Spaced Out

2 hours ago, wimvb said:

To test this, try the following.

Wrap something around the suspected vane and image a star. Repeat with each vane until you find the culprit.

Focus on a bright star (like Deneb in Cygnus), and gradually defocus. Eventually you will see the shadows of the vanes. At that point you can hold a finger near each vane at a time and identify them in the view.

Either of these methods should give you the position of the twisted vane.

Then loosen the screw on the outside of the tube, twist the vane until the diffraction spike looks good, and tighten the screw again. If you tighten as before, this shouldn't throw collimation off. But check collimation of the secondary mirror afterwards anyway.

Easiest way to check collimation is to focus on a bright star, then rock focus in and out. The defocused star should be symmetrical and look the same on inside and outside of focus.

This is brilliant, thank you ! Exactly the info I need to identify and then tackle the dodgy spider vane with some confidence. I've already learnt a bit about collimation and star testing so I understand that bit thanks. 

2 hours ago, MarsG76 said:

The image of Andromeda looks awesome... the split diffraction spikes are very strange indeed... Obviously it is caused by the spider vines. First thing I would do is check to make sure then they're all flat toward the mirror and not twisting at all... any twist will refract light in a strange unpredictable way, especially in long exposures.

Thanks.

All of the spider vanes look pretty straight to me except one that might be just a tiny fraction out but it is really hard to judge by eye, is there a way of determining this without taking photographs of stars through the telescope ?

If I need to twist a spider vane slightly do I adjust by holding it tight and unscrewing the screw on the outside of the tube to loosen then change the vanes position before re-tightening the screw ? If so, will that affect the position of the seconday mirror ? Sorry if these are really daft questions, never touched these before and I don't want to make things any worse !

Hi All

I’m a newby just trying to learn about my telescope and imaging so apologies if this sounds daft.

Attached is my first ever image of Andromeda, it’s 9 frames stacked in DSS taken through a SW 130PDS. I was reasonably happy with this as a first attempt until I noticed split diffraction spikes on the brightest stars. I’ve checked each frame and the split spikes are there, so it isn’t something to do with stacking.

Having googled it and searched on here I am guessing the cause is most likely a twisted spider vane ? It is interesting that the split spike is prominent on one side of the stars only and also only appear to be on the left side of the image, just wondering if this means anything ?

If it is a wonky spider vane, is there a hassle free way to identify which vane and straighten it out ? I only ask because I made the mistake of fiddling with secondary mirror a while ago and it took me days to get things good again !

I’ve looked at the vanes and they look OK, if you squint and use a bit of imagination one of them might be just a tiny bit twisted looking, but I’m not really that confident tbh. Could a twisted spider vane be really difficult to spot and still cause this ?

Thanks in advance for any advice you can offer.

18 hours ago, Adam J said:

If this is your first ever image that is really very very good going.

Thanks very much !

Yeah it was my first attempt. Read up a bit of background beforehand and have done a bit of landscape stylee astrophotography before (milky way etc) so not a complete novice with a camera. However, I am a complete novice with a telescope and mount and DSS software.

Really enjoyed getting this first image, I learnt a lot from it and it has spurred me on to read up more and try to improve at this (and probably get better equipped too)

Some of my landscapey astro stuff is here....

https://www.flickr.com/photos/132427272@N04/

I hope to be adding some more DSO stuff to this soon !

On 31/12/2016 at 15:34, wimvb said:

Great first image. Just keep doing what you are doing, and things will get easier after a while. Once you have the data, you can always reprocess as you learn the software.

To get focus right, I recommend a Bahtinov mask. It's cheap, easy to use and speeds up this part a lot.

For polar alignment you can use the routines in the HEQ5 Pro hand controller (Synscan). Roughly polar align your mount (level, set alt to your latitude and use compass to point az to north)

Then do a 2-star alignment. Use a barlow and a short fl eyepiece for accuracy. Then do the synscan polar alignment routine. (Just watch carefully in what direction the stars move when the mount wanders off.) Then repeat the 2-star alignment. Repeat until satisfied. I find this routine gets me close enough for photography.

Good luck

Thanks for the advice, was thinking about getting a Bahtinov mask next, they seem well recommended.

Still finding my way around the Skyscan bizness, tbh honest I find it harder to align that than polar aligning the mount itself. Just getting the scope locked onto the correct star takes me ages ! Sure it'll come with more practice and learning some more stars.

Next job is to read up more about methods and processing, got a very basic grasp on things, enough to chuck my dslr on there and get some frames, but feel I need to have a much better understanding in order to improve my images.

Hi all

This is the thread that encouraged me to buy a 130 PDS as my first telescope. I used it for the first time a couple of nights ago and this is my first ever image from it.

I had a real hassle setting up because I’m a total newbie and didn’t have a clue what I was doing. Took me hours to polar align my mount but got there in the end, then had hassles getting anywhere near focused, then tried using DSS which has a lot of settings to give you a headache !

Anyway, I got something in the end. It is far from perfect but I am reasonably happy with this as a first time effort, it has given me enough encouragement to start learning more about astrophotography.

Thanks to everyone on here who’s 130 PDS images have inspired me to get involved !

21 hours ago, Adam J said:

And now with some OIII

8 x 900s ISO 1600 OIII - Blue

16 x 600s ISO 800 Ha - Red

Did not bother with any calibration frames.

Posted in imaging section too but I like to share with my fellow 130PDS users

WOW !!