A review of mounts

[gregbradley]

I have/had the following mounts:

Meade Alt Az LX90 and Celestron Nexstar 11GPS
Vixen Sphinx
Mountain Instruments MI250
Takahashi NJP with Temma 2
Paramount ME


Meade and Celestron Alt Az.

Great for go tos. The Nexstar was an awesome visual scope. Easy to setup - the GPS did everything and accurate go tos were amazing. Great for a visual tour. Amazing really what those scopes do. One of the best planetary views I have had was from the Nexstar 11 GPS.

No good for astrophotography though. Not that I tried very hard.

Vixen Sphinx.

Well I thought at AUD$3600 I was going to get fabulous tracking and I would be able to do astrophotography with it. I was not able to but I think you can now.

Axes were stiff from the factory and needed to be handled by myself. Dealer was not very helpful and even rude. It was better than the Alt AZ
but not good enough. I tried autoguiding but it failed.

Good for visual use with a light scope.

Mountain Instruments MI250.

Going up considerably in cost. I think this cost around AUD$6500 or so landed 2nd hand.

A jump up in quality. It used the Gemini system and Losmandy motors.
It had diamond grease honed gears. Clutches were loosened and tightened by allen keys - first thing I didn't like. I drove all the way to my dark site once to do visual. I didn't bring any allen keys. I set it all up and could not use it visually as I could not move the clutches. Ouch.

I also got the 8 inch portable pier. This is an awesome pier and I still use it today. Solid and nice looking.

I found Gemini complex but could be learned. It took a lot of effort to get a synch going so go-tos were accurate. Many stars and synchs.
If you missed parking it you had to do it all again and it took ages to synch up.

Overall quite an accurate mount but a bit rough and home made in fit and finish. Not Japanese quality.

Takahashi NJP.

Ahhh, sigh of relief. Finally a mount that worked, was user friendly, had really low PE and was very easy and fast to use.

One or 2 stars synched and bang this baby is ready to go. Light, accurate, simple. No "complex" Gemini, easy. Put the fun back into imaging. Many years of service so far. Best purchase so far. Wonderful mount.

Can handle up to an RCOS 12.5 inch or a TEC180 refractor.The EM400 (its replacement model) is probably even better as it is a bit beefier.

Does not have periodic error correction available though.

Paramount ME - to be reviewed. About to use it soon.

Greg.

[Paul Haese]

Great reviews Greg.

Owning the EM400 I can attest is a lovely mount. Everything is a pleasure to use except two things. The hand controller is really basic and should have a north/south switch for changing and maintain hemisphere. The other thing is that the mount does not have a home position on the encoders. This means each time the mount is turned on one has to do another star alignment. Robotic work is not possible as a result too.

I have been eyeing off the PME for some time and look forward to your review.

[Tandum]

Paul, The temma ascom driver (http://ccdastro.net/temma.html)lets you park the mount.

[Hagar]

Great reviews Greg but I can't understand your concerns about the Gemini system. It's so easy once you have used it a bit. What could be simpler, one button select menu, 2 buttons to scroll through the menu and again the select button to select. Basically the up and down buttons are the scroll directions, the right button is the select and the left is the back or cancel button.
I find I can control most options without any extra light and with ease. The star alignment can appear very long but in reality I can setup my mount and do a cold start which requires a full star alignment and model build and usually get very good pointing accuracy with only a 3 star alignment. For greater accuracy a five star alignment with 3 on one side of the meridian and 2 on the other places selected targets dead center every time.
I have used the park/warm start and one star alignment on many occasions with no problems. I would consider a gemini as one of the best/ most accurate control systems I have used and would not hesitate using it on another mount.
It is what you get used to using and as a field mount does not require the Sky or any other planetarium program to get good results or even to work at all.
Like every mount a good polar alignment is the key.

[gregbradley]

Yes that is true. The hold down the S1 key when you turn it on to let it know you are Southern Hemisphere is very Japanese isn't it?

As Paul below mentions if you use the Chuck Faranda driver you can park your mount so next time you turn it on it unparks and keeps all the alignments from last time. Plus it has a timer which I use all the time.
I always set the timer to stop tracking at a certain time otherwise I could sleep in and go out and find my mount gnashing the gears. I think it
actually won't do that but you could whack your scope on something at an odd angle. google chuck faranda temma driver.

Also there is a more featured Temma hand controller available from a 3rd party. I saw it mentioned on the Tak Uncensored yahoo group.





You are right of course the Gemini is a clever and logical system. It was a bit easier with the version you can run off your laptop. You could see the tree of commands. Gemini seems quite similar to me to the Meade hand controller. Its just that the Tak NJP was much simpler and one or two synchs got accurate go-tos. I guess I had trouble with setting the slew limits. For some reason I kept getting errors saying the slew I wanted was exceeding the slew safety limits a lot. Probably didn't set something up properly.

As you say its only as good as the polar alignment.