My first narrowband composite - IC410 in HST Palette

[vincentnm]

Hi All,

Been imaging in Ha with a DSLR for a while. But recently acquired OIII and SII filters from Nik Szymanek and a mono camera from Rob Hodgkinson. My first proper narrowband composite, not too bad I guess.

Thanks to the lousy weather in the south east, I had to spend 6 nights in Feb. Capturing just 4 to 5 subs

a night between the clouds.

Processing was a new challenge as opposed to OSC. Had problems with star bloat in SII and halos due to F/2 of the Hyperstar. New set of problems in aligning the Ha, OIII, SII. MaximDL would not do Auto Correlation or Auto Star matching. Did a manual 2-star align and then ran Auto Correlation and Auto Star matching in that order. That did improve alignment accuracy.

Used PixInsight DBE to get rid of gradients. Struggled to get the colours right with CS3. Even after endless tweaking, not sure if the colour balance is correct. Did some selective sharpening wherever the signal was strong.

Lots of advice welcome, especially with the processing.

If anyone's interested in processing, here's the stacked and calibrated frames, with no post processing - Download IC410.zip, upload your files and earn money.

Scope: C8 with Hyperstar

Camera: Starlight Xpress SXV-H16 mono

Filters: Astronomil 12nm Ha, OIII, SII

Guiding: Skywatcher ST80 with DFK

Mount: Skywatcher EQ6

Exposures: 2 hours Ha, 3 hours OIII, 2.5 hours SII.

Thanks

Vincent.

[RobH]

Nice work Vincent, and good to see the camera is producing decent results for you

You won't be getting the full benefit of the NB filters at F2, as they are designed to work properly at F4 and above...it's all to do with the angle of the light cone, so you've done a great job.

Interestingly enough, I have also been imaging IC410 in the Hubble pallette, and did a quick process today, but even with over 5 hours of SII, have very little signal to play with. I'm at F8 with a 6 inch scope though, so much slower than your F2.

Cheers

Rob

[narrowbandpaul]

very nice vincent!

maybe a touch more red to achieve the best colour balance?

welcome to the dark side of emission line imaging

nice!

paul

[Tim]

Nice one Vincent, as Rob says, everything shifts at F2 and you start to lose signal with the emission filters.

The colours are a devil to get "right", and that is partly because there is no "right", they are all false colours after all, but if a nice colour balance can be achieved that is easy on the eye, then that is half the battle.

This is my current project as it happens, currently have about 30 hours of data for it, im not sure how that many hours gathered at f5.3 balances against 7.5 hours at f2, but you seem to have a good amount of detail and reasonable stars too. Nice one

[Tim]

As for the combining of the channels Vincent, i find Registar to be incomparable. It will easily align them, you can choose which of your channels to calibrate the others to, and also asign them to their respective RGB channels as well, all with a couple of clicks.

[moocher]

Thats a nice first HST image Vincent!!! As its already been said you will struggle with NB filters at f2 but i`d be happy if it was my image!!!!

Alan

[vincentnm]

Thanks all for your comments.

Rob,

I had been warned about band shifting of narrowband filters at F2. I did some reading and there were suggestions that it does not matter for bandpass greater than 10nm. So I went ahead and bought 12mn filters. It may not be so bad, but the effect may still be there. Look forward to seeing your IC410.

Paul,

You're right. Its missing a bit of red. Thats the deficiancy of the SII signal. I tried to stretch the red channel, but I ended up with red halo'd stars. Only solution is to get more SII signal?

TJ,

Thanks for suggesting Registrar. Seems to be quite popular as many people have suggested the same.

Thanks,

Vincent.

[GordonH]

Hi Vincent

An excellent shot and as has been said, there are difficulties with narrow band imaging at faster than f4. Regarding the colours, you may find it worth while playing around with selective colour in photo shop if you use it. There is a very good section on Focal Pointe Observatory that explains how to do this and it can help bring out the colours better when using narrow band imaging. If you go to the link and then click on image processing and then where it says Hubble palette processing

Best wishes

Gordon