Rosette Nebula

[allan gould]

I had to clean my camera and filters as it looked as if my wife had used it to beat the carpets with - too many dust particles. So to test it I did a quick and dirty Rosette Nebula with 45 min Ha: RGB 15 min each using the 5" apo.
I cut this short as I wanted to get some images of the Sn in NGC1404 reported by the BOSS team.
Anyway I was surprised at the ability of my cleaning to remove all dust motes as well as the filters to be actually parfocal and the scope to hold focus well all night without the need to refocus. Happy to get some time in the dome at last.
Comments welcomed.

[ozstronomer (Geoff)]

Nicely done Allan, is there a bit of ringing around the larger stars?

[DavidTrap (David)]

Very nice Allan.

What filters are you using? FocusMax finds a difference between my parfocal astrodon filters. They're close, but still a few clicks between them. Mike told me his Astronomic filters have slight differences, even behind an AP scope which you'd hope would have the closest focusing point across the spectrum of any scope.

DT

[DavidU (Dave)]

Lovely Al, nice detail.

[strongmanmike (Michael)]

Originally Posted by DavidTrap

Very nice Allan.

Mike told me his Astronomic filters have slight differences, even behind an AP scope which you'd hope would have the closest focusing point across the spectrum of any scope.

DT

Yes but the focus difference was between colours, I found on occassions I felt needed to tweek the blue focus..? Not sure if this was the filter or the colour correction of the APO lens, I always suspected the later

Nice shot Alan, I would love some time back in my dome too

Mike

[DavidTrap (David)]

Originally Posted by strongmanmike

Yes but the focus difference was between colours, I found on occassions I felt needed to tweek the blue focus..? Not sure if this was the filter or the colour correction of the APO lens, I always suspected the later

Nice shot Alan, I would love some time back in my dome too

Mike

Thanks for clarifying that Mike.

Just to take this a bit further (sorry for the thread hijack Allan) - have you seen less focus difference with your new scope, or does the corrector cause similar issues? Am I safe to assume that if you can see focus differences for a high end refractor, you will need to refocus for each filter if your imaging train includes any lenses?

Ta
DT

[allan gould]

Originally Posted by ozstronomer

Nicely done Allan, is there a bit of ringing around the larger stars?

Geoff
Should have answered this earlier, but here goes. When I looked at the subs critically the blue set had more bloated stars. I cant say exactly whether this was due to the scope, the filters or a combination of both. But I do suspect that the focus needed a slight touch up for this colour. Since the series I was taking was a repeating Ha,R,G,B the filters just cycled through and the Ha, R and G were fine. I should also state that these young stars are blue (that look bloated) but I've desaturated them with crappy processing.
The filters were astronomiks, in the 5 position 1 1/4" size that they claim are par focal. But as I said in the original post I just wanted them clean and was testing them and also getting an idea of the field of view of the 5" scope.
Then as usually happens with me I got distracted by reading about the NGC1404 Sn and just had to get some data there. By the time I'd taken flats etc it was 3 in the morning and time to pack up after a great night.

[allan gould]

Thanks Mike and I agree with you re the refocusing etc.

Originally Posted by DavidTrap

Very nice Allan.

What filters are you using? FocusMax finds a difference between my parfocal astrodon filters. They're close, but still a few clicks between them. Mike told me his Astronomic filters have slight differences, even behind an AP scope which you'd hope would have the closest focusing point across the spectrum of any scope.

DT

David, don't have the luxury of computer controlled focus, just a Bahtinov mask and a touch of the lazies. You may be right about the blue.

Originally Posted by DavidU

Lovely Al, nice detail.

Thanks Dave

Originally Posted by strongmanmike

Yes but the focus difference was between colours, I found on occassions I felt needed to tweek the blue focus..? Not sure if this was the filter or the colour correction of the APO lens, I always suspected the later

Nice shot Alan, I would love some time back in my dome too

Mike

[Ross G]

A beautiful photo Allan.

Great detail and colours.

Ross.

[multiweb (Marc)]

Yeah, great details. Love the star colors and processing too. Top notch.