From 130p to 130pds…the hard way.

[chemistorge]

Hi, Around 2 years ago I got fed up with having a scope with a horrible plastic focuser but good optics….namely the sky watcher 130p. I had managed to score a Crawford focuser from Astro buy and sell which I intended to fit. As I only had the one scope it took me a while to gather the courage to perform open heart surgery on my one and only scope!

Here is my journey:
 

First I found a website (Here) to calculate the intersection size between the tube and focuser to get a cut out template. This was stuck on the tube 90 degrees around and 30 mm closer than the original focuser hole.

I then used a 3 mm drill bit to drill a “dotted line”.

I then used a hand held fine jigsaw blade to join the dots.

To smooth cut out to the line I used a grinding disk on a drill to go round the hole until it was perfect, after which I drilled the relevant mounting holes. The focuser and spider locations were 30 mm closer to the primary mirror than previous which has allowed prime focus with easy.

 

I have been using the scope for the last 2 years with no problems at all. Just after I finished this project I noticed that Skywatcher had started doing  the 130pds (duh!, but it was more fun DIY!).

Edited July 22, 2021 by chemistorge

[Tan Zhi Qi]

Wow, amazing job! What do you think about the new focuser? I'm about to get the 130pds soon. 

[chemistorge]

The Dual speed focuser is very good, completely rock solid. I have a motor attached for auto focus and it work great. It was the best up grade to my scope.

[Marvin Jenkins]

Hi chemistorge, I went mad with an Orion ST130 which is a bit like a 130P.

I did the same as you and bought the 2inch DS focuser as I hated the little plastic thing it came with.

I had a hankering for attaching a DSLR and thought the PDS focuser would solve the problem but there was not enough back focus.

I had to move the main mirror quite a way up the tube towards the secondary and now it is a real hassle to collimate.

The thread is on here somewhere, with extras like flock and blackened mirror edges.

Thanks you for the reminder that I need to give it a bit more work and get it right. The problem was a 150pds turned up and that grabbed all my attention.

Good luck with the project, keep up the hard work.

Marvin

Edited July 22, 2021 by Marvin Jenkins
Typo

[chemistorge]

Hi Marvin, Did you also move the focuser and spider down the tube? I moved mine 3 cm down which solved all the back focus issues for prime focus without moving mirror.

[Marvin Jenkins]

Now you say this I am wondering why I did not move the focuser and spider down the tube🙈

I saw so many threads saying the primary needed to be moved further up the tube I didn’t look at the problem from the other direction.

I will say however, that my comment about collimating is about how hard it is to get accurate optics in fast scopes. I am sure that fast F scopes at the expensive end of the market have adjustments that can be fine tuned. A 130p is a bit more basic, so one tiny adjustment here or there may not give you the desired effect you are looking for.

Good luck anyway and will give my odd ball Orion 130st PDS another look.

Marv