Centaurus A

[Itchy]

Hi Everyone,

I'm still bored, so I took a look at another image I took back in February of Centaurus A. I decide to reprocess these from scratch. Now I think I've learned a trick or two about processing in that time. I think this also demonstrates that processing is more than half the battle. I thought I did a pretty good job back then, but I now use quite different techniques.

(don't look too closely at the stars, I didn't have my Coma corrector back then) :whistle:

26x60sec and 8x120sec, LXD55 SN10, Canon 300D, ISO1600

Anyhow here is the comparison.

[Exfso]

Does the coma corrector actually work on the SN10. I thought it may interfere with the corrector plate. What did it cost and did you get it locally if you dont mind me asking.

[cventer]

Nice work. Much better job indeed.

You should try describe the differences in processing so beginners know how to remove those noise gradients (lines running at 45 degrees) in your original.

Best Regards
Chris

[Itchy]

Hi Exfso

Yes, it actually does work. I have the Multi Purpose Coma Corrector by Baader. I was not able to source it here in Australia. I eventually got it from Alpine Astronomical. Pricing is on the site ($US).

http://www.alpineastro.com/optical_accessories/optical_accessories.htm

There was some speculation that the MPCC would overcorrect on the SN scopes. One guy from the States has done some ray tracing on the combo. He says that there is very slight over correction in the centre of the image and there are also slight problem with chromatic aberation. Also, if I can trim my T-mount adapter by 4 mm, I am told that it will perform even better (I'm not about to do that btw). All I can say is that my images are much better with the MPCC than without it. Check out my other thread on the tarantula (Gee I'm Bored). They were taken with the MPCC.

Cheers

[Itchy]

Thanks Chris. Much appreciated.

I will post something in that regard, but not tonight. I'm off to get my beauty sleep:rofl: (you will know how funny that is if you have seen my mug shot in general chat).

[xelasnave]

Funny I just came from astronomydaily.com wherein I said that I heard someplace processing was half the battle so it was amusing to read your post here .. making my recollection a fact in retrospect.. anyways that sums up my boredum I guess.
I certainly for one would like to know how you got rid of the 45 degree lines.
AND last of all great work it is worth doing these projects even if not bored.
alex

[Exfso]

Thanks Tony very much appreciated. I was wondering what else I could add to my SN10 to give it a bit more grunt. Now I have my pier and the losmandy it should fit nicely. All I need to do is to fill my pier tube with sand to dampen vibrations. It will definitely need something with the SN10 mounted up.

[RB]

Great improvment there Itchy,

Your boredom is very educational to me.
:face:

[iceman]

Very nice Itchy! A much more pleasing result.

[FOOTPRINT]

Hi Itchy,
Very nice picture of Cent.-A, I note you combine images, can you let me know what software you use to do so, ive never done any good with DSLR image combining, so go to the sky fog limit 10 Min. or so at ISO800, good results but sometimes seeing will not allow long exposures, so im very interested getting combining to work.

regards..Jim

[ving]

i cant see any difference... just kidding :P
great stuff!

[atalas]

Hi Tony, yes I see a huge difference there very nice.

[Striker]

Gorgeous.....

I like to keep it short.

[davidpretorius]

well done itchy!!!

[Itchy]

Hi Footprint



Thanks for the positive feedback.

I use ImagesPlus to convert, calibrate, align, combine and intitially stretch my images. It is fantastic. As soon as I got it my images started to improve. It is a bit pricy but the support and constant upgrades (via a beta program) make it well worth the money. I think it is on special up to Christmas.
:xmas:

Cheers

[asimov]

Nice mate!

[Itchy]

Thanks to everyone for the feedback.

As I have said, I've learned a lot about processing over the last 12 months. Having said that, I recently found out how much I don't know! I met a guy from ASNSW at our last imaging meeting who blew me away with what he knew about photoshop and the processing of asto images. I think his name is Mick McCollough. I picked a few bits but just scratched the surface.

Anyhow, a couple of people requested an explaination of the differences in Processing these images. It was back in February that I did the first one, so I'll do my best:

The February image was converted from RAW to linear 16 bit Tiff using ImagesPlus. The subexposures were calibrated using a masterdark made of about 5 dark frames and a master flat made with about 8 or 9 flats. The calibration worked reasonably well, but left a gradient that I had no way of dealing with. I combined the images using average combine and then used IP's Digital Development to stretch them. All I did was to use the Auto settings and it produced a pleasing looking image. It was some time later that I learned that using the auto setting actually resulted in severe clipping of the faint data. I then finished off the image in Photoshop, doing my best to bringout what I could using levels and curves.

The main difference in basic processing this time around was that I used No White Balance CFA (Colour Filter Array) conversion on the lights and the calibration frames. This Pre-Bayer processing allows for much more accurate calibration. Also I have constructed a new set of Flats using 22 subframes and I used a masterdark made from 20 dark frames. These calibration frames were applied using ImagesPlus 2.75 bets 4, which has a really neat Auto dark frame matching routine. This allows for much more flexibility in the temperature variation of the darks. Also my techinque of using Digital Development has improved as well. I now only use Auto as a starting point, and keep a close eye on the histogram while performing the stretch. This way, I concentrate on the histogram shape rather than what the image looks like, thereby avoiding the clipping. Once I took the Image into Photoshop, I discovered that the image was much easier to adjust, and interestingly the gradient was gone. I can only put that down to a better flat frame. The lower background noise is probably due to the more accurate calibration and the use of auto darkframe matching. The master dark was much smoother too.

Another difference was the application of ImagesPlus Star Size and Halo reduction tool (also in beta). About the only other thing that was different was the Highpass filter mask that I used in Photoshop to enhance the detail in the dustlanes. I have briefly describe that in another recent thread, so I won't bore you with that again.

If you have any questions, ask away.

Cheers

[FOOTPRINT]

Hi Itchy,
O.K. thanks for the info. on Images Plus, ive had a go with it but the Videos are a bit much to follow, I see Staraziona will be putting out an text version of instructions soon, ill have another go then.

cheers....Jim