Should I get a Vixen SXD AP Work
Posted 10 April 2011 - 11:15 PM
LXD-75, Eq-6( Great mount Very heavy) and now a CG-5
I like the CG-5 for It's portability and is quite good up to about a 15 lbs load for guiding and AP
The Vixen looks attractive since it's load is 50 lbs Visual
probably around 25lbs AP?? it also has PEC and assuming the Periodic error is considerably less than the CG-5
The Tripod looks unstable to me ??
Help w comments please
Posted 10 April 2011 - 11:20 PM
Keep in mind the 50# rating includes the counterweights in this case.
Posted 11 April 2011 - 02:38 AM
Note that the problems on the SXD are not mechanical (like any Vixen, they are mechanically great) but in the electronics. Some folks have fixed this by getting the "NexSXD" board (about $300) which replaces the Vixen electronics with a board that is compatible with a Celestron handset (you need to buy the Celestron HC separately). This gives you the famous Celestron All-Star Polar Align and gets rid of the DEC guiding problems, but adds to the cost.
The good old EQ6 (and CGEM) are still considered better choices overall. I was choosing between the SXD and CGEM and went with the CGEM.
Do note that the SXD is rated for 15kg by Vixen Japan. The 50lb figure is grossly overstated. So assume around 10 for imaging.
The DEC guiding problems on the SXD is one reason why the Vixen GPD2 is still popular.. older technology but well-known and doesn't misbehave.
Since you hate the weight, the iEQ 45 might be a better choice, there are enough users out there getting pretty good results with it.
I'm afraid if you want light-weight and capable, the next step up is an A-P Mach1. (the reason I settled for a CGEM)
Posted 11 April 2011 - 10:36 AM
saved me some major $$$$$ 1650.00..Will keep what I have For $450.00 you can't beat it
How is the periodic error on the CGEM?
Posted 11 April 2011 - 01:41 PM
As a faint voice in the void, I have an SXD and find it fine as an AP mount at the focal length I 'work' at (500 - 650mm). My latest photo is linked below
I guess its not a Mach 1 (maybe one day) but I don't seem to have problems others have reported with starbook. I have a vague recollection that someone once said that the sudden jerks in dec were a feature of starbook trying to correct for polar misalignment. But I only ever sync to one star when doing AP so i may just avoid it (goto is pretty much spot on anyway - usually in the frame). Don't use PEC btw.
It is rated for only about 15 kg and the tripod seems fine for the weight I have on it - strangely the small extension pier is a weak link.
The advantage for me is that it is light. I don't have a permanent set up but i can easily carry it out side with all the equipment attached - that's one of the main reasons i got it in the first place.
Posted 11 April 2011 - 04:00 PM
Posted 11 April 2011 - 06:10 PM
My use case is a C9.25, according to one of the posters here who has an SX-D, that mount is great so long as you stay under 8-10 kg (which the C9.25 is not).
I haven't measured the PE, because I live at a low latitude and the CGEM doesn't go that low (still trying to have a wedge made), so the tracking accuracy sucks. GoTo's are on the dot though.
Another thing about the SX-D is that to get good GoTo's you need four pairs of alignment stars (2 pairs on each side of the meridian). So far I'm only using 2-star align on my CGEM (2 stars on one side of the meridian -- and that's with a 15-degree latitude misalignment) and its good enough to put my targets inside the FOV of a 32mm Plossl on the C9.25 (about 0.7 degrees).
I will note that the C9.25 is 2350mm focal length which is very, very long. I haven't tried imaging with this setup. At the usual 400-600mm focal lengths imaging is much simpler (and I have a Vixen GP for that, which is more than enough for my teeny tiny 70mm refractor).