IC 4628 in H-alpha

Peter Ward · #1 09-05-2009, 09:09 PM

A work in progres...

http://www.atscope.com.au/BRO/gallery40.html

AlexN · #2 09-05-2009, 09:38 PM

have to be happy with that so far!

Nice image, and interesting target.

Alex.

Alchemy (Clive) · #3 09-05-2009, 10:21 PM

ah the prawn,

be nice to see it colored up, HaRGB ,Narrowband, or some other blend perhaps?

Peter Ward · #4 09-05-2009, 11:56 PM

Quote:

Originally Posted by Alchemy

ah the prawn,

be nice to see it colored up, HaRGB ,Narrowband, or some other blend perhaps?

A raw prawn at present.....

strongmanmike (Michael) · #5 10-05-2009, 06:58 AM

Nice job so far Peter but the stars are so pin point (obviously not the RC) that those (like me) with a bit of astigmatism will probably say they are little eggs

I never realised just how much my slight astigmatism affected tiny dots on the screen, lots of sharp images looked like they had guiding error, I now put my nose to the screen or enlarge the image just to make sure before coming to such a conclusion

Mike

spearo (Frank) · #6 10-05-2009, 07:00 AM

nice detail in there
it'll change color as it cooks a bit!
:]
frank

Ric · #7 10-05-2009, 10:27 AM

Lovely work Peter, the wisps and folds of the nebulosity look fantastic.

Cheers

Peter Ward · #8 10-05-2009, 12:03 PM

Thanks one and all for your feedback....

On the subject of elongated stars

.... I have been doing some fine tuning of my RC system recently using CCDinspector software.

Some results can be seen here
http://www.atscope.com.au/BRO/tutori...inspector.html

It's certainly a useful tool, but does give different colimation resuts by simply imaging a different star field, or with the same field but with different seeing or with a slight focus tweak

That said, subtle tweaking of a system can make significant differences the overall performance....just need some clear weather to see the
results!

Jen · #9 10-05-2009, 01:47 PM

very nice Peter

multiweb (Marc) · #10 10-05-2009, 06:34 PM

Wow!

Some real nice details in that picture and great dynamic range and contrast. Not an easy one to process. Can't wait to see the final with the color.

Hagar (Doug) · #11 10-05-2009, 08:00 PM

Very nice result so far Peter. Look forward to seeing the end result.
CCD inspector seems to be a quite usefull addition to the collimation process. I have recently been investigating it's use but need some clear sky and time to make it all happen. Do you know of any tutorials for it?
One more question, What length subs do you use for your Ha imaging?

Craig_L · #12 10-05-2009, 08:07 PM

Great shot Peter. So much detail yet so little noise for the relatively short exposure. What software do you use for noise reduction?

Peter Ward · #13 10-05-2009, 08:41 PM

Quote:

Originally Posted by Craig_L

Great shot Peter. So much detail yet so little noise for the relatively short exposure. What software do you use for noise reduction?

I generally never use noise reduction software... certainly none was used here.

An 'oft mis understood feature of the camera I use (no prizes for guessing the manufacturer

) is their dead-nuts-accurate chamber temp (patented) so provided you take accurate darks and flats, the calibrated image noise is extremely low....provided you keep the shot noise down by using long enough sub exposures. With H-Alpha I typically use 15 minute subs.

20 minutes would be better, but they greatly increase the probability of my also capturing an aircraft ( living under an instrument arrival waypoint into Sydney)

My advice would also be...if the data is noisy, simply expose longer to get more signal.

Craig_L · #14 11-05-2009, 05:14 AM

Thanks Peter for the info. Looking forward to the completed 'work'.

Craig

rat156 · #15 11-05-2009, 08:09 AM

Hi Peter,

There's something wrong with your AP155, it's producing diffraction spikes. Have you been cleaning the objective with steelo again? Other than that I really like the framing of this one.

Cheers
Stuart

Peter Ward · #16 11-05-2009, 09:33 AM

Quote:

Originally Posted by rat156

Hi Peter,

.....Have you been cleaning the objective with steelo again? .......

Cheers
Stuart

Nah....just Ajax powder cleanser

Paul Haese · #17 11-05-2009, 06:59 PM

Great data Peter. Looking forward to the end product.

Martin Pugh · #18 15-05-2009, 11:08 AM

Nice work thus far Peter.

but I cannot fathom how you are getting diffraction spikes on the brighter stars using a refractor. Never seen that before.

cheers
Martin

AlexN · #19 19-05-2009, 09:00 PM

my two guesses..
1. Software added diffraction spikes, added either to give the image a bit of flare until it gets some RGB data, or to keep us on our toes!

2. Diffraction mask on the scope.. Personally I dont see someone adding a diffraction mask in front of such an impressive objective lens, however I suppose, why not on the odd occasion?

Peter Ward · #20 19-05-2009, 09:27 PM

Quote:

Originally Posted by Martin Pugh

Nice work thus far Peter.

but I cannot fathom how you are getting diffraction spikes on the brighter stars using a refractor. Never seen that before.

cheers
Martin

I suspect this data set has taken me into dead end street.

The diffraction spikes are real, (fishing line over the AP dew shield...) but are in retrospect not necessary.

My framing was intended to capture both the open cluster and nebula, yet it just doesn't have the right "eye pleasing" balance.....

I'm thinking a re-shoot at a shorter FL is the next step....of course only to be hampered on my days off by the usual waning moon rain!