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Polar alignment for astrophotography


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I am in the planning stages for astrophotography, aka total beginner, so hoping this doesn't sound stupid. I have a Celestron AVX equatorial mount, which does have the All-Star polar alignment thing, that says it is "accurate enough for short exposure prime focus planetary imaging (a couple of seconds) and short exposure piggyback astroimaging (a couple of minutes)." From what I have read, you kind of have to be able to align on Polaris to be accurate for astrophotography. The problem is that in my backyard, the north is completely blocked by trees. How would I go about getting proper alignment? Is the Celestron Starsense any good or would it even solve the problem? Someone in another thread of mine also said an autoguider is necessary so that is on my list also.

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Without knowing a great deal, visual only in reality, the option open to you is Drift Alignment.

Now the process is a bit convoluted and I have no idea on the details. At a guess (total) you would set the mount up level (not necessary but maybe essential in this case), then set the latitude - if using the dial on the mount then the level of the mount is essential. Then aim the mount North - true North not magnetic North as there is likely a few degrees difference. All this is aligning the mount, not the scope.

Then I have to drop out and leave you to get the details of drift alignment. As people do it fairly often in the imaging I guess it sounds worse then it is and is likely a case of performing 3 or 4 iterations to get it complete.

Starsense is as best I know for the goto alignment which relates to the scope, not the mount. It might help but all I ever read is of "problems with Strarsense".  There seems to be some almost magical way of doing things. Considering I can do a manual alignment for goto on my scopes in 2 or 3 minutes I cannot quite see why people bother.

Slight concern is: "accurate enough for short exposure prime focus planetary imaging (a couple of seconds) and short exposure piggyback astroimaging (a couple of minutes)."

That is not very accurate, I could probably put a DSLR on a scope on a fixed tripod and get a 10 second exposure, also the "periods" seem back to front. I would have said a couple of seconds for astroimaging and a couple of minutes for planetary. Without guiding I cannot see you getting a couple of minutes, with good polar alignment but no guiding I would have said 60 seconds was a realistic expectation, but that may be highish, again all dependant of the polar alignment accuracy.

A thought is that maybe the All Star Polar Alignment is an electronic form of drift alignment. Best I suggest therefore is set the mount up level, North and at the right Latitude then try the All Star Polar Alignment thing.

Edited by ronin
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Hi, I`ve got a A.V.X and they are good....and to polar align just go into the menu on the handset to polar align,it will almost talk you through it,basically just pick a star roughly south and quite high Regulas is a good choice centre the star the handset will slew to that star,and whatever your out use the dec atl controls to bring that star to the middle of a high power e.p[if possible use a e.p with a crosshair] lock it down and it will ask you to do it again this will refine it a bit then you will get a reading come up and it will tell you how far you are out of polar alignment. DO a couple of stars one in the East,and one in the West if possible and then one south.The higher the magnifcation the better,use a barlow lens as this doubles [or more] the e.p Try and aim for zeros on the readout.....A star sense is good but if your getting one just to polar align it works out a lot.I`ve got a starsense and when I checked my polar alignment it was the same as my polar alignment Des

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I don't do DARV anymore after I read this article -> Drift Alignment
That is the best article of drift alignment in my opinion. Too bad the swf files are dead, specially the Drift Alignment Simulator.
I had messaged the blog owner via facebook to fix it a couple months ago. He said he will, but I think he is too busy. 

Notes:
- Locate a star near the intersection of the meridian and the celestial equator for Azimuth adjustment
- Locate a star that is about 15 - 20 degrees above the Eastern horizon for Altitude adjustment  ((If you can't see the Eastern horizon, the West will do)
- Ignore RA drift, watch only DEC drift
- The mantra is "UP RIGHT"
- If you use dslr, BYEOS/BYNIK will be much easier rather than reticle eyepiece

 

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Well, you are heading into a realm of computer controlled astronomy. So things are going to get a bit more complicated.

Yes, a guide scope is necessary for accurate guiding. Cameras are unforgiving, the record everything, good and bad. So your mount becomes more critical.

I use an AVX myself. It's what I chose with my budget and what I have worked on perfecting. Fortunately many of the programs that work well are free, or come with your choices of equipment. But my AVX wasn't ready for Astrophotography out of the box, not by a long shot. In fact, it was rather poor. I shot a series of images, then made this 6 second video why it stinks out of the box, unguided. You can see how it hunts to stay on target. With the eye, the brain and eye adjusts so fast that this isn't much bother. But the camera tells all.

So you will find yourself with a guide scope and camera, main imaging camera, USB cords, a laptop or other, and a sundry of things. Then programs to use the equipment. I use 6 programs for mine. But I headed down this dark cold path wanting to incorporate my computers into the overall endeavor. I knew it would be a challenging as well as frustrating pastime.

I believe that Guiding should be a part of a Go-To mount. Even if used for basic observing, having a go-to mount staying on the object for hours and hours makes viewing easier, and works good for sharing the view with a group.

If you want to pursue Astrophotography Forrest Tanaka has some excellent videos you should watch. Including one on the AVX.

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  • 11 months later...
On 3/17/2017 at 16:57, JTmunmun said:

I am in the planning stages for astrophotography, aka total beginner, so hoping this doesn't sound stupid. I have a Celestron AVX equatorial mount, which does have the All-Star polar alignment thing, that says it is "accurate enough for short exposure prime focus planetary imaging (a couple of seconds) and short exposure piggyback astroimaging (a couple of minutes)." From what I have read, you kind of have to be able to align on Polaris to be accurate for astrophotography. The problem is that in my backyard, the north is completely blocked by trees. How would I go about getting proper alignment? Is the Celestron Starsense any good or would it even solve the problem? Someone in another thread of mine also said an autoguider is necessary so that is on my list also.

Did you ever get this to polar align in you backyard? I have a similar situation.

Wayne

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Alignmaster is good for polar alignment when you can't see the pole, it uses pairs of stars.  But you do need to have your mount controlled by your laptop for this to work.

Yes it is VERY important to guide for long exposure imaging.

Carole 

 

 

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