Is this good collimation for AP - star test

[Vulisha]

Hi

I tried to capture mars/planets and some dso, but I am always blurry despite Bathinov saying it is in focus, so I did star test and it seemed a bit off and i recolimated and then did star test bellow, but it is still blurry. There is intra and extra focal images. Intra focal seems fine but extra seems still bit off, if I try to set it,  then intra goes bad. Scope is Heritage 130p

Edited September 13, 2020 by Vulisha

[inFINNity Deck]

Hi Vulisha,

if you flip the right half of both images you can tell that both are quite off, although the first is slightly better. The scope could do with collimation.

What kind of scope is this and why does it have this single blockage?

Nicolàs

 

[Vulisha]

Oooh thats the trick I did not know! Flip It

I have laser collimator but I believe it is not good as it says collimation is fine.

Ok, and any idea why is extra so different than intra? Could it be due to tube flex? 

[inFINNity Deck]

What kind of telescope is it?

Nicolàs

[alacant]

Hi

Best to avoid laser collimators.

One time job: centre the secondary using a Cheshire eyepiece. One with cross hairs makes life easier. It's then just a case of a quick tweak of the primary now and the. 

Have a look here.

HTH

[Vulisha]

1 hour ago, inFINNity Deck said:

What kind of telescope is it?

Nicolàs

If is flextube newtonian. 

1 hour ago, alacant said:

Hi

Best to avoid laser collimators.

One time job: centre the secondary using a Cheshire eyepiece. One with cross hairs makes life easier. It's then just a case of a quick tweak of the primary now and the. 

Have a look here.

HTH

Oh I do not have Cheshire, I used only collimation cap. Will have to buy one then. Thanks on the tip! I will mesure my secondary but visually it looks fine. 

[Vulisha]

Ok I redid colimation and now on extrafocus I get nearly perfect result but Intrafocus is garbage but all in all better than it was... I believe without fixing this single spider stick, I won't be able to create better focus than this one. 

@inFINNity Deck 

It is flextube newtonian Skywatcher Heritage 130P and it really has only one spider. It is good because I can retract it and then I have prime focus on DSLR, but secondary holder is bad and focuser is complete garbage. I saw skywatcher made 150p version of this one, but unfortunately kept this bad focuser but at least they put tree way secondary holder now.  

Edited September 14, 2020 by Vulisha

[inFINNity Deck]

Hi Vulisha,

I am not familiar with this type of Newton. I should have mentioned that for testing the donut, it should be mirrored in two perpendicular directions:

So although the first image looked right along your initial mirror-line, in the direction perpendicular to that it is still far off. The second image is near to perfect in that direction, just as the first image in the initial mirrored direction. This on itself is very strange and can not be easily explained other than by flexure in the optical system.

Could it be that the secondary holder can rotate/flex along its length?

Nicolàs

 

[alacant]

Mmm. Is this the telescope?

I'm wondering if it will hold a dslr without either distorting the extension rods or the eyepiece support...

The good news is that it looks to have adjustment to be able to place the secondary nearer or further away from the eyepiece. I think this is one of the adjustments you're missing.

HTH

 

Edited September 15, 2020 by alacant

[Vulisha]

Yes, that is that telescope, it will not hold DSLR but small mirrorless eos m camera with aps-c sensor, 250g weight. 

 

I mesured it and on both axis distances are 61mm-59mm so it is misaligned by 1mm on each axis, I might be able to align it on holder axis, but problem is that it is spinning so it could be very very hard to extend it, other side is bending and that is adjustable by bending holder a bit.  Could this be due that 1mm missaligment? 

Maybe if I buy PVC pipe, focuser and secondary holder to create custom non flextube?

Anyone knows where can I buy spider(maybe even secondary 25mm for this one? ) for 130 telescope? Failed to find it on aliex, found only for 114/150/200 scopes. 

Scope has really good primary but rest of construction is bad except flextube 

[Pixies]

Bear in mind that the star test will only work accurately if the star is central in the view. If the star is off-centre, the shadow you are seeing will not be concentric.

I'd also suggest that the image is too far out of focus. You are seeing the shadow of the secondary (and vane), not the Airey disk and diffraction rings. What magnification are you using? It should be very high.

https://garyseronik.com/no-tools-telescope-collimation/

Edited September 15, 2020 by Pixies

[alacant]

1 hour ago, Vulisha said:

Anyone knows where can I buy spider(

Hi

It maybe cheaper to get a ready built solid tube 130;)

[Greg Shaw]

20 hours ago, Pixies said:

Bear in mind that the star test will only work accurately if the star is central in the view. If the star is off-centre, the shadow you are seeing will not be concentric.

I'd also suggest that the image is too far out of focus. You are seeing the shadow of the secondary (and vane), not the Airey disk and diffraction rings. What magnification are you using? It should be very high.

https://garyseronik.com/no-tools-telescope-collimation/

This sounds great, This is the first time I have seen this way of correcting with an out of focused star.

I have been doing the old approach of adjusting (guessing) and them moving the star back to the centre to see if it made a difference.

I will definitely give this a go. I was wondering is it recommended to always use an eyepiece or can I use my camera zoomed in?

Edited September 16, 2020 by Greg Shaw

[Pixies]

20 hours ago, Vulisha said:

Anyone knows where can I buy spider

Try https://www.astroboot.co.uk/AstroBoot

[Vulisha]

21 hours ago, Pixies said:

Bear in mind that the star test will only work accurately if the star is central in the view. If the star is off-centre, the shadow you are seeing will not be concentric.

I'd also suggest that the image is too far out of focus. You are seeing the shadow of the secondary (and vane), not the Airey disk and diffraction rings. What magnification are you using? It should be very high.

https://garyseronik.com/no-tools-telescope-collimation/

I am using cameras, EOS M and Logitech C270, as I don't see problems visually. Thanks on that link! While I did keep star in the center I did that due to FOV as I am also a little OCD. I did not know it affects colimation. Thanks!

20 hours ago, alacant said:

Hi

It maybe cheaper to get a ready built solid tube 130;)

Not in my country, 130p is around 250 gbp  and try explaining it to my wife... 

 

1 hour ago, Pixies said:

Try https://www.astroboot.co.uk/AstroBoot

Thanks on the link, I found the item but shipping is 4x item price :O. I asked them is that a mistake, hopefully it is!

[happy-kat]

There are a lot of tiny screw adjusters on the telescope, I think take your time, Polaris is good to use, and don't use that laser. I've only got a cap, I used a ruler and paper to ascertain I had an ok secondary mirror and Al's collimation aid program.

[Vulisha]

I think I nailed it now! it was not an easy work but I managed by adding washers, distancers, bending holder a bit and colimating a few days. 

Edited October 16, 2020 by Vulisha

[inFINNity Deck]

Hi Vulisha,

as far as I can tell from the tiny scale, this result indeed looks pretty good. I have mirrored your image along two axis:

It seems pretty symmetrical in both directions, so well done! Does it also make a marked difference when observing?

Nicolàs

[Vulisha]

Thanks Infinity/Nicolàs! It could use a bit more fine tuning but it is pretty well now. Also what software do you use to split image I struggle with Photoshop. 

I have managed to see dark spot on Mars, untill now it was just a blurry glowy ball, and seeing is disaster these days. I did try to image Mars as well but my camera somehow corrupted 2/3 4gig raw video files so I did not get any results

 

Toll that was much of help was Al Coli Aid:

https://stargazerslounge.com/topic/232508-collimation-help/

It is available here on forum for download.

I used simple colimation cap, phone holder, and my phone with DroidCam app. Nothing else. 

I made big circle to match colimation cap hole, small circle to match secondary and + to match primary middle mark. 

It helped a lot to be able to work and see results on monitor directly. 

Edited October 16, 2020 by Vulisha

[happy-kat]

Glad you persevered and have got your heritage working well and getting great observing