How's my collimation? - advice please.

[Adreneline]

Last night I managed to use my new GSO 6" RC for the first time.

When I started out on the AP path 4 years ago my first image was M31 so I thought it only right that I image M31 with the new OTA using the Canon 70D unguided but on my CEM25-EC (not the NEQ6 which I sold).

This is manually focussed and manually dithered (!) and captured using BYEoS which reported an FWHM of 4.2 on my target star. The image comprises 20 x 120s lights stacked in DSS and post-processed in PI and PS. There are no flats ( I took them but they are all mis-orientated as I forgot to turn off the auto-rotate feature on the camera!) but I did take darks and bias. 

As I am completely new to reflector type scopes I would really like some advice on the state of collimation as the scope came "straight out of the box".

The lack of guiding is evident although I feel the CEM25 coped really well with the payload; I did spend an age carefully balancing the OTA+camera.

The intention next is to use the ASI1600 with ASIair but it was easier in the first instance to take advantage of the LiveView on the Canon.

Thanks for looking and any advice would be much appreciated.

Adrian

 

[vlaiv]

Not quite good - you should collimate your scope for sure.

I think that even your secondary is not properly aligned - and that is rather easy to do.

[AweSIM]

4 hours ago, vlaiv said:

Not quite good - you should collimate your scope for sure.

I think that even your secondary is not properly aligned - and that is rather easy to do.

How were you able to tell? 😮 And how is the secondary easier to adjust than the primary? I thought it was the other way around.

Edited August 7, 2020 by AweSIM

[vlaiv]

1 minute ago, AweSIM said:

How were you able to tell? 😮

Which part? That it needs collimation? That is kind of obvious - look at the star shapes:

Here is collimated RC scope (RC8):

Stars are tight and round.

Another telltale is that stars look different in different corners and they are not round even in center. If primary is not aligned properly but secondary is - then stars will be distorted in corners but not in center, a bit like this:

Close to center:

Corner

:

[AweSIM]

1 minute ago, vlaiv said:

Which part? That it needs collimation? That is kind of obvious - look at the star shapes:

Here is collimated RC scope (RC8):

Stars are tight and round.

Another telltale is that stars look different in different corners and they are not round even in center. If primary is not aligned properly but secondary is - then stars will be distorted in corners but not in center, a bit like this:

Close to center:

Corner

:

Thank you so much for the insight!