The Pelican - B/W

[PhotoGav]

I almost daren't put this up given Sara's fantastic image of this area, but, what the heck... Forget fancy Taks, here's my SWatch version of The Pelican!

Skywatcher ED80 with reducer, QSI 683 with baader Ha filter. 12 x 1200s. Calibrated with darks, flats & bias. Processed with Nebulosity 3 & PS CS5.

I can't help but notice, in my strive for perfection, that the corners have slightly elongated coma-esque stars. What would cause this? The optical train is: 2" adapter, focal reducer, 5mm spacer, camera. Is it to do with the spacing not being quite right I wonder?

As ever, all comments greatly received, especially thoughts on how to improve.

Thanks.

[red dwalf]

very nice image,

spacing can be a big problem especially with my William Optics GT, given me a few headaches. Not too sure about other scopes but didn`t seem to be as big a problem with my Starwave 80 ed 

[RCG]

I am old enough to remember when only professional astronomers, with big telescopes, could hope to make images like that.

[Epicycle]

That's a very nice Pelican, showing very good detail at the core and filaments.

The 683 has a large chip, so spacing is more critical and since you seem to have elongation on all corners most likely is not tilt...

[swag72]

There's nowt wrong with that Gove - Mighty nice indeed. Perhaps just have a play with your spacing to see if it makes any difference?

[Ace_Dante_Sparda]

Woah! EPIC IMAGE!

[gingergeek]

Yep, a cracking image from the fantastic ED80

[PhotoGav]

Thank you for your comments all.

On the star elongation... I checked the individual subs and I think that it is tilt, not coma. The subs were from both sides of the meridian and they all have elongation at the same end. It is the combination of all the subs, with half flipped, that creates the elongation in all four corners, making it look like coma rather than tilt! I think that I will ditch the push fit adapter and try screwing the flattener directly onto the focuser and see if that eliminates it. I only used the adapter so that I could use a 2" LP filter, but I'm not having to use that any more. Hopefully the next target will be properly flat!

[Epicycle]

Thank you for your comments all.

On the star elongation... I checked the individual subs and I think that it is tilt, not coma. The subs were from both sides of the meridian and they all have elongation at the same end. It is the combination of all the subs, with half flipped, that creates the elongation in all four corners, making it look like coma rather than tilt! I think that I will ditch the push fit adapter and try screwing the flattener directly onto the focuser and see if that eliminates it. I only used the adapter so that I could use a 2" LP filter, but I'm not having to use that any more. Hopefully the next target will be properly flat!

Oh, I see, that sounds very plausible, hopefully you'll be able to sort it out one way or another

E.

[PhotoGav]

Oh, I see, that sounds very plausible, hopefully you'll be able to sort it out one way or another

E.

I hope to give it a try tomorrow night - the forecast is good and hopefully it will be that simple! Oh well......!

[sharkmelley]

Beautiful image and very well processed.

Mark

[Martin-Devon]

Really nice image Gav.

[PhotoGav]

Thank you Mark & Martin. This was the first time using CS5 and it is a definite improvement over CS3. Unfortunately my ageing MacBook is too feeble to run CC! Shame they no longer make a 17" MacBook, though the finance director is quite relieved...

[PhotoGav]

Little update on the tilt / coma issue... I screwed the FF/FR directly on to the focus tube and the stars are now perfect all the way to each corner. So it was tilt caused by the push fit adapter not sitting orthagonally (if that's the right word) in the focus tube adapter. That adapter only has two screws to hold things in place and not a lovely compression ring, hence the bad fit. So, be careful any fellow SW 80ED users out there! I wonder if there is an upgrade part to replace it that does have a compression ring?

[kingboya]

Little update on the tilt / coma issue... I screwed the FF/FR directly on to the focus tube and the stars are now perfect all the way to each corner. So it was tilt caused by the push fit adapter not sitting orthagonally (if that's the right word) in the focus tube adapter. That adapter only has two screws to hold things in place and not a lovely compression ring, hence the bad fit. So, be careful any fellow SW 80ED users out there! I wonder if there is an upgrade part to replace it that does have a compression ring?

Glad you sorted the problem. Regarding the focuser, an upgrade is probably the best and easiest option?

Lovely image. I am seriously considering this camera sometime. Big step up from the 314L, not only in cost, but also quality.

Images like this make holding back HARD!

[PhotoGav]

Glad you sorted the problem. Regarding the focuser, an upgrade is probably the best and easiest option?

Lovely image. I am seriously considering this camera sometime. Big step up from the 314L, not only in cost, but also quality.

Images like this make holding back HARD!

Cheers. Needless to say, I highly recommend the QSI! It was another SGL assisted purchase and I don't regret a single penny of it. I upgraded the guide cam at the same time and that seems to work perfectly, though all my targets so far have been in very star-rich areas.

Yes, I have looked at a focuser upgrade for the 80ED and always get sidetracked by the Williams Optics section and the 71 or 81. It's only a 'little bit more' than an SI Feather Touch upgrade!