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Semi-permanent mount questions

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#1 nitegeezer


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Posted 25 October 2013 - 12:09 PM

I am wanting to do some astrophotography this winter and have set up my scope where it will be protected but will only have a view of the northern sky. I have built an enclosure that goes around just the scope so I can heat it and keep moisture away when not in use but it also means that I must remove all accessories before putting it to "bed". I have several questions and did not have much success with the search and don't want to hijack other threads. Starting out I have not used scope park as I also have questions about that, and I am mounted on a wedge.

Starting out each night, I put the scope in "home" position, dec at 90 and ra at 0. When I do the one-star align, the controller first slews to where Polaris should be and asks me to center it using only the adjustments on the wedge. Apparently I am not setting "home" accurate enough as each time I power up I have to readjust the wedge, even if I do a quick power cycle just to test this out. It appears the encoders are for relative position and not absolute position so how do I eliminate wedge adjustment without giving the encoders false information?

I have been using Arcturus to align with, but last night it was below my local horizon. Since I am looking at only the northern sky, I can see the dipper great but I did not recognize the stars it wanted to align on and all but two were out of my view anyway. Is there any way I can force an alignment using a star I know?

I think some of my problems could be solved using the "Park" position but I am a little confused by the manual. Can I tell the scope where I want it to park or does it decide? If I can tell it, what is the procedure? Since the encoders appear to be relative, I would suspect that I cannot loosen the clutches to store the scope where I want it, is that correct?

Coming out of park, is there any alignment procedure or am I good to go? I should add that the gps has trouble getting enough satellites so I have to enter the time manually.

I am dedicating this winter for just learning how to operate for photos, so I do't want to but additional equipment should I find that I prefer just visual work. I have a Meade LPI and it claims I can use it as an autoguider. Using only Meade software, I figure that is my best start to have everything work together, I can get the Autostar Suite to connect to the scope and the software hand controller works. When I use either the older LPI software or the new Envisage, the imaging window will not connect to the scope and I watch the "tracked" image slowly leave the screen. Any idea what I am doing wrong?

Until I get the "park" working, it does not make any sense to try to drift align as that would only be good for one session. My tracking usually changes only in the dec axis as the image drifts up. I have heard this can be corrected but have obviously never tried it. This is a very slow drift so is it something I need to address or is this something that autoguiding will correct?

I know my location is not ideal, but this is the only way I could protect my scope from heavy snowfall as it is under my deck roof. If I am going to do this long term, I know I need to build an observatory where I have better sky access, but I don't want to make that investment should I determine that I don't enjoy photography and for visual all of my problems basically go away.

I would appreciate any and all inputs.

#2 backroadrider


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Posted 26 October 2013 - 10:18 AM


You should be using the "Park" utility to shutdown your scope after each and every use, even if you simply turn it on and then want to turn it off. "Parking" your mount will retain all of your settings (location, alignment, pec, drift alignment, etc.) in non-volatile memory.

When you park the scope, it will return to its home position and then force you to shut it off. The only way I know to "tell the scope where to park" would be to change the home position but you don't want to do that!

When you fire your mount back up after parking, Autostar should default to the "Object" menu and you can simply "GoTo" your desired target. Once you select a target, Autostar will need to know the current date and time (from gps) so it can update it's stored celestial position data, and should then slew to the target. If, for some reason, the scope misses the target after slewing is complete, simply center the target with the keypad and, after it is centered, hold down the ENTER key for 2 seconds, release it, and then press ENTER again in response to the "Sync?" message.

If the scope isn't accurately polar aligned, which it won't be (see below), then you might want to perform a simple one-star alignment when you wake it up from the "Park" position. The best way to find a suitable star is to use some form of planetarium software to identify a bright star that is in your field of view and pick that as the alignment target. I recommend a smartphone app like SkySafari which you can load on your phone. The professional version of SkySafari (SkySafari Pro) can even be used to control your mount.

I have never used the Meade Autostar Suite so I can't comment on that. However, you will quickly discover that the key to accurate tracking is accurate polar alignment which is much harder to attain than you might think (centering Polaris is only a start!). Much has been written about polar alignment and if you simply search on "polar alignment" you will find a weekend's worth of reading. There are also excellent software tools (like AlignMaster) that can help you get to within an arc minute or two of perfect alignment.

ONCE YOU HAVE YOUR SCOPE ACCURATELY ALLIGNED, you can use one of the many guiding cameras and autoguiding software packages (again, I am not sure about Autostar Suite) to keep your target centered. However, while autoguiding will manage to keep a poorly-aligned scope aimed at a target, you will still generally have way too much movement of the target for quality astrophotography. The bottom line is spend some time aligning your scope and then "Park" it!

Hope that helps.

#3 LoveChina61



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Posted 26 October 2013 - 10:38 AM

You should not have to adjust your wedge each time at all. Drift align or use another polar alignment method to get the wedge polar aligned as accurately as possible. Then don't touch the wedge adjustment bolts ever again!

I mean, you might want to do another drift alignment in another 6 or 12 months to finely tweak it again, but adjusting the wedge bolts is not something you do each time you power up the scope.

I am not really familiar with the Park routines mentioned above, but once any fork mounted scope has been properly polar aligned upon its wedge then it simply needs to know where it is pointing when you begin using the scope each night. Assuming that you already have the time, date, and latitude/longitude set correctly in the scope's handbox, all you have to do is a single-star alignment to tell the scope where it is pointing. For example, Vega is a good star to sync upon during this time of year.

After that you are all set to go for an entire evening of accurate GoTo's!

#4 jrcrilly


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Posted 26 October 2013 - 11:11 AM

The home position (dec 90, RA 0) is where the controller expects the mount to be before slewing to the first alignment star. The park position isn't related to that in any way. The park position is where you want to telescope to be when not in use. It can be any orientation. You would first star align the mount so it knows where it is, then slew to your desired storage position (using the motors). Then set that as your park position, select "park", and power down. You only need to set the position once. At the end of later sessions you would simply select "park" and it will slew back to that position for you and instruct you to power down. On power up the next time, it will be ready to go once time is re-entered. It won't need to go to the home position and you won't realign anything.

The wedge isn't related to any of this. Once the wedge is aligned you won't mess with it again until you tear down and reassemble.

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