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Multiple Star Alignment for Takahashi Mounts

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#1 Tim C

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Posted 29 May 2009 - 07:27 PM

Hello,

I recently acquired a Tak EM200 Temma II mount. I was curious if there is any reasonably priced (or free!) software available to permit multiple star alignments with these mounts to improve "all sky" pointing accuracy. These mounts rely on accurate polar alignment and syncing on one star. This is simple to do and works very well in the same area of the sky but when I tried a meridian flip the last time out the goto's are off a bit and require you to sync on a different star on that side of the meridian to improve accuracy. This isn't a big deal and I'm not unhappy with this but would be nice to be able to align with multiple stars on nights where I'm doing a lot of visual observing and slewing a lot. I'm aware that you can do this with The Sky and T Point but that's almost $400 together. Astromist will let you do a 2 star alignment but only works on a PDA.

Someone got my hopes up recently by posting a question on the Tak forum to see if anyone would be interested in EQMOD for Tak mounts but there were only a couple of replies (including mine) and it didn't appear to go anywhere.

Tim

#2 Jaxdialation

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Posted 30 May 2009 - 12:29 AM

I can't think of a free option for you.

#3 Tim C

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Posted 30 May 2009 - 07:21 AM

Thanks. Kinda what I figured but never hurts to ask. What kills me is that The Sky and Tpoint are much less expensive for the PDA versions but I'm using a netbook so would be about $370 for the XP versions.

#4 jrcrilly

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Posted 30 May 2009 - 07:30 AM

Thanks. Kinda what I figured but never hurts to ask. What kills me is that The Sky and Tpoint are much less expensive for the PDA versions but I'm using a netbook so would be about $370 for the XP versions.


Maxpoint is less expensive than T-Point, and it may work with the planetarium software you already have (website says it works with any ASCOM-compatible software).

#5 tim53

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Posted 30 May 2009 - 09:42 AM

I would think that any routine like TPoint would be frustrating to have to do with a portable mount (not permanently pier-mounted).

Also, what kind of OTA do you have on the mount? Probably the biggest culprit in flipping across the meridian would be the optical axis isn't quite perpendicular to the Dec axis. It might be possible to adjust the collimation of the OTA to be closer, but I would think that wouldn't be worth the effort (and am having a hard time picturing how it'd be done).

I have 3 Tak mounts that I move around to dark skies for astrophotography, and I don't find it too troublesome to hop to a bright star after a long slew, sync on it, then go to my image target nearby. I use TheSky6, Voyager 4.5, or good old Tracer2000 for this.

-Tim.

#6 Chris Curran

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Posted 30 May 2009 - 10:58 AM

If you're only having (big) problems after a flip, your issue is orthographic in nature. You can buy software to "fix" that, or you can "fix" it with shims and a bit of effort. Or do what I do - nothing. :) I just live with re-syncing when I flip my EM-200.

#7 Tim C

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Posted 30 May 2009 - 11:03 AM

thanks all. Tim, I don't find it too troublesome either to sync on bright stars - especially with doing photography because I use a bright star to focus on anyway before going to the target. That's why I'm not willing to spend much $$ on a program but would probably use it sometimes when doing visual. What's better in your opinion - The Sky 6 or Voyager? I use Starry Night Pro now to control the mount but it sure is slow and has a tendency to freeze up periodically. Cartes du Ciel work very well but it's missing some features I like in programs like Starry Night.

#8 tim53

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Posted 30 May 2009 - 11:25 AM

I guess I'd give TheSky6 a slight advantage over Voyager 4.5 because of the ccd frame option that also displays the guiding ccd's view (I'm using an SBIG ST2000XM). It is fabulous for getting the true f-ratio (my C-8 with the 6.3 reducer really winds up at f/5.5 with the SBIG) and finding guide stars.

Voyager also allows you to display the field of a ccd chip, but last I checked didn't show the guiding chip's view.

I have found only one instance so far where Voyager sent the mount in the wrong direction when slewing. But I may have initialized it on the wrong side of the meridian or something. EquinoX seems to "forget" more often than other programs I've used (note: the forgetting may be more human error than a problem with the software).

TheSky6 remains, for me, the least likely to have problems or send the mount in the wrong direction, of the aftermarket software.

Tracer 2000 is free, of course, and written specifically for the Tak mounts. I've never had a problem with it, once I initialize the scope properly. It's even got a decent display of DSOs. Except for the lack of a ccd frame display, I find it as useful as the other programs, just not as pretty.

Display-wise, I think Voyager 4.5 beats them all. Smoothest zooms of the bunch (TheSky6 seems to display objects in jumps, with certain settings seeming to be overcrowded with objects/stars for the zoom and others to be underpopulated).

-Tim.

#9 Chris Curran

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Posted 30 May 2009 - 01:50 PM

I use TS6. It works and it interfaces with Maxim.






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