Bad Image from Newtonian

[Nikolas (Nik)]

Originally Posted by Ramius

Crossed my mind but what would do the job? I don't know that the Skywatcher / GSO crayfords would necessarily be an upgrade and Feather Touch isn't happening.

Irrespective need to run a full nights imaging before deciding what's next - and weather looks bad for a week.

Rack and pinion type maybe

[Startrek (Martin)]

I use GSO standard Crayford dual speed focusers which have load rating of 2.5kg and 30mm of travel however the heavy duty linear mono rail is significantly better.

The GSO heavy duty linear crayford with monorail which has a load rating of up 4kg and 50mm of travel GSO ( see attached TS rebadged GSO ) these are guaranteed not to cause tilt.
I have one of these as a spare for my 8” Carbon Newt

https://www.teleskop-express.de/en/t...ual-speed-3700

I’ve previously had a Sky-Watcher scope and have had my 12” SW Goto Dob for 6 years now. The barrel and thumbscrews on this dual speed focuser is rubbish for imaging , very flakey.

For the cost GSO are pretty good focusers
I did have to make up my own custom bracket to suit the ZWO EAF on the 8” and 10” carbon newts.

TS now make a 3D printed custom bracket for their GSO rebranded focusers to suit the ZWO EAF

https://www.teleskop-express.de/en/t...focusers-13279

Cheers
Martin

[Ramius (Bill)]

CYCK is rack and pinion !
Have been reading an old thread here and some good info - specifically how to isolate tilt issues to camera or focuser which will help a lot.

[Ramius (Bill)]

Martin
I looked at the GSO Linear Bearing focuser when first considering a Newt. They do look good though no rotator or more importantly tilt adjuster. Still interesting though - the linear bearing version looks like it would take a standard EAF focuser without special brackets etc.


Do I understand that it is a straight bolt in replacement for the original skywatcher focuser or does this require drilling new mount holes or other mods?

[Startrek (Martin)]

Originally Posted by Ramius

Martin
I looked at the GSO Linear Bearing focuser when first considering a Newt. They do look good though no rotator or more importantly tilt adjuster. Still interesting though - the linear bearing version looks like it would take a standard EAF focuser without special brackets etc.


Do I understand that it is a straight bolt in replacement for the original skywatcher focuser or does this require drilling new mount holes or other mods?

Bill,
All GSO focusers for Newts require a makeshift custom bracket ( like mine ) or 3D printed bracket like TS to mount a ZWO EAF ( ZWO have a note about it on their website , maybe they have a product now but I doubt it ) Most folk like me have made their own , I think I did post my photo in their focuser section years ago.

As far as swapping a SW to GSO focuser , it could be direct swap but like everything in Astro there’s always subtle differences. You may have look online at any reference drawings to show a dimensioned drilling pattern and hole sizes.

Martin

[Ramius (Bill)]

Martin

Thanks again. The GSO is a good focuser but overall I have some doubts. At this stage I am not sure the existing focuser is the source of the problem and if it is, there is no guarantee the GSO is better than the CYCK noting that the GSO gets some mixed reviews online including a less than glowing dedicated tilt test by Narrowband Channel. On top of that it would need new focuser brackets and mods to the tube and I would be giving up a rotator and tilt adjustment.

I will need to give it more thought if I am unhappy with performance of the existing rig after a full test.

[Startrek (Martin)]

In simple terms with no cost restraints I personally recommend either intermediate f5 Carbon like I did or high end premium f4 Carbon as I mentioned previously.
I’ve seen so many folk on this forum using budget entry level f4 scopes and struggling for months and months to achieve a good Star field , some fix the issues , some just give up.
You have to throw money at f4 and faster as they require precision optics and precision mechanics.
I do hope you resolve things
Martin

[Ramius (Bill)]

Yes I agree that F5 would have been the better choice though i am still bemused that I seemed to have no significant problems with the first two targets. I will post a conclusion when i next get a good clear night.
Cheers

[rmuhlack (Richard)]

when collimating with the OCAL, is the scope on the mount? if so what direction is the scope pointing, and does the collimation (according to OCAL) change as the mount slews? that might help isolate where the problem lies. And given the trivial weight of the OCAL, if collimation remains solid according to OCAL no matter where the scope is pointing, that would suggest the issue is focuser related (maybe drawtube sag from the weight of your imaging camera gear)

[rmuhlack (Richard)]

and when you said there is no tilt, how did you confirm that? I use the NINA aberration inspector, which (together with a tilt adjuster) allowed me over successive runs of the tool and repeated tilt adjustment to remove residual tilt from my f2.8 hyperbolic newtonian.

[Ramius (Bill)]

Richard
Yes collimated on the mount and no noticable change when slewed to various locations - so yes I agree it is most likely sag somehere due to the weight of the (ASI2600) camera. That said i think i dialled out a lot of the sag when i went through and checked everything in the image train notably the focuser tension.
What I hope to do now is to the eliminate the tilt/sag readings with the focuser tilt adjuster (until now i have been faffing with the camera adjuster) then run a full nights imaging to see what variation i get at different locations. If the variation is acceptably small I will call it a day - if not... ?

[Ramius (Bill)]

Regarding tilt - I have been using the tilt tools in ASI Studio and ASTAP but for this next round I intend using Hocus Focus in Nina.