Star testing and collimating 180 Mak - Page 2

Outcast (Carlton) · #21 18-10-2018, 12:38 PM

I will give it a go... but, first some careful reading to try & understand the process & not screw it up completely...

morls (Stephen) · #22 18-10-2018, 02:41 PM

Well, you've convinced me Alex. I'm throwing caution to the wind and getting out the power tools..

Seriously though, you're 100% correct, it's the best way to learn. I'll start with some daylight collimation and hopefully the skies will be clear again soon so I can use the star test to get it spot on.

And the daytime work means I can get to know the layout without fumbling around in the dark.

Thanks
Stephen

TareqPhoto (Tareq) · #23 18-10-2018, 05:38 PM

Right, so my Mak need collimation or tweaking because people say so, you are right, all my results are really not good at all, such as those 2 under poor seeing condition

https://i.postimg.cc/9ccTr3Qj/03-03-16-lapl3-ap193.jpg

https://i.postimg.cc/1sNb2mTd/04-18-00-lapl3-ap172.jpg

I can show planets too, so i don't know how to collimate it to get any better.

Saturnine (Jeff) · #24 18-10-2018, 06:25 PM

Tareq

If your Mak is giving you images that crisp I wouldn't be in a hurry to muck around with the collimation.

TareqPhoto (Tareq) · #25 19-10-2018, 12:22 AM

Quote:

Originally Posted by Saturnine

Tareq

If your Mak is giving you images that crisp I wouldn't be in a hurry to muck around with the collimation.

Those are from my Mak definitely, under poor seeing as i said i didn't process it even much further, so do you really think i should do that because all who got this Mak want to collimate it?

Saturnine (Jeff) · #26 19-10-2018, 12:45 AM

The collimation could possibly be improved but the images suggest that it is good already. Have you performed a star test with it to see if the shadow of the secondary in a defocused star is concentric with the disc of the the defocused star, using a high power eyepiece giving about 300X magnification.
If it is concentric then I would leave well enough alone, for the time being. Use the scope for several months at least, in all seeing conditions , to get a better knowledge of how the scope performs , before fiddling with the collimation.
I used to have a 180 Skywatcher Mak and never needed to adjust it, worked fine straight out of the box, given an hour or so, time to cool to ambient temperatures.
Regret selling it now.

TareqPhoto (Tareq) · #27 19-10-2018, 10:46 AM

Quote:

Originally Posted by Saturnine

The collimation could possibly be improved but the images suggest that it is good already. Have you performed a star test with it to see if the shadow of the secondary in a defocused star is concentric with the disc of the the defocused star, using a high power eyepiece giving about 300X magnification.
If it is concentric then I would leave well enough alone, for the time being. Use the scope for several months at least, in all seeing conditions , to get a better knowledge of how the scope performs , before fiddling with the collimation.
I used to have a 180 Skywatcher Mak and never needed to adjust it, worked fine straight out of the box, given an hour or so, time to cool to ambient temperatures.
Regret selling it now.

For me, better thing is to see images or results from this Mak when not collimated and then collimated for same target in the same night, just to make sure what i am expecting, i really don't know how good or bad even in all conditions, many liked my moon shots, and my planets aren't that bad yet but i am still not satisfied with my planetary results, but i don't that the Mak will be super for the moon and in the same night it is a junk for planets, collimation shouldn't change like this, and then again another nights the moon is still nice in results but planets are just ok or so so, but as you said, i will not tocuh collimation yet.

https://i.postimg.cc/9fRSGq6N/Saturn-27-March-2018.jpg

https://i.postimg.cc/BvVRhmQx/00-02-38-lapl4-ap3.jpg

https://i.postimg.cc/tCkJgMRm/23-23-15-lapl3-ap6.jpg

mental4astro (Alexander) · #28 19-10-2018, 10:56 AM

Tareq,

As Jeff said, the quality of those photos certainly suggests your scope is very well collimated. But a star test is always a good way to shake up the scope to make sure it is performing at its very best. Like I said, you can settle for "good enough", or you may want to make sure that your scope is performing at its very best or if a little tweak is needed.

From your photographs, keep this in mind - there is a very different image scale being used with the Moon and the planets! The Moon shots look sharper because the image scale is small. The planets are softer because there is a lot more magnification being used. This can make things very misleading unless you are comparing images ALL at the same scale, otherwise it is a useless comparison.

Certainly don't collimate just because "people say so". YOU need to check things out for yourself, and ONLY act if you see a need to improve things. And if you find out that there is no more room for improvement with the collimation of your scope, then don't touch the blooming thing!

And star testing really needs to be done under good seeing conditions. Especially when really pushing the scope to its very, very best. You really do need steady seeing in order to be sure of the star figure the scope is throwing up, and any shimmering, boiling movement is not helpful.

A star test is what will tell you if you do need to tweak the collimation or not. Not me or anyone else

Alex.

TareqPhoto (Tareq) · #29 19-10-2018, 01:06 PM

Just wanted to say that i am very happy with this Mak for the moon only, but not for planetary, because of scaling, but this is no surprise, most big names are using large scopes anyway to sampling for planets, so i won't just use this Mak for everything for ever.

I did a test video on a star, focus out in both directions, and people told me that it is fine, so i just stopped there and didn't bother with collimation as long it is fine.

morls (Stephen) · #30 21-10-2018, 10:14 PM

Today I collimated the scope, first with naked eye/daylight and then a fine-tune with a star. It's made a real difference, and I'm very happy. It was not difficult at all, I just took my time and adjusted one screw at a time so I could see what was happening.

I noticed that the locking nuts weren't very tight at all when I started, and that care needs to be taken when tightening them after collimation. I did this at 338x magnification, and got them nice and snug. The image shift has reduced considerably, and the focus is much more positive.

Thanks everyone for your input. There's been a significant improvement already, and I'm sure I'll get better at it with practice.

Cheers

Stephen