130 PDS issues

[matt_baker298]

This scope has served me very well but ever since I've acquired my 1600MM + filter wheel, it's been causing me a lot of trouble regarding tilt and bad stars. 

I tried to get around this by purchasing this item which claims to reduce the tilt, which it does, only very marginally compared to just three thumb screws. In the description of the item, it stated that it can be rotated with a counter ring. Although this does work, it doesn't hold it tightly enough and causes even more tilt than there already was, and again, probably something to do with the weight as I was very easily able to move the camera up and down.

I have three options to amend my situation.

1. I can try to think of something else to completely reduce the tilt enough for it to be acceptable. I was thinking of a baader clicklock but I've heard it doesn't work on the stock SW focuser

2. I buy a Moonlite CR2 focuser. Only issue I'm not sure about is the added weight of the focuser + the camera and filter wheel means that I won't be able to balance properly due to the focuser hitting the tube rings of the scope

3. I upgrade and buy something like an Esprit 80ED.

Saying this, I really do like the 130PDS. It's fast, has wide aperture and a decent focal length for a dirt cheap price. I also appreciate the challenges that comes with a newtonian and the rewards it reaps if everything goes right.

The item I tried: https://www.teleskop-express.de/shop/product_info.php/info/p5417_Lacerta-Thread-Adapter-for-using--Baader-MPCC-with-Skywatcher-Newtonians.html

[+RonC]

Hi Matt, I have a 150 PDS not a lot different. That adaptor should work fine i would have thought, but with a CC, filter wheel and cam on that's a lot of weight to carry!

I have been using mine (cc, filter drawer and cam) with the focuser at the bottom so there's no sideways weight issue, it seems to work OK for me using the 3 screw

SW focuser. I'm using an ED80 at the moment and have a Moonlite focuser on which is very stable with no determinable movement that I've seen.

Not sure if this helps but give it a try. (I have a tube rotator system to turn the OTA).

Cheers

Ron

[Clive]

This may be a daft question, but do you know what's actually causing the telescope image plane not to be parallel with the camera sensor plane?

[matt_baker298]

Just now, Clive said:

This may be a daft question, but do you know what's actually causing the telescope image plane not to be parallel with the camera sensor plane?

I would assume it being the sag caused by the tilt in the focuser due to the weight of the camera + filter wheel

 

7 minutes ago, RonC said:

Hi Matt, I have a 150 PDS not a lot different. That adaptor should work fine i would have thought, but with a CC, filter wheel and cam on that's a lot of weight to carry!

I have been using mine (cc, filter drawer and cam) with the focuser at the bottom so there's no sideways weight issue, it seems to work OK for me using the 3 screw

SW focuser. I'm using an ED80 at the moment and have a Moonlite focuser on which is very stable with no determinable movement that I've seen.

Not sure if this helps but give it a try. (I have a tube rotator system to turn the OTA).

Cheers

Ron

It's not that the adaptor doesn't work, more to the fact that the rotating ring can''t handle the weight and hold the whole thing flush. I'll do some thinking and poking around to try and figure out a solution without spending more money

[philjay]

Tilt can be caused by a number of things, focuser adjustment  clamping arrangements etc but if your are hanging a heavy imaging rig off the side of an ali tubed newt then flex in the actual tube around the focuser base is something to look out for, e.g. tube distortion. The focuser is held on with 4 screws. Sometimes there is a plate on the inside which takes some of the flex out but if youve covered all the other tilt sources it might be worth reinforcing this area with an internal spreader plate.