A colorful Tarantula Region, new version (see post)
Hi all, I have just uploaded a new image with my new OTA in Coona.
It is another classic, the region around the Tarantula Nebula.
This should have been my "first light" since I started collecting the Ha signal as the new rig was up and running, but for several reasons I have processed it only recently.
Hope you will like, still same issues I am investigating on the fat FWHM (seeing quite so-so, plus probably some issues with the focus), however the final result looks quite pleasant to me.
Comments and critics as usual are welcome.
Clear skies
Marco
Excellent image of a dynamic field Marco. Your colour processing is remarkably consistent, the colouring here is almost identical to your previous shot of the region with the TEC140, you must have a disciplined work flow
A wonderful wide and colourful field. A lot of tight small stars there so not sure what the fat FWHM you are referring to is here.
The top right corner stars look a hair out of focus compared to the other 3 corners so a very small amount of tilt.
Also with these scopes, focus will shift despite carbon fibre once the mirror achieves the same temperature +/- .5C. So if you focus when you start and the mirror hasn't achieved equilibrium then you will need to refocus once it does. In my case that takes about an hour.
I also use temperature compensation in case focus shifts with temperature drops. That may not be so critical with a carbon fibre scope but the first is.
Hi Marco,
As you know I'm a huge fan of your work - but unfortunately not of this image.
To me it looks very HDR in the core region, too flattened and there's no dynamic range. Maybe it's just me agreeing with Dr. Malin in this case, but to my eye the brightest part of a nebula should appear, well bright!
Wonderful tight stars and the colours are lovely though!
Looks pretty good to me Marco. Lovely colors and good details.
Thanks Marc!
Quote:
Originally Posted by Tony_
Great image Marco - good to see you back!
Thank you Tony
Quote:
Originally Posted by strongmanmike
Excellent image of a dynamic field Marco. Your colour processing is remarkably consistent, the colouring here is almost identical to your previous shot of the region with the TEC140, you must have a disciplined work flow
Thank Mike. I have the same processing routine on all my images. In fact the color of the brightest regions (as well as stars) is actually coming mostly from the calibrated RGB image, as it represents the best "reality" IMHO, I just blended in the higher contrast luminance signal coming from Ha and OIII. The faintest regions on the other side takes signal (and therefore color) mostly from the narrow band stacks. I make sure when I combine the NB that the actual color result is consistent with the RGB, to keep the overal feel "natural". I did the same on my older TEC140 image, which, despite having a bit less resolution (yet the Rifast is seeing limited here) and wider field of view, shares a similar overall color balance. Having said that, talking about colors in astronomical images is always a bit of a stretch, since actual "real" colors do not exist
Quote:
Originally Posted by gregbradley
A wonderful wide and colourful field. A lot of tight small stars there so not sure what the fat FWHM you are referring to is here.
The top right corner stars look a hair out of focus compared to the other 3 corners so a very small amount of tilt.
Also with these scopes, focus will shift despite carbon fibre once the mirror achieves the same temperature +/- .5C. So if you focus when you start and the mirror hasn't achieved equilibrium then you will need to refocus once it does. In my case that takes about an hour.
I also use temperature compensation in case focus shifts with temperature drops. That may not be so critical with a carbon fibre scope but the first is.
Hi Greg, thanks. The FWHM is overall higher than 3" (in particular in the RGB), that is why I had to pay a lot of attention during the stretching to avoid getting the RGB stars becoming too "fat", even if you can still see it, in particular on the clusters. Deconvolution helped but not enough. I agree on your suggestions on the temperature compensation, even if I am actualy focusing every hour. What I am considering now is adding an external Atlas focuser (to install in a field trim in the coming months) in order to get a better sampling of the very narrow critical focus zone. This may help a bit improving the sharpness. Tilting I can adjust remotely, I have already did some tuning, unfortunately with the bad weather and smokes of last weeks I couldn't really test it but I am confident to fix it properly soon.
Quote:
Originally Posted by Andy01
Hi Marco,
As you know I'm a huge fan of your work - but unfortunately not of this image.
To me it looks very HDR in the core region, too flattened and there's no dynamic range. Maybe it's just me agreeing with Dr. Malin in this case, but to my eye the brightest part of a nebula should appear, well bright!
Wonderful tight stars and the colours are lovely though!
I Andy, fair comment. It is always a difficult balance to keep on these high dynamic range fields, I more or less compensated the brighter parts of the nebula in a similar manner as I did it in my larger fov with the TEC140, however point taken, keeping a bit more brightness difference may improve the overall look of this area..
Thanks again to everybody spending time to comment the image
Clear (and not smoky) skies
Marco
Hi Marco,
I really like your rendition. I like the way you have rendered the dynamic range with light areas as they are, I think the overall effect is very natural and pleasing and as always your colour is spot on.
The stars don't look bloated at all to me, so you have processed very well with RGB seeing at >3" FWHM.
Hi Marco,
I really like your rendition. I like the way you have rendered the dynamic range with light areas as they are, I think the overall effect is very natural and pleasing and as always your colour is spot on.
The stars don't look bloated at all to me, so you have processed very well with RGB seeing at >3" FWHM.
Cheers,
Tim
Thanks Tim, happy you like it. I am debated too, perhaps a bit less contrast compression would improve the image as per Andy comment, I will give it a try within a couple of days to see if this is the case or not
Regards
Marco
Hi Marco,
As you know I'm a huge fan of your work - but unfortunately not of this image.
To me it looks very HDR in the core region, too flattened and there's no dynamic range. Maybe it's just me agreeing with Dr. Malin in this case, but to my eye the brightest part of a nebula should appear, well bright!
Wonderful tight stars and the colours are lovely though!
Overall the image is ecstatic but I did also feel those centre bright stars in the Tarantula which are some of the largest stars known are not bright enough as they are extremely bright in real life.
A very minor point though in an overall spectacular image but its probably the small difference between a spectacular image and a perfect image.
Composition is quite pleasing and the detail is superb as I would expect. Is this about 50% resampled? Or is is more? I agree with Mike that the colour is similar each time for your images. Looks to be a nice scope you have there.
Hi Marco,
that's a top picture.
I agree with others that it needs some selective contrast adjustment in the brightest core area.
How did you process it?
I bet you used PixInsight & Photoshop?
I think it looks great, Marco! Amusingly I'm often a bit sensitive to images that look tonally flat (usually due to heavy-handed HDR), but I wasn't bothered at all by this image... each to their own I guess.
Nice picture, but how did you get this from light polluted Singapore ?
Thanks!, The image was taken under the dark skies of Coonabarabran where I have my remote observatory, surely not from singapore where I can see stars of 2.5 mag at best the few nights the sky is not clouded
Quote:
Originally Posted by gregbradley
Overall the image is ecstatic but I did also feel those centre bright stars in the Tarantula which are some of the largest stars known are not bright enough as they are extremely bright in real life.
Quote:
Originally Posted by Peter Ward
A good rendition, but I have to say I agree with Andy. The brightness of the core is too compressed.
Quote:
Originally Posted by alpal
I agree with others that it needs some selective contrast adjustment in the brightest core area.
Thanks all for the comment, I have uploaded another version with less compression of the total dynamic, probably still not perfect but it probably render a bit better the high tone difference of this region including the Tarantula core..
Please let me know what you think, I believe this is getting closer to a good compromise, providing the target to have both dim and bright areas equally visible without burning out (and loose color saturation) on the nebula core..
Quote:
Originally Posted by Paul Haese
Composition is quite pleasing and the detail is superb as I would expect. Is this about 50% resampled? Or is is more? I agree with Mike that the colour is similar each time for your images. Looks to be a nice scope you have there.
Thanks Paul. if you click on the image (on a desktop) you can see the full resolution (the full res image is about 3900 px per side), otherwise the window is dynamically stretched to fit your screen.. Alternatively you can click on the image and open it on a new window on the browser or you can download it, in both case it will be at full res
Quote:
Originally Posted by codemonkey
I think it looks great, Marco! Amusingly I'm often a bit sensitive to images that look tonally flat (usually due to heavy-handed HDR), but I wasn't bothered at all by this image... each to their own I guess.
Thanks Lee, as I wrote above I also agreed with Andy, therefore a new version is now on the site (for a while, than will remove one of the two, probably the older one). It is always a difficult business to image these area and keeping the result natural while trying to highlight both bright and dark zones
Thanks again everybody for the comments, appreciated
Clear skies
Marco
How did you process it?
I bet you used PixInsight & Photoshop?
Hi Allan, yes, I used mainly PixInsight and PS.
In PI I do all the preliminary work on the stacked fits (Color combination and calibration, deconvolution, background removal, non linear stretching, star reduction, noise removal etc), in PS I combine the Ha/OIII on the RGB and do all the other cleanup and final touchings..
Cheers
Marco
tough crowd.
