Anyone using a Vixen GPD2 mount???

[hotspur]

Hi Folks

I am looking at buying a Vixen GPD2 mount,just wondering if there is anyone here using one,and what the think of it.

I have some concerns-not sure if its true,but I heard that they are now made in China,not Japan.

Also I had a read of some reviews of this mount on other forums,and some review were not good,one chap was very unimpressed.

I have a Vixen GP mount and it may just be good enough to handle imaging set up,if I use a small 'finder guider' or a guide scope no larger than a 66 megrez.

ok thanks for any advice,Chris

[garymck]

Hi,
I have a new GPD2,

the finderscope is marked made in china, the mount made in japan.

Performance is excellent. My guiding corrections are substantially better than my old - now gone EQ6 - the worst guiding performance of the Vixen is 3 times better than the EQ6, and the best 7 times better, and it is still not 100% tuned.

It is a quality mount. I am aware of 1 fellow in the US who had problems, but did have some private emails with him. The problem was not with the mount per se, but rather that there had been incorrect assembly at the Japanese factory, and he received no support from his local agent or Vixen Japan....

hope this helps,

cheers
Gary

[hotspur]

Thanks Gary!

Yes,that sounds like the same chap in America that had a big thread,about his issues.I did have a read of it-very long thread!

But from what I have found out along with your information,is that its very good.I,like yourself sold the NEQ6,I too found it to be rather budget made,and not to my satisfaction re tracking.My old GP can do 2 to 3 minutes unguided and still be rather passable,the EQ 6 after a few seconds of unguided photography looked like 'Mr Sqiggle' had landed!

Thanks for your help Gary,I am suprised :confused2:more people in Australia do not use this mount.

regards Chris

[garymck]

Chris,

I think people (like me of course) get carried away by the eq6's carrying capacity. I've now learned that I'd rather have a quality setup that is smaller, but which works faultlessly!! BTW I have fitted mine with a Synscan EQ5 goto system so I can continue to use eq mod for control. This is a straight bolt on addition, except for the plastic shroud that contains the connectors. If you go this route, also be aware that the gears on the motor drive may be slightly out of round (have seen a few cases of this) and give you the impression that PE is high. If this is so, simply try different positions for the gear that fits on the worm......Pic of my setup attached.

cheers
Gary

[MattH]

Hi Gary,
I looked at the picture of your setup and was wondering what kind of guide scope and guide camera is attached to VC200L. Did you have to modify the guide scope and how did you attach it to the dove tail. Thanks in advance for any information and/or pictures.
Regards,
Matt

[hotspur]

Thanks Gary,I have a Vixen GP mount and Vixen Skysensor 2000-PC currently on the pier in observatory.So will simply replace the GP and bolt the SS2K on the new GPD2 mount.

Matt asks you a good question,re your guidescope,could you let us know more about how you made it up etc,some more pics would be good.

you certainly have a lot of cables there,Gary!

cheers Chris

[garymck]

Hi,
the guidescope is a cut down 50mm 200mmfl Lumicon finderscope. It is fitted with a cheap 1.25" flip mirror with a QHY5 guider. It is mounted on a losmandy V series adapter from Bintel for $49.00

Losmandy V-Series Adapter https://www.bintelshop.com.au/Images/Stock/7823.jpg

I have attached several pics I think they are self explanatory but happy to answer any queries
cheers
Gary

[MattH]

Gary, thanks for the information about the guide scope. The pictures are invaluable. I am going to give it a try. Once everything is set up and tested, I will post some info and pictures.
Regards,
Matt

[DavidTrap]

Chris,

I seriously reckon that a finder guider like this is the way to go for you!

DT

[hotspur]

Yes David,it sure looks good,I think this looks like worth looking into

Gary has done a great job here,thanks for info Gary.

And I hope Matt posts some pics of his version.

Is there anyone else with a version of a 'finder guider' here that would

like to post a pic?

Thanks again Gary,cheers Chris

[Ross G]

Hi Gary,
I have also been looking at the GPD2 as a replacement to my Vixen Sphinx SXW whose performance I am far from happy with.

Have you tried unguided exposures with it?
If so, what has been the longest exposure and at what focal length?

Thanks

Ross.

[Phil Hart]

Not quite the same equipment, but I have a Vixen GP-DX that I bought from a previous owner while living in the UK about seven years ago.

A few years ago I bought an EQ6 and now only use the Vixen for widefield work only. I did some testing of the two mounts and in my case the periodic error of the GP-DX was +/-20" and the EQ6 +/-10" and the error on the EQ6 was much smoother. EQ6 can also clearly carry a lot more.

SS2K controller on the Vixen is much better as a stand alone controller (especially as you can disconnect the power supply and pick up where you were very quickly and easily).

YMMV..

Phil

[garymck]

Ross,

I haven't tried unguided exposures as I use (mostly) a long focal length scope - VC200l which would need guiding on just about anything! However I think at short focal lengths you could do decent length unguided images. My PE varies between total12 to total18 arc secs. The variation is caused by the Synta gears on the the drive I use being slightly out of round. Typical GPD2 figures are around total 15 arc secs - lots of people are getting this. It seems the GPD2 is significantly better than the older GPDX.

Some calculations:

guidescope = 200mm fl
guider pixel size = 5.2 microns square
guider image scale = 5.36 arc sec per pixel

now the mount tracks at worst depending on seeing at less tha .2 pixels rms, and at best .06 pixels rms. These figures are waaaaaaay better than my now gone EQ6

this means that the worst tracking I've seen is equivalent to slightly over 1 arc sec. My seeing is typically 3 arc secs (melbourne) so the mount is guiding/tracking very well.

If Pe = 18 arc secs over the worm period (10 minutes_) and is smooth and sinusoidal (as mine is) we could see a speed variation of 1.8 arc secs per minute. So the longest unguided exposure we could expect would depend on the local seeing and the image scale we were imaging at eg

lets say seeing = 3 arc secs, and pixel scale = 2 arc secs pixel (QHY8 on 800mm fl newt )one would expect, given excellent polar alignment to consistently get good 60 second unguided exposures, and perhaps significantly longer....

hope this helps

Gary

[GrampianStars]

My GPDX mount is superb with PE measured at < 7 arcsec.
Maybe a re-grease will fix your mount PE woes
http://arnholm.org/astro/gpdx/index.htm

[garymck]

Hi Just realised I had incorrectly posted my pe figures, I had posted +/- 12 to +/- 18 arc secs, this SHOULD have been total 12 to total 18 arc secs. ie +/- 6 to +/- 9. A moment of brain fade.....have edited post to correct....

sorry
Gary

[Ross G]

Hi Gary,

Thanks for the data on the GPD2. It looks impressive especially your PE figures.
Have you modified or "improved" the mount in any way?
It would seem that with the Vixen GOTO package the GPD2 would be a better buy than a Losmandy G8.
I dare say, it would even stack well against similar Takahashi mounts.

Thanks

Ross

[garymck]

Hi,

the mount is bog standard apart from a small adjustment to the worm block. It had been assembled with a slight tilt which had affected the PE adversely. After adjustment the PE was fine...

Gary

[MattH]

Hi,

Some time ago I posted a message where I said that:
1) I liked Gary's guide scope solution,
2) I was going to get a similar guide scope,
3) I was going to post some information about it.

So, here is my new guide scope. I have got it recently and managed to use (test) twice. It worked fine. It is not the cheapest guide scope, but:
1) It is light - it weighs only 1,235 grams,
2) It works as a perfect counterweight - the back end of VC200L is heavy, especially after attaching a camera,
3) It is versatile,
4) No modifications are required, just assembly.

The components are:
1) Losmandy dovetail plate adapter VA,
2) Borg mounting plate KD101 - it is a little too long, so I may chop the ends off (I can hear some voices telling me to do it but I am still hesitating :scared:),
3) Borg tube bands 7060,
4) Borg guide scope AG50B2A,
5) Orion StarShoot AutoGuider,
6) Three 1/4"-20 bolts.

Borg components were bought from Astro Hutech, other components from our local suppliers. I could not find any Borg suppliers in Australia - if I am wrong, please, let me know.

Cheers,
Matt

[dannat]

matt looks terrific..can you approximate the prices of the gear

[MattH]

Hi Daniel,

The prices for Borg components are as follows:
- mounting plate US$30
- tube bands US$79
- guide scope US$319

You can check all the prices on Astro Hutech web site http://www.hutech.com/

As for the prices of other components, you would have to contact our local suppliers. I think I paid approximately:
- Losmandy dovetail plate adapter $50
- Orion SSAG $300

Matt

[garymck]

Matt,

looks great, the Borg Stff is really nice ...wish I could afford it!

cheers
Gary

[hotspur]

Thanks Gary and Matt.

I am about to purchase the GPD2 this week.

Matt that set up you have for guiding looks amazing.

well done.

I will look at a similar style set up.thanks for all the information

Sounds like it has a lot of fans.

regards Chris

[hotspur]

Thanks Gary,your advice was most helpful,I installed the new GPD2 on the pier
yesterday,and started putting the cables back in order.

Even managed a basic test run between clouds,all went smoothly,and will even be better after a proper PA.It will be good to have a slightly more heavy duty mount than my older GP.

Thanks Matt,that Borg finder looks very neat.Might look at one of those,when funds allow,Although the home made 'finder guider' sound like they do a great job too.

Here is a couple of quick images of the new set up-Chris

[garymck]

Hi Chris,
looks nice! Hope you enjoy your new mount as much as I do with mine. It's soo nice to have a mount that actually tracks properly......
cheers
Gary

[MattH]

Hi Chris,

Congratulations on your new mount. As for the home made "finder guider", most certainly it will work fine. I have bought the Mini Borg because I do not have too much experience as for modifying things (read: too lazy).

Regards,
Matt