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How to align prior to imaging?


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Hi,

First night out yesterday to try imaging with new scope and mount.

Was pretty pleased overall, but had difficulty getting aligned.  Using Cartes-de-ciel  and EQMOD to guide the mount, but with a Canon DSLR attached had great difficulty 'seeing' what I was aiming at. Liveview screen was impossible to see stars on, and very time consuming to keep taking a photo and studying it.

Do most folks get set up with an eyepiece so you can see what's what before attaching the camera, or do you all have the luxuary of a permanent set up which doesn't get moved from one session to the next?

Any help to get to a point where I can set up and image in less time would be appreciated.

Thanks

Chris

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I align a similar set-up by taking a few pictures, I do have the camera controlled from the laptop.  EQMOD with a three star alignment should put your target in the center of the frame - for a final tweak, if I think it is required, I set the ISO rate to the highest (I'm not concerned about quality here) and take maybe a 15 sec exposure (RAW and JPEG setting - its far quicker to open a JPEG for a quick look).  Adjust and take another frame.  It seldom takes more than a minute or two to set the framing exactly the way I want it.

Another trick is to download and set up all the star catalogues available with CdC - down to about mag 16 or so.  With these installed it is very rarely that you cannot find a suitable star to slew to to get the final adjustments to the framing that you may need.

EDIT - or use a plate solver like Astro-tortilla or Elbrus - Thanks Martin!

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I found that live view doesnt work unless you have your picture settings on bulb mode and a high ISO. I can get away with centering the star in the middle of the screen and that works well enough for me.

I still havnt gotten around to getting EQMOD sorted out properly, so I do it via the handset.

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Hi,

I use Astro Torillia once I'm close - how far out can it cope with being?

My issue, at least last night, was getting it to point anywhere close to the correct place and not being able to see where it was pointing was a pain - too used to visual I guess.

Is the consensus that an eyepiece is jusu not used, and everything is done via the camera and it's screen and / or the laptop? What if there is no laptop, such as working as a remote dark site and just using the scope and DSLR - how easy is it to get aligned then?

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How close are the finderscope and the main scope aligned? You need to get the star in the center of the highest eyepiece you can, then align the finder. When you put the camera on, you can then use the finder to center the star and you should be pretty close. Sometimes I am off, so I slew about a bit until I see something fly across the screen!

Not too sure about a dark site, I guess you could just use the screen, but that would be awkward on some stars!

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It can be a real pain! Some nights it works well and others, it's pants!

  • I polar align as accurately as possible
  • Do a 2 star align with a wide-ish-angle EP (24mm) and centre as as well as poss (using a higher EP to finish will help)
  • Use a well-aligned red dot finder to help centre, if necessary
  • On second star I attach camera and focus, on 10x zoom on live view, with a B mask
  • Slew to object and, as Roger says, push the ISO right up and take test shots
  • If still not on target, use the RDF to help if there are recognisable stars nearby
  • Failing that, I park scope and do the star align again
  • When on target, to frame, I use the handset on a slow rate, hold down one arrow for about 3s to see where it's going! Then position.

+1 for a plate solver though I've never used one!

Alexxx

Edited by Astrosurf
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I always align using EP and then attach DSLR. Works for me.

Peter

me too.

I just do a simple 2-star align with the eyepiece, then go to a bright star near my intended target and once centered on that, do a pointing-accuracy on that, then go to target.  I've never really found the need to plate-solve to be honest. 

I have done the star-align through the DSLR viewfinder before when I've been too lazy to take it out and refocus it, but it's much harder and probably not worth the effort.

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I've not put an EP in my 'scope for younks. My mount is always in the garden, covered by a telegizmos 365 cover so I only have to set the scopes on. I use a RDF if I cannot see an image in AA5. ATM I'm only doing a 1 star align / sync in CdC but I choose a bright star near to where I want to image. ATM I'm using Betelgeuse for both M42 and Rosette.

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After my polar alignement procedure i set the scope to home postion which i defined as RA 0°/ DEC 90°. Often when in Homeposition i`m a little bit off in DEC (because obviously polar alignment is always a bit different). In this case i release the DEC clutch and then turn the scope slightly to have Polaris in my camera field of view (ca. 1.3° across). From that new position i define a coordinate system with CdC and usually the first alignment star is in the camera frame, the second one is close to the middle of the camera frame and already the third one is pretty much in the center. In the rare case that the first alignement star is not in the frame, i can use my guiding cam (which has wider fov) to get it right. This procedure works very repoducably for me. Never tried out AT, but it sounds interesting.

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I do a 2 star alignment and then PA using the synscan handset and 25mm eyepiece. I then use the goto to slew to the target and do some quick subs to check I'm on target.

Just downloaded AAv5 and got the plate solving working in simulator mode, yet to use it in the field

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On a related question, if I may.  

I also generally use SynScan to x2 star align and then polar align which, as I don't have a view of Polaris etc, works quite well.  What polar alignment MEL and MAZ readings is achieved and found to work by others?  Obviously 00 00 00 would be nice but failing that, what's a decent number with which to image?

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  • 2 weeks later...

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