The Vixen GPD2, Instead a critical review!
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If you came to this page looking for the old page:
"My Vixen GPD2 Mount Problems!"
As you can see it's gone! I have been meaning for a while to come in and do some updating work on my web site, and taking down the posting of my right out of the box early troubles with the mount is a part of that updating procedure. The consequent run a round, complete failure of Vixen Optics/Vixen Japan in their customer support, and the outright misinformation given to me by Vixen Optics support over the problem told me what I needed to know about any future dealings with either one. I posted the article to pass on to any buyers who might be wary or want to check out any potential problems with either the product or people behind it… I feel that has been accomplished and it is long past time to move on!
So, with that said I'll post up my experiences and opinions of the Vixen GPD2 German Equatorial Mount. As has been covered here previously I experienced some issues right out of the box with the unit when I first received it. The trouble boiled down to some poor assembly of the mount, "out of the factory"??!! The mount had a problem of the Right Ascension Axis tightening up on it's own to the point of faulting the Meade Autostar motors by the 5th or 6th slew of an outing. I spoke with a Mike Fowler from Vixen over the axis being way to tight earlier when I first tried to use the mount & during the phone conversation and after he figured out I had experience with working on this type of mount he told me he would be comfortable with me doing the repairs, rather than sending it back. I did the basic fix of stripping the mount down to the exposure of the R.A. Axis nut, releasing the set screws & backing it of ever so slightly to the point of good axis stability and smooth rotation. As stated after putting it back on the pier and running a couple of full rotations to test everything it ran fine. Unfortunately as the night went on & a few slews later it would tighten back up & … motor fault. After doing the back off procedure again & the same result, well that's when the support problems started with no or slow responses…. All covered earlier in the previous article.
Bottom line is I ended up disassembling the entire mount, since help was nonexistent & my only other response to that time was I thought you had it fixed. Long story short (too late!) once I had the mount torn down & cleaned up I found the problem to be the axis nut threads in the areas where the set screws locked in. They were completely blown out with shards & bits of the thread jamming up things as well as an area where there had been several attempt to set the screws in very deep into the axis. I took the axis itself and performed a light cleanup of the damaged areas with an end mill in the fabrication shop I used to work PT for. Just enough off of the threads to remove the damaged areas, then finished out with a good steel wheel brush on the bench grinder. This did the trick on the damages to the axis & threads. I bought new set screws from a local dedicated fastener store & when I put it all back together it ran flawlessly….. Finally it was running like it should have in the first place. Now on to the actual review, sorry to dwell on the initial problems, but some explanation is to me required, rather than just "There were some initial problems with the mount & Vixen."
Once fixed the, mount started performing very well indeed for a light weight economy German Equatorial Mount. I had a pretty good load on the mount right at 27 Lbs. without the cameras. It was mounted on a permanent 5" OD schedule 80 steel pipe based pier, anchored to a 20" x 20" concrete footer 40" in the ground via 4 one inch anchor bolts. Obviously the mount was riding a very stout permanent pier arrangement which helps tremendously with a load on about any good quality mount still under its max load capacity. Under these conditions the fixed Vixen GPD2 handled the load of equipment well and without complaint. My imaging from this platform was always pretty steady, at any altitude angle with that load. As can be seen from this image:
Messier 8 The lagoon Nebula, Vixen GPD2 (Meade AutoStar Driven)
This was a set of 3 minute exposures as stated on the gallery page. Well, 3 minute image isn't so much you might say, but consider this. The long vertical diffraction spikes you see in the image are from the telephone lines that run along the back edge of my property. The angle of approach on this shot is low from my location, the mount is handling all of the weight at near maximum angle of the principle stress. (I think I stated that right…. If not I will be sure to get plenty of corrections from those who know!) Anyhow you get the ideal! My old LXD75 just could not handle a shot like this very well, but then it was considerably cheaper back then too!
I did do a few measurements of the period error of this mount as well, and I have to say it was impressive for an economy level equatorial mount. Best I ever got an average of 15 A,S. peak to peak, and the worst 18 A.S. I did the measurements using both PEAS & EQMOD with PHD doing the recording. More importantly though was the mount took auto-guiding with some very smooth guiding curves. Once the initial problems were fixed I never had another problem out of the mount. It is truly unfortunate that Vixen never followed up on the situation, because it would have smoothed things out to a little more satisfied owner & less hostility in any mentions of it to them by folks.
You can peruse through my astrophoto albums here on the site to see just how capable the Vixen GPD2 was, any image listed in the description as having been obtained with "an Autostar Mount" was taken using the Vixen GPD2. It was basically run, slewed, tracked, and controlled by a Meade Autostar 497 hand controller & drives along with a direct serial connection to a PC via the Autostar 497 handset. After the debacle I decided Vixen would not be credited with any of the AP obtained by the mount since they basically disowned it. The marrying of the Autostar to the mount is another point in the Vixen GPD2 mount's favor; it will marry very well with about any mount computer control GoTo units out there made for the 10 minute worm gear 144 tooth gear GEM. The Autostar ran the Vixen GPD2 just about as flawlessly as Autostar can run. Given the much higher precision of the gearing in the Vixen GPD2, the Autostar GoTo & tracking was actually quite impressive as compared to the variety of other makes of similar Vixen clones I've used in the past. So I'd say in my opinion, the Vixen GPD2 is basically the top of the pile of light weight German Equatorial Mount economy mount heap! Here's the Pros & Cons in review and opinion of the Vixen GPD2.
It handles a better load handling than the rest of the mounts in its class:
It has much better average period error than the rest of the mounts in its class:
It has much more accurate gearing as demonstrated by the P.E. & GoTo slews:
It can be married to several different mount control units built for this class of mount:
It is very stable on a good tripod or pier platform.
Higher price than the others, but then it makes up for it in the Pros:
Dismal customer support should you be so unlucky as to get one with a problem:
If you are in the market for a good well-made light weight economy German Equatorial Mount then you might consider this one. I'd recommend finding one on the used market as Vixen has as of this writing discontinued the GP2 & GPD2 series mounts.
Mark Jordan (AKA The Mad One)…. As a hatter!