M83

[Shiraz]

Hi

Two LRGB versions - the first one is native scale and with muted colour - tried to match "science" images on the web. The other is higher contrast and with more saturation, but it had to be reduced to 80% scale to keep chroma noise and artefacts from being too annoying. The hotter version shows the star formation regions quite well - maybe will try to add some Ha to the full scale version in future to enhance the new star regions.

Mount tracking noise messed up the brightest stars and I did not take any care over them - concentrated only on the galaxy. None of the available software could handle the heavily polluted colour data (particularly the red), so needed to manually set gain and offset in each channel after stacking to get any sensible results. Roll on clearer skies :).

thanks for looking. Appreciate any feedback - been messing around with this data so much I can't see the woods for the trees anymore. Regards Ray

200f4 Newtonian with RCC1
SX H694
EQ6 with 50mm guidescope
LRGB 47:60:42:52

[marco]

Beautiful Ray! I like them both, honestly the first version less saturated is as good as it can be on this target, so I would keep that one :thumbsup:
Clear skies
Marco

[Larryp]

Lovely image, Ray. The first one appeals to me more. Great work!

[allan gould]

Most excellent images and processing. I can see advantages in both types of processing.
Allan

[RickS]

Both great but my preference is #1 too, Ray!

[gregbradley]

I like the 2nd one. Its sensational.

Greg.

[strongmanmike]

Excellent Ray! For me the second one has more grab, looks great mate!

Hmmm? I will be putting the H694 on the AG12 soon ;)

Mike

[tilbrook@rbe.ne]

Like the detail and colour saturation in your first image Ray.

Your stars look like mine, I use a bintel 200mm f/4 reflector. I have tried various fixes, new coma corrector, fixing flexure and always check collimation.
But the always come out the same.
You mention mount tracking noise, what is this?
Would appreciate if you could fill me in on this.

Cheers,

Justin.

[asimov]

Great work Ray. I love the second one best :)

[alpal]

Great work Ray,
That is very sharp & clear.

[Shiraz]

thanks very much for the helpful feedback Marco.



Hi Laurie - thanks



Thanks Allan. I also am a bit unsure which approach is best - thanks for your comments



thanks for the feedback Rick



hi Greg. very kind comment.



Hi Mike. thanks for the comments. Looking forward to you getting the 694 going in your new wind free environment - spare a thought for us plebs with an EQ6 swaying in the breeze :).



Hi Justin. I am not sure I am an expert on this, since I have been battling with this scope for years. However, I think that the current distortion is due to the mount producing very rapid tracking excursions that produce fleeting illumination outside of the main stellar spots. For dim stars, the excursions are too dim to see. For very bright stars, the excursions are smaller than the blobby stars so they do not cause distortion. for Intermediate brightness, the excursions are just bright enough to be visible, which leads to stars that vary in appearance with brightness. That's the theory anyway and my next job is to do some tests to see if it makes sense. test 1 will be to image some bright stars at very short exposures to see if the effect goes away.

I also found that diffraction patterns from bits and pieces of the OTA could be strange if the entering light column was not properly centered. You can use the reverse LED projector to test this.



Hi Asi! thanks for the feedback



Thanks Allan. I was trying to optimise the resolution, so appreciate your comment.

regards ray

[Astroman]

Fantastic scale Ray, nicely resolved. love the colours.

[marc4darkskies]

Apart from your minor guiding problems, that's a very good image Ray! Although I do tend to like more saturated colours I reckon the first one is best. Some great detail in there!! You could always blend the two. In Photoshop you'd blur the saturated version slightly and overlay it as a colour layer on top of the first and set opacity to taste to get the best of both worlds! :)

Cheers, Marcus

[E_ri_k]

Really nice image there :) Nice resolution! I like the first one.
Erik

[PRejto]

Hi Ray,

Love your images, but I do prefer #1 with a more muted colour approach. Your data sure looks "smooth!" Would you mind sharing how long your subs were and total times in LRGB? I'm working on this target too, but seem to be getting nowhere "fast" with lousy weather and getting used to new gear (ONAG + barlow on my TEC). I'm having the most trouble with RGB. Usually I try not to bin 2x2 because I don't like what it does to my smooth background in luminance (1x1). Probably I just need a lot more time in RGB to get a better result.

Anyway, I digress. I think your image is what I'm aspiring for! Congrats!

[Joshua Bunn]

Its above the image Peter, LRGB 47:60:42:52 :)

Thats a cracker of an image Ray.

Josh

[ChrisM]

Nice work Ray. Just to be difficult, I prefer the colour of the galaxy in the first pic but the background of the second pic! (It's less hazy, but I realise that that may in fact be how it is.)

Chris

[Shiraz]

Hi Andrew - Thanks


Thanks for the kind comment and helpful advice Marcus - will give it a try, although I do not currently have PS


thanks Erik


Thanks for the comments Peter. Subs were 1 minute for L and 2 minutes for the colours - total times were LRGB 47:60:42:52. I also had huge trouble with the RGB and ended up manually adjusting levels and gains so that the data was within the ranges that the auto adjust algorithms in neb and pixinsight expected - biggest problem was upper level haze and thin cloud that picked up every bit of stray light from nearby street lights and even from Adelaide at about 50k distant.
I thought that I might get away with 2x binning for the colour, but the features in M83 are small coloured features and the colour res had to be as good as the lum - hence needed a lot more time on colour than on lum. If you are using a 2x Barlow, expect to sit there for 4x as long as you would without it - looks like there is no substitute for time.


Thanks Joshua


:lol: The galaxy does not have an abrupt boundary, but slowly fades - the only way I could show that was by bumping up the background, since it seems to be difficult to see very dark transitions on the average lappy display. Thus the haziness of the background of the first image. Is this better?

Regards Ray

[ChrisM]

Thanks Ray. They say that beauty is in the eye of the beholder, and I suspect that this is most appropriate for astro pics. Looks great!

Chris

[RobF]

2nd one all the way! What an image - that really says something for your rig and the RCC, which not everyone seems to love. Top stuff.

[broca]

Splendid image Ray. I like the colors, well done!

[Shiraz]

thanks Rob. Am aware that some experienced people have reservations about the RCC, but am guessing that perhaps there were a couple that were not properly made/assembled - my limited understanding is that the more complex CCs require very tight fabrication tolerances (from the reference on Wynne correctors: "while one of the three lens elements is a simple near plano-convex or PCX, the other two are strongly curved, thin menisci, very demanding in both, fabrication and positioning/centering"). In any event, the one that I have works really well, although it required some OTA modification.

ref: http://www.telescope-optics.net/sub_aperture_corrector.htm


thanks Steve, much appreciated

Regards Ray

[Ross G]

Great galaxy photos Ray.

I love the colours in the second photo.


Ross.

[Shiraz]

thanks Ross. regards ray