his mirror. In fact, the main image was de-rotated together with the reference star in the AO-7. Even in the traditional configuration, LX200 tracking ago without an autoguide and without a second de-rotator field, leaving the task at AO-7 of re-center the guide star with bump mount, and all of this works very well. In my tests the second de-rotator was used exclusively to keep synchronized the two images guiding (DSI and 237sensor SBIG), otherwise, even with DSI guider but without the second de-rotator on the ED80, the mirror AO-7 would have lost quickly her working reach. This is the conclusion I have arrived, but I'd like to know your opinion.Marco
Quote: I reset the OAG to square with the Alt-Az mount between exposures or timed-constrained groups of exposures.
Too many scopes, not enough time...
Quote: Quote: I reset the OAG to square with the Alt-Az mount between exposures or timed-constrained groups of exposures. Hey Chris,How often (time wise) do you end up resetting the OAG?Dave
Quote:Hi Chris, it is difficult to explain these concepts in words, but I try. The tracking overall performed in the test, goes beyond the conventional way of understanding the guiding parallel as report: guiding/imaging = guide scope/main telescope. In reality what I tried is not autoguide intended as only autoguide with guide scope and imaging with conventional SCT telescope, because the main guiding (than the real), is dictated by the AO-7 that works radially with the main picture, therefore the second guide star (the real reference guide star) it's monitored by the second sensor by St2000XM, so radial . DSI serves only to maintain a costant tracking mount soft, but the real guider remains only the 237 guide sensor of ST2000XM that works in symbiosis with adaptive optics and main de-rotator field, therefore all together (all the optical train) rotates and autoguide works radially, so perfectly compatible with the theory.Another point is square and recalibrate autoguiding after a certain overall time tracking. In previous other posts I explained that MaximDL, with adaptive optics used in the conventional way (with bump mount), is able to maintain perfectly an offset over 75° of rotation image guide, providing more than 3 hours of consecutive exposures without having to square and recalibrate guider. This very important point, I'm not sure that PHD both able to do.Marco
Quote:As I have explained in other posts the reason is simple. A LX200 12 "or larger is much easier to mount and unmount all times in altazimuth mode and even much more stable, respect to polar configuration with wedge (I do not have a permanent observatory) . Moreover there is no need to do the polar alignment and drift. I keep all the accessories mounted on the telescope (what you see in the picture), so when I start the photo session i just have to put the telescope on a tripod, connect the cables and so I'm ready to shoot in less than 15 minutes. This is really priceless for me. Surely is not the cheapest solution, but this is a secondary factor for me, because my priority is to have a good size of telescope and a good focal length lens (I love photographing small galaxies), easy and quick to make operational and especially that it works perfectly.Marco
Meade 8" LX200GPS
Meade Super Wedge
Thousand Oaks Off Axis Solar Filter
SharpStar 65EDQ (same as AT65EDQ) 9.25" Homemade dobsonian with 1/13 wave self-made mirror. AT6RC/Celestron ASGT http://www.astrobin.com/users/tyblakesley/