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 !

Thanks, that wasn't really a target, it was just overhead for a quick test shot. Trouble is, once I notice un-round stars it really bugs me ! I want to try and get them as good as possible 🤔. Can stacking improve the shape then ?

Yes of course ! Sorry, I meant 0.5mm and 0.7mm. I've amended the original post 👍

Hi All I've been wrestling with tilt when using a heavy mono camera and filter wheel on my stock Skywatcher 130PDS focuser. After a lot of trail, error and faffing I have managed to eliminate the worst of the tilt by removing the flaky SW autofocus motor and adding more tension to the focuser. Having done this and mucked about with things in the process I could see what appeared to be a little coma in all corners radiating inwards. I played about with various spacers for a couple of hours to get it as good as I could. By 1am my little brain was tired and I couldn’t fathom things out anymore so I packed up. This single test shot shows how things looked when I left it. At the time it seemed like if I added 0.5mm things got worse and if I removed 0.7mm things got worse. However, by this point I was just seeing stars everywhere I looked ! So, I’m just wondering what people think of the stars around the edges/corners ? To my eye they look a little 'eggy' in places. Does it need more spacing ? Is it overspaced ? Is there still an element of tilt going on here ? Thanks

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.

Thanks. I emailed TS optics last week about that base and that focuser (it looks interesting). Only drawback is that it involves re-drilling the tube to fit it and they told me....... "It will not fit perfectly, it's a little wider, but there are no other possibilities. the curvature ratio will not correspond, but it's possible to fix it, even if it will not be a " aesthetic perfect" result" It's something I would have considered but sounds like I would have to bodge it and I'm a bit nervous about cocking it up, I'm guessing it'll need precision placement...... Which brings me back to the Moonlite. 🤔

Thanks. Agree about the cost, they are supposed to be top notch aren't they ? Couldn't find a base to fit the 130 PDS tho..... even if I could, it seems a bit crazy to spend that kind of money on a scope that only costs £160 !

Thanks. I'm not liking the sound of 'slippage', do you mean the draw tube was actually slipping or was it sagging/tilting with the weight ? Was that with heavy gear ?

If I could I'd fit a Baader SteelTrack Diamond but Moonlite is the only option I have for the little 130 PDS. 😐

Thanks mate, that's encouraging to hear. I'm guessing your imaging kit is heavy too (filter wheel etc) ? Perhaps I am being too cautious about Moonlite ?

We have some new downward directed LED streetlights about 25m away. They aren’t too bad but they are sort of facing away and only one is properly in a direct line of sight, the telescope is shielded from the others by fences and buildings. When they first appeared I was really shocked (because it used to be a dark village road), I was considering erecting screens to block the light but in the end I just added a DIY flocked dewshield to my reflector and it seems not too bad. I haven't ruled out making a screen or two but I don't feel it is an urgent requirement. Our streetlights also dim by 50% after midnight. I think I might have more problems if there were more lights in direct line of sight, a bit closer and facing towards us. I would guess that the height of the lights also has an influence too, lower the better ?

Why is that ? Whatever route I take I will definitely require a good focus motor.

Yeah, I guess but when one person says they are complete rubbish and another says they're not much better than stock focusers for tilt issues/holding heavy gear it makes me wonder if it is suitable for my needs. Of course, I could be being overcautious and they might be great !

Thanks. I already have a long dovetail fitted. The focuser + flaky SW autofucuser seems to be the issue for me, it doesn't like it when I hang heavy gear off it. I’m still not sure about the Moonlite, lots of people rave about them but at least a couple on here have said they’re not great. It’s a lot of money to spend so I’d like a little reassurance that it will help solve my issues. 🤔

Thanks, I've looked into fitting Baader SteelTrack etc. The only focuser that will fit the tube diameter EASILY is a Moonlite (it has a specific 130PDS fitting kit), they're expensive and I've seen mixed reviews so I am little nervous of taking that route. Seems all other focusers will require some amount of bodging !

Yep this is my concern, I want an easy life ! I'd rather spend my time imaging than faffing on with collimation all the time.

This is my thinking too. Moving it about after every session is surely going to be a pain in the neck with an f4 ? So long as I handle it gently the 130PDS is quite forgiving, I can just remove the scope with camera still attached then bring it back a few days later and it holds collimation well.

I'm used to the 130PDS newt which I really like when the focuser isn't sagging. I also like diffraction spikes ! I did look at the SW Esprit 100 ED for a little while. It's a lot of ££££ for me and looking online my camera (ASI 1600) seems to have more noticeable micro-lensing issues with refractors and bright stars, which puts me off a bit too.

All my research so far has been online. While some people suggest collimation of f4 is no harder than f5, a lot of folk seem to suggest it is more demanding and also f4 telescopes don't maintain collimation very well compared to f5. My concern is that the telescope won't be permanently mounted in an obs, it will be moved by hand indoors after every session, I might spend more time worrying about collimation and less time using it ! Collimation is the only thing putting me off an f4 scope tbh.

Thanks, I'm looking for an off the shelf solution really that I can use for imaging. Also I've just ply lined my little shed for a warm room and I'm sick of ply !

Thanks, I am coming from a SW 130 PDS. It's a nice scope but its weak point is the focuser, it works OK with my DSLR but it doesn't like my heavy camera + filter wheel + OAG + MPCC combo, this is why I'd like to upgrade to a carbon tube and better focuser if possible.

Just wondering if anyone has ever used a Sigma 500mm f4.5 HSM for astrophotography ? If so is it any good ? I have and old beat up version that I use for birds and wildlife, it’s a great lens for that and very sharp when you stop it down to F8. I'm considering getting some bits to try and chuck it on the mount.

Does anyone know if this exists ? I would like to find a small f5 newtonian with a 600mm(ish) focal length, carbon tube and a decent focuser (or ability to add a decent focuser) ? I’ve seen the TS optics scopes, they look good but the smallest f5 version is 750mm FL, I’d prefer a little less. I would consider the f4 600mm version but the internet is littered with stories about collimation woes below f5.

🤔

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.