My last Carina for the season

[RyanJones]

Hi all,

Since changing my setup significantly over the last few months, I’ve started to get a handle on it again. I’ve been working on other targets from my dark site and getting some good data. I thought it would be good to try the same setup at home ( Bortle 8 ) and see what I could do. I thought I’d start with a bright target so Carina became my victim.

I’m reasonably happy with what I achieved. Some double diffraction lines on the lower right so I don’t think my mirror alignment is right ( primary to secondary ). I’m happy to be corrected if that is caused by something else. Collimation was good through the Cheshire. Generally speaking though, I’m pretty happy.

Vixen f/5 Newtonian guided
Canon 350d modded
40 x 180 sec ISO 400
CLS CCD Filter
Baader MPCC

Cheers

[Outcast (Carlton)]

Nice one Ryan...

[gb44 (Glenn)]

Thoroughly excellent job. I'm looking forward to M8 and M16.

How did the collimation appear visually with a high power eyepiece - the final step in newt collimation?

GlennB

[RyanJones]

Thank you Carlton and Glenn.

I’m looking forward to M8 and M16 too. I’m planning on trying my 9.25 at prime on the Pillars in M16 but we’ll see how that goes.

As far as using a high powered eyepiece goes, I wasn’t aware of doing that after collimation. Is that the same as the concentric doughnuts you do with an SCT ? When I was focusing the doughnuts did look good out of focus but that was with a 21mm EP. As I said though, I didn’t concentrate on it or attempt to make any final adjustments.

[gb44 (Glenn)]

Also M17 and M20, the list is infinite.

Have you seen this on collimation?

http://www.astrophoto.fr/collim.html

Take the time to do it as it pays off. I was always frustrated by the newt mirror slop and the loss of collimation between targets at differing altitudes. I had bearings to keep the mirrors centred. I had tried silicone - ing the mirror to the whiffletree but it caused difficulties. Maybe best combo is a short tube astrograph and a big apo.

Good luck
GlennB

[RyanJones]

I hadn't seen that article Glenn but it's an interesting read so thanks for that.

I'm going to try something different tonight to see if I can extract more colours If the cloud clears

I'm really looking forward to this winter as all of the targets I stated on a year ago when I started imaging are coming back. It quite amusing now to look back at what I was happy with this time last year.

[Karlzburg (Karl)]

That newt was easy to collimate, I would always do a quick star test as a check before imaging and never had issues.

[RyanJones]

Hey Karl,

I had to pull it down a while ago to clean it and found one of the collimating screws for the primary was hard up against the back of the mirror. Also the secondary screws had burred the back of the secondary holder so I couldn't rotate it to centralise it. Since I sorted it and collumated it it has been really good. This is the first image I've noticed the double lines on. Looking futher into the image though I'm thinking it might have been tilt rather than collimation because the other stars' defraction lines seem fine.

[Startrek (Martin)]

Beautiful image Ryan
Well done !
Just a quick one , do you find using the Baader coma corrector “softens” the stars a bit ?
I do, I’ve done a test with and without and although without using it I get coma in the off axis areas, the stars and their diffraction spikes seem longer and sharper , sort of “spikier”. Maybe there’s a penalty or sacrifice to pay in correcting your coma ? You are introducing another set of optics into the system.
Just an observation
Cheers
Martin

[RyanJones]

Thank you Martin,

To be honest I hadn’t noticed the difference in the defraction lines. I might have a look back over some of my pre-cc images to see. My coma pre correction was so bad that I concentrated more on the fact I could get round stars off axis. Interesting observation though.