Weird stars again.

[emyliano2000]

4 minutes ago, Sland said:

but did you test you spirit level for accuracy before doing this?

How? Turn it the other way around? If yes, I did do that. ?

[alacant]

On 31/08/2018 at 21:16, emyliano2000 said:

That's what I always use for collimation.

Hi. So the problem occurs after attaching the camera.

 

On 22/08/2018 at 14:35, emyliano2000 said:

Before I fitted the new focuser

Not sure what the new and old focusers are. FWIW, I gave up on the dual speed sw crayford due to problems like the ones you mention. This one works well as do the big old fat tube models. HTH.

[emyliano2000]

13 minutes ago, alacant said:

. So the problem occurs after attaching the camera.

 

If you're thinking of sensor tilt, I ruled it out because it's the same on both my cameras.

 

44 minutes ago, alacant said:

Not sure what the new and old focusers are

The old one is the stock skywatcher and the new one is a baader steeltrack

[alacant]

5 hours ago, emyliano2000 said:

you're thinking of sensor tilt,

Hi. No. Attaching the camera changes something. Your collimation must b good using a sight tube so it must be something happening after you attach the camera. Is the star field always affected in the same corner e.g. is the distortion always bottom right after crossing the meridian with the camera now at 180º?

Can't be far off now...!

[emyliano2000]

A friend of mine suggested that the OTA might sufer some kind of distortion when I fix the focuser to it and that some kind of support plate might reduce that. The baader focuser comes with 4 little metal plates used to fit the focuser on smaller OTAs and I thought of using them when I fit the focuser to see if there's any difference. 

There is a difference, the stars in the photos are looking better, the tilt is considerable reduced but on the bottom right the stars look like they've been knocked.

[emyliano2000]

The problem might also come from how the camera is fixed to the focuser. The baader focuser is using a commpression ring which can possibly have a bad effect on getting everything lined up correctly. I thought of an all screw connection but if I remove compression ring adapter, there is no thread. The compression ring adapter has a S68 dovetail and it's fixed to the focuser tube by 6 hex screws. I would probably need a dovetail S68 to female M48 custom made adapter so I can permanently fit the baader mpcc inside the focuser tube and use its M42 adapter to connect my camera.

[emyliano2000]

I just found this. It might be useful.

COLINST3.pdf

[david_taurus83]

I too have thought about the flat base of the focuser causing some sort of flexure in the tube when fitted. I have a Skywatcher low profile one (below) with a similar flat base to the Baader. I've often wondered because the base doesn't conform to the curve of the OTA if by tightening the screws is causing the OTA to warp slightly. Mines a steel tube version though. Is yours carbon?

[emyliano2000]

1 hour ago, david_taurus83 said:

Is yours carbon?

It is a 10" carbon fibre quattro. It came cheap, £250 and I couldn't resist but omg so many problems.

[david_taurus83]

28 minutes ago, emyliano2000 said:

It is a 10" carbon fibre quattro. It came cheap, £250 and I couldn't resist but omg so many problems.

"Problems". I've turned to a refractor for imaging now ?

[emyliano2000]

3 minutes ago, david_taurus83 said:

refractor

I am using one for widefield but for small targets I can't afford to pay big bucks and get a refractor.

[emyliano2000]

This was taken with the 10" quattro when I was testing it. Blue snowball nebula. Stars look bad but I like to capture small targets too.

 

[emyliano2000]

I think I found a way to make an all screw connection. I would have to spend another £100 ? though.

The baader mpcc will stay permanently inside the focuser.

M68 adapter for diamond steeltrack which would be fixed on the focuser draw tube instead of the compression ring adapter, then a 12mm M68 continuous female thread ring to convert the M68 male into M68 female and a M68 male to M48 female adapter.

The baader mpcc will be housed permanently inside the focuser draw tube connected in M48 mode to the last adapter. The camera or other accessories will be connected to the baader mpcc via the M42 adapter that came with it.

What do you think, would this work?

 

[david_taurus83]

Not saying my method mentioned earlier is the answer, but I would at least try and align the Baader drawtube the same as the stock one, or at least check if they are the same, before spending more.

[emyliano2000]

55 minutes ago, david_taurus83 said:

Not saying my method mentioned earlier is the answer, but I would at least try and align the Baader drawtube the same as the stock one, or at least check if they are the same, before spending more.

I can't really trust the stock focuser because it also has its own problems.

If you look at the stock focuser, it has the compression ring adapter screwed to the draw tube then a little deeper inside the tube there's a narrower side. The coma corrector doesn't fit in that narrower side and because of that, it doesn't go all the way in the tube. To be able to fully insert the coma corrector inside the tube, I need to add a M54 extension to the focuser draw tube.

 

[Guest]

On 04/09/2018 at 23:45, emyliano2000 said:

How? Turn it the other way around? If yes, I did do that. ?

Good man!

[emyliano2000]

I've done, it, I fixed he tilt on the Baader focuser and got the spacing right too.  Going to shoot at f3.6 with the 0.9x coma corrector

Happy days! ??

[Thalestris24]

Hi

What did you do to fix it in the end?

Louise

[emyliano2000]

5 hours ago, Thalestris24 said:

Hi

What did you do to fix it in the end?

Louise

After fitting those small metal plates on the inside and outside of the tube I decided to put a very thin shim in the corner of the focuser where the stars didn't look right. That fixed some of the tilt. The compression ring adapter on the focuser tube and the design of the coma corrector have their part of the blame too. The coma corrector has like a groove on it where the compression ring should sit but unfortunately it doesn't so I have to be careful how I tighten it. An all screw connection will fix that problem.