Imaging with the 130pds

[Adam J]

On 09/03/2020 at 18:13, Spaced Out said:

Well after a weekend of research it seems there is not an easy solution to my focuser sag problem on the 130PDS. There are just 2 focusers that will fit it seems ? The Baader SteelTrack Diamond (my preferred option) won't fit.

Moonlite - It'll fit but it costs ££££££ especially if adding autofocusing, while reviews seem mainly favourable a couple of people have said it’s no good. 

TS-Optics MONORAIL 2" Newtonian focuser with Micro Transmission – it’s cheaper but fiddly to fit (drilling holes), can’t find any reviews but the spec seems to suggest it’ll be better for my purposes than the stock focuser.

I’m waiting for a reply from TS optics as to whether this one will fit too.

https://www.teleskop-express.de/shop/product_info.php/info/p6522

Tbh, I am starting to wonder whether I should move to a new telescope with a better focuser rather than faffing about trying to fit one into the 130PDS. I’ve been looking at TS optics 6” f4 Newts which have the same two TS focusers mentioned above, trouble is I don’t know how good these focusers are !

The TS Newtonians are good scopes but to be hones F4 Newtonians are fiddly things that I would avoid personally. I would just go with the F5 and stick at that or you end up swapping a focuser issue for colimation troubles. 

[Spaced Out]

2 minutes ago, Stub Mandrel said:

When you say 'it slips on the spindle' do you mean:

The spindle turns but the focuser tube doesn't move.

The autofocuser turns but the spindle doesn't rotate and the tube doesn't move.

The autofocuser doesn't turn and the stepper 'skips' steps?

If the second of these the universal joint between stepper and spindle needs to be tightened up.

 

The autofocuser turns but the spindle doesn't rotate and the tube doesn't move.

The SW autofocuser is tight on the spindle but it slips when the focuser tube is tensioned up, result is the knurled silver bit turns but the spindle does not turn. I guess this is supposed to happen when the tube reaches it's limit of travel and stops. If I loosen off the tension a little it turns ok.

[Spaced Out]

1 minute ago, Adam J said:

The TS Newtonians are good scopes but to be hones F4 Newtonians are fiddly things that I would avoid personally. I would just go with the F5 and stick at that or you end up swapping a focuser issue for colimation troubles. 

Sir, you are a mind reader ! Thanks, this is exactly what I was thinking about just now, I've read a lot online about f4 and collimation woes. This was going to be one of my next questions about TS optics newts. 

I may try a new autofocuser first and see if I can tension things up a little bit better. If that doesn't work then I guess I can still use it on a different scope once I've saved up the £.  

[mAnKiNd]

I've had the ZWO EAF on the 130PDS for about three months now and never needed to modify anything, I've been very happy with its consisten performance. I did own a Pegasus Focuscube before on a refractor, and I find that the EAF, even with half the stepper resolution of the Focuscube, still performs very well at a lower pricepoint.

[Adam J]

1 hour ago, mAnKiNd said:

I've had the ZWO EAF on the 130PDS for about three months now and never needed to modify anything, I've been very happy with its consisten performance. I did own a Pegasus Focuscube before on a refractor, and I find that the EAF, even with half the stepper resolution of the Focuscube, still performs very well at a lower pricepoint.

ok its just the focus cube that has issues with the 130PDS then, to be honest though none of these work with every scope on the market, you just cant account for all the variations. 

[Stub Mandrel]

2 hours ago, Adam J said:

I would warn you that for any of those models (I used the focuscube) you will need to modify the 130PDS focuser to allow connection as the body of the auto focuser interferes with the spider vane thumb screw. You need to cut down the pin and mount the auto focuser upside down. I got that model in the knowledge that I was going to be moving it over to the esprit 100. But to be honest for the 130PDS this is best unless you are willing to modify your focuser. 

https://www.firstlightoptics.com/astronomy-cables-leads-accessories/primaluce-lab-sesto-senso-v2-robotic-stepper-focus-motor.html

Adam

Or just flip the focuser spindle assembly 180 degrees, this also puts the focuser nearer the c-of-g of the mount.

[Whistlin Bob]

I'm curious that the SW auto focuser is causing problems. I'm using it with an ASI1600 & EFW on the single speed focuser you get with a 200p and it does a fine job. The focuser is pretty old so I've had to tension and line it up pretty carefully, but the AF seems to work fine.

If you can hang on a few days I'm planning to try and mount a SW low profile focuser that I've acquired on my 130pds, I'll let you know if the tube size really is a restriction.

[lnlarxg]

4 minutes ago, Whistlin Bob said:

I'm curious that the SW auto focuser is causing problems. I'm using it with an ASI1600 & EFW on the single speed focuser you get with a 200p and it does a fine job. The focuser is pretty old so I've had to tension and line it up pretty carefully, but the AF seems to work fine.

If you can hang on a few days I'm planning to try and mount a SW low profile focuser that I've acquired on my 130pds, I'll let you know if the tube size really is a restriction.

I have the SW low profile focuser and that definitely doesn’t fit the 130pds. The focuser plate is too flat, on a 130pds it looks like a plank on a see-saw. Well... unless you DIY some adapter plate

[Spaced Out]

53 minutes ago, Whistlin Bob said:

I'm curious that the SW auto focuser is causing problems. I'm using it with an ASI1600 & EFW on the single speed focuser you get with a 200p and it does a fine job. The focuser is pretty old so I've had to tension and line it up pretty carefully, but the AF seems to work fine.

For me the SW autofocuser sort of works to move the ASI 1600 + 8 pos FW + OAG + MPCC, the focuser tensioning seems critical tho. Whether my sag/tilt issue is because of this I'm not really sure. I'm just guessing that because the focuser isn't tensioned too tightly (because it causes the autofocuser to slip on the spindle) the tube may be moving just very slightly when I put the camera on. Either that or the focuser is just not built to take all of the weight and the tube is going to move anyway ? Either way I am getting tilted images when I hang this heavy stuff off there. 😕

I think my next step is to remove the autofocuser and add more tension to the focuser to see if that helps.

Edited March 11, 2020 by Spaced Out

[Spaced Out]

🤔

Edited March 11, 2020 by Spaced Out

[mAnKiNd]

Fwiw, I've used different filter wheels over the years with different scopes for different strokes, and currently I'm decided that they're not worth the negatives (weight, downtime during changes, refocusing etc..). I screw a single filter right in front of the camera and thats my session for the night. Next session, I use another filter. I've found this is a much easier, efficient and ultimately more productive workflow for me. Ymmv

[wimvb]

39 minutes ago, Spaced Out said:

I think my next step is to remove the autofocuser and add more tension to the focuser to see if that helps

Be careful with that. At least on the 150pds, which has a similar focuser, it's possible to tighten the focuser so much that you start bending the spindle.

[Adam J]

2 hours ago, Stub Mandrel said:

Or just flip the focuser spindle assembly 180 degrees, this also puts the focuser nearer the c-of-g of the mount.

Won't work gets in the way of the tube rings. 

[Whistlin Bob]

3 hours ago, lnlarxg said:

on a 130pds it looks like a plank on a see-saw

Yep! Whilst you were typing that I was experiencing a sudden burst of enthusiasm and doing a bit of fitting. I can confirm you're absolutely right! 

[Stub Mandrel]

 

11 hours ago, Adam J said:

Won't work gets in the way of the tube rings. 

Not on my scope.

Depends where you have the tube rings!

 

[Adam J]

2 hours ago, Stub Mandrel said:

 

Not on my scope.

Depends where you have the tube rings!

 

When using a heavy camera and with the additional weight of the auto focuser you are forced to place the rings as far forward as possible, the 130PDS already suffers from being nose heavy. 

[Stub Mandrel]

2 hours ago, Adam J said:

When using a heavy camera and with the additional weight of the auto focuser you are forced to place the rings as far forward as possible, the 130PDS already suffers from being nose heavy. 

It's still possible OK as I just attach the dovetail to the mount near the front ring (best position for me is with about 1" between the stop screws and the cl;amp on the mount) . A small amount of nose-heaviness helps limit dec backlash.

Edited March 12, 2020 by Stub Mandrel

[matt_baker]

How well will a Canon 60D and a MPCC MkIII hold up with the stock focuser? I reckon it'll weigh about a kilo in total

[Spaced Out]

31 minutes ago, matt_baker said:

How well will a Canon 60D and a MPCC MkIII hold up with the stock focuser? I reckon it'll weigh about a kilo in total

I've used MPCC with Canon 6Dmk1 and 7Dmk2 and OAGs no problems. Only when I introduced a mono camera and heavy filter wheel did I see tilt/sag. 

[matt_baker]

Okay, thanks 👍

[Spaced Out]

For anyone who’s interested here is an update on my 130 PDS focuser sag/tilt issue.

I suspected the SW autofocuser was the weak link in my gear so I removed it. Then I tensioned the focuser quite a bit to try and tighten everything up. The result is quite an improvement, the obvious tilt along one edge of my images is now gone (or almost gone).

I’m looking for a replacement focus motor and need something that will still turn the now well tensioned focuser (my old SW motor would just slip). I’m concerned that if I have to loosen the tension on the focuser again then the sag/tilt will return.

I also have another little issue with star shape now, see here:

https://stargazerslounge.com/topic/349920-what-do-people-think-of-these-stars/

It’s not as bad as the tilt thing but once I’ve noticed ’eggy’ stars I find it difficult to un-notice them !

[Stub Mandrel]

Originally intended for 'show us your setup at night'... I've stretched this image 🙂 and it shows what I'm hanging off the 130PDS stock focuser.

 

Edited March 20, 2020 by Stub Mandrel

[Uranium235]

Lockdown astrophotograhy

 

About 3 hours in 4min subs with the ASI178 Cool

[OllieN]

Also on lockdown last night and first go at a smaller galaxy. 

27x4min with the Nikon D5500

 

[Shaun_Astro]

Amazing, several clear nights all at once!

NGC 2903. Unfortunately a very small target for the 130pds. 9.5 hours of 180". Unmodded 1300d, ISO 800.

 

 

 

Edited March 25, 2020 by Shaun_Astro