coma corrector fitted, happy in general but..

[Dan13]

Hi everyone, attached my newly bought CC yesterday which on the whole is great, however ive found in post processing my stars seem to have a little tip to them now. is there anything i should be doing to resolve this by having a CC contected? they werent like this before hand. many thanks

Dan

[geordie85]

Where abouts are those stars in the image? It looks like a spacing issue or maybe tilt. 

Edited May 21, 2020 by geordie85

[Dan13]

1 hour ago, geordie85 said:

Where abouts are those stars in the image? It looks like a spacing issue or maybe tilt. 

Hi geordie, there to the left of M63 there like that all over the image.

 

I think you have just answered my question! I've checked and the t ring I'm using is m42 with the bracket taken out and I've used to grub screws to hold the cc in! I'm an idiot..... I've ordered an M48 adaptor, my guess is same as you know and probably tilt...

 

Thank you 

[Dan13]

On 21/05/2020 at 15:44, geordie85 said:

Where abouts are those stars in the image? It looks like a spacing issue or maybe tilt. 

Hi, ive now received the correct fitment (M48) for the SW CC and noticed my stars are still the same as above! i dint think a spacer was needed for the SW CC, do you know of any that i may need at all? @geordie85

Edited May 26, 2020 by Dan13

[Adam J]

looks like sensor tilt or maybe colimation.

[Dan13]

12 minutes ago, Adam J said:

looks like sensor tilt or maybe colimation.

Thank Adam, Coilmation i know was spot on last night so sensor tilt is a good shout, sorry to ask perhaps a stupid question but how would i rectify that if it was?

[Adam J]

Just now, Dan13 said:

Thank Adam, Coilmation i know was spot on last night so sensor tilt is a good shout, sorry to ask perhaps a stupid question but how would i rectify that if it was?

Depends on what camera your using?

[Dan13]

Just now, Adam J said:

Depends on what camera your using?

600d mate (mod)

[Adam J]

1 minute ago, Dan13 said:

600d mate (mod)

Well those have spring mounted sensors, they can be adjusted and if you are not careful when you remove the sensor for modification you can end up with tilt. The other big possibility on a DSLR is a poor quality T-ring allowing movement between it and the camera. The last possibility is your scope focuser is not colimated or is experiancing droop.

What scope is it?

Adam

[Dan13]

1 minute ago, Adam J said:

Well those have spring mounted sensors, they can be adjusted and if you are not careful when you remove the sensor for modification you can end up with tilt. The other big possibility on a DSLR is a poor quality T-ring allowing movement between it and the camera. The last possibility is your scope focuser is not colimated or is experiancing droop.

What scope is it?

Adam

Oh dear! 

Scope is 130pds, focuser hasnt been touched since i bought it. never had an issue until i used the CC

T-ring M48 is brand new and fitment is snug.

 

Maybe i need a spacer due to the senor being removed? i think id rather have coma then the stars im getting now haha

[Adam J]

19 minutes ago, Dan13 said:

Oh dear! 

Scope is 130pds, focuser hasnt been touched since i bought it. never had an issue until i used the CC

T-ring M48 is brand new and fitment is snug.

 

Maybe i need a spacer due to the senor being removed? i think id rather have coma then the stars im getting now haha

I used a 130PDS for imaging for years, try to adjust the tension on the focuser first of all on the bottom there are two grub screws that will adjust it.

The other issues with it is that if you are using just the two original thumb screws to attach the camera, those are insufficient and most people will drill and tap a third to stop droop.

You cant expect too much out the box from a £180 scope, when you see people taking fantastic images with them with perfect stars 9 times out of 10 its been modified in some way.

Adam

Edited May 26, 2020 by Adam J

[Dan13]

1 minute ago, Adam J said:

I used a 130PDS for imaging for years, try to adjust the tension on the focuser first of all on the bottom there are two grub screws that will adjust it.

The other issues with it is that if you are using just the two original thumb screws to attach the camera, those are insufficient and most people will drill and tap a third to stop droop.

Adam

Thanks Adam ill try the tightening it up, thats something i havent done, i will also look to drill and tap another hole and see if that helps at all. both can then be eliminated. thanks for your help with this.

[Adam J]

1 minute ago, Dan13 said:

Thanks Adam ill try the tightening it up, thats something i havent done, i will also look to drill and tap another hole and see if that helps at all. both can then be eliminated. thanks for your help with this.

No problems.

[Dan13]

5 hours ago, Adam J said:

No problems.

this is the final image Adam, bloody hard galaxy M63, tbf i only ended up with 4 hours data with all these complications, can you see the main big stars and the spikes? not sure why theres two of them now lol

[Adam J]

45 minutes ago, Dan13 said:

this is the final image Adam, bloody hard galaxy M63, tbf i only ended up with 4 hours data with all these complications, can you see the main big stars and the spikes? not sure why theres two of them now lol

That has two possible causes on a 130PDS,

1) Your spider vains are twisted and need a tweek

2) The coma corrector has pushed the focus position closer to the scope and as such the tube is now in the light path within the body of the scope, so it creates additional spikes just like the spiders and takes a chunk out of the left side of all your stars.

I think that you have a bit of both here. One is easy to fix two is not so easy and requires that you cut about 1cm or so off the focus tube to stop it happening. I did it on my scope. You then need to glue something onto the bottom runner to stop it from popping out when fully extended. Focus the scope then make a mark on the inside of the draw tube within the main body of the scope. Leave some tollerance 7mm or so when you cut.

measure twice cut once....

All you need is a hack saw and some patience. Looking at the star shap i would say this is a big part of your other issues.

Appart from that its a nice image.

Only other thing that would cause it is rotating the scope in its rings over two sessions.

Adam

Edited May 26, 2020 by Adam J

[Dan13]

24 minutes ago, Adam J said:

That has two possible causes on a 130PDS,

1) Your spider vains are twisted and need a tweek

2) The coma corrector has pushed the focus position closer to the scope and as such the tube is now in the light path within the body of the scope, so it creates additional spikes just like the spiders and takes a chunk out of the left side of all your stars.

I think that you have a bit of both here. One is easy to fix two is not so easy and requires that you cut about 1cm or so off the focus tube to stop it happening. I did it on my scope. You then need to glue something onto the bottom runner to stop it from popping out when fully extended. Focus the scope then make a mark on the inside of the draw tube within the main body of the scope. Leave some tollerance 7mm or so when you cut.

measure twice cut once....

All you need is a hack saw and some patience. Looking at the star shap i would say this is a big part of your other issues.

Appart from that its a nice image.

Only other thing that would cause it is rotating the scope in its rings over two sessions.

Adam

Excellent Adam thank you!

 

Were getting closer to the issue now then, I bought a new dovetail (bigger one) so had to adjust the scope rings! that must be the cause of the spikes!!  

Im guessing its no.1 because i didn't get the x.09 reducer version of the CC i got the standard one which actually made me focus out more then i currently was so def no protruding into the mirror path.

With regards to 1. im guessing you mean the arms that hold the mirror? the ones with the grub screws for coilmation?

 

thanks again this is great info