Quote:Actually the advertised load capacity of the mount is 40 pounds and my main and guide scopes plus mini-dovetail and tube rings weighs 38 pounds. So that's two pounds below the advertised weight (not including counter weights).
Quote:An observatory would be nice if I have the time and space to build one. I have a Celestron focal reducer. Right now the only place I can mount it is right at the rear cell of C-11. But I have to have about 3" - 4" extension to the camera because the diameter of Orion StarShoot camera is so big that it hits the JMI Motofocus without the extension. I think the extension is causing excessive vignetting. I have not yet figured out how to place the FR at the camera or in between the camera and extension. I am sure I can but I have not been looking hard enough.Actually the advertised load capacity of the mount is 40 pounds and my main and guide scopes plus mini-dovetail and tube rings weighs 38 pounds. So that's two pounds below the advertised weight (not including counter weights). Peter
Money can't buy happiness, but it sure makes living with misery a lot easier!
Quote:Uncle Rod,Yes, I am imaging at F/10. I already tried f/6.3 focal reducer but I get huge vignetting probably because I have to use about 4" extension in order to prevent from the camera to hit the JMI Motofocus. The diameter of StarShoot Pro CCD camera is huge. The reducer was connected to the rear cell first, then 4" extension and then the camera. I can't yet figured out how to mount the reducer between the 4" extension and the camera. Will it work better if the reducer is mounted right in front of the camera?PeterEDIT: Please define "East heavy". Does it mean when counter weight shaft is at horizontal and pointing east and counter weight end is heavier than the scopes?
Uncle Rod Uncle Rod's Astroblog: http://uncle-rods.blogspot.com/
Quote:This was my original target before I started having problems. Later that night I imaged M1 as shown earlier in this thread.NGC891C-11 at F/10, 2800mm F/L2 frames of 15 minutes each1 frame of 10 minutesImagine what this would look like if I had image it all night with 15 minutes (or longer) each frame!!!! If I only knew exactly the issue I am having. Peter
Quote:I saw this in Cats & Casses thread about a pretty cool Off Axis Guider:http://www.taurus-tech.com/tracker.htmI read several reviews via Google and it received pretty high marks. I have read many people hates OAG but this is a really cool gadget.OAG could eliminate the need to use guide scope mounted on main scope and save weight and possible greatly reducing flexure.Peter
AP130EDT f/8, Tak FSQ-106EDX, Pentax 75 EDHF, SVQ100 Apogee U8300, U16, A8050, A694 Orion Atlas EQ-G Mount with EQMOD AP900GTO in an Exploradome
Quote:Not to be argumentative but I just want to bring back the mirror flop issue. My friend that just dealt with the problem showed me image progressions as he imaged from ~45 degrees up to the meridian and his stars got progressively worse and peaked as he approached the meridian. Theoretically, I think it makes more sense that the mirror slowly shifts position rather than getting to the meridian and then completely/suddenly shifting all at once. As a side note, all his imaging is with a 6.3 reducer.I know some other more experienced people here have stated that your problem probably isn't mirror flop and considering that my experience is more 2nd hand I'll defer to them but I think when all else fails you can't completely rule mirror flop out.
Quote:Uncle Rod,Thanks for the suggestions.I thought if the object I want to image is dim, I need to increase the exposure for each frame. I also thought stacking more frames simply increases signal to noise ratio, not necessarily make the object brighter. That's why I thought I needed to expose NGC891 a little longer for each frame. I can't even see NGC891 with my naked eye using eyepieces. Probably because of some light pollution from casinos in Reno. I had to expose about 100 seconds just to barely see if my Atlas GOTO mount found it and it did! It was almost dead center. Then it took me about 10 to 15 minutes to figure out which directional buttons to use to center it.I think I will sell the JMI Motofocus and get Moonlight focuser with focal reducer adapter and motor so that the focal reducer is at optimal distance from the camera and closer to rear cell of C-11.Peter
Quote: Keeping an object perfectly immobile at 250X during long poses despite vibrations, wind, backlash, drift, mechanical imperfections in gears during tracking (Periodic or not periodic error), seeing turbulence, guide coorections, mirror shift, piggyback guide system shift, software errors, feet in the cables, defocus....did I forget something ?, this requires serious mounting.
LX850 blog: www.LX-850.com
personal website: www.wadsworthobservatory.com
Quote:I am beginning to agree with the previous three posters. Maybe OAG is my ne
Quote:So what's a good OAG besides the $300 one from Taurus?[\quote]The moag is good but expensive. The Lumicon easy-guider may be ok, but I don't know first hand. And I recently learned of this one: 9mm OAG Quote: which looks interesting.These are all metal and heavier - and harder to modify. The main thing is that the pickoff mirror be big and close to the guide camera so that you get less vignetting and see fainter stars. You may have a trade off between a large mirror and some vignetting of the main image - but much of that will go away with a flat.There is a big added cost from the front and back adapters, so keep that in mind.I have only used the taurus stuff and MOAG myself. Quite a spread of prices. Well - it's an investment.Frank
Quote:Peter, nice M27 image.Out of curiosity, how many counter weights, do you use? I deforked my CPC 1100 last week end in order to put it on my EQ-6 Pro and I was surprised how many counterweight were necessary (at least 47 pounds with the Orion 80ED on top used as a guide scope). I had not yet installed the imaging and guiding cameras. It would have been even more with them. How much weight can the Atlas handle?
Quote:Peter, one thing about your problem is that drift alignement will be necessary regardless of whether you use a guide scope or OAG. The guiding does not compensate for field rotation. If your polar alignment is off, the guiding star will be round but all other stars will show the effects of field rotation.
Quote: But I do not see much field rotation on my frames. I see stars shift in between frames. This looks more like flexure issue to me.
Quote:Perhaps, you have both problems. But I doubt that you will be able to image longer than 10 minutes without doing a drift alignement. Anyways, your results are better than mine, so I am not sure that I should be giving you advice...