Tarantula without star spikes

[Stevec35]

For those that don't like artificial star spikes I've included a version that doesn't have them which I think I like better.

Cheers

Steve

http://members.pcug.org.au/~stevec/ngc2070_STL6303_RC.htm

[bloodhound31]

Great work as usual Steve!

Baz.

[strongmanmike]

As you can see, there aren't even bright enough stars in this field to make natural RC star spikes, that's why the artificial ones looked so out of place.

Mike

[Stevec35]

Yeah - point taken Mike. I think the artificial spikes have their place but perhaps not with this type of image.



Thanks Baz

[irwjager]

Steve, that's absolutely stunning! One of those images that make you go 'oh wow' out loud as they appear on (or should I say 'pop out of') your screen.


Creating "real" fake diffraction spikes is a bit of an art and requires the right tool. StarSpikes Pro in my - admittedly biased (because I got something better :D) - opinion isn't it.

The most obvious errors people make is 1. keeping the spikes too sharp (they need a slight blurring consistent with the rest of the image), 2. not treating every source of light (e.g. all other stars) the same and 3. choosing an incorrect compositing mode for blending in the starlight (an art in itself)

More subtle giveaways are incorrect (or non existent - rays shooting out of the stars do not a diffraction pattern make) diffraction patterns for the combination of angular size of the object, focal length, aperture and general expected obstruction profile for the type of scope that's being emulated.

I did a quick modeling of a 12" RC (guessed the focal length :P: Edit: Doh! just saw F/9) and subsequent re-synthesis of the stars using the resulting point spread function (hope you don't mind Steve!).

The one error I can still see though (as in the original), is that the subtle color shift due to dispersion is wrong; it's diffracting in RGB palette but should have also been in the HST palette like the rest of the image... :rolleyes:

[Stevec35]

Thanks for your comments Ivo. I rarely use Star spikes pro - I think I pressed "buy" too quickly on my computer screen <g>. Your rework is interesting but I'm wondering now whether fake spikes are really worth the trouble.

So what tool do you use?

Cheers

Steve

[Hagar]

Very nice Steve but I am the outsider here. I like the version with the spikes. Like most images/ imagers we all have difering likes and dislikes. My opinion of the first image was the spikes highlighted the the center of the image and looked nice, sharp and clean.
Do whatever rocks your own boat, too many experts to please these days so do it for yourself.

Still a nice image even without the spikes.

[irwjager]

Yeah, it's a tough one. Personally, I do really appreciate diffraction spikes from my humble Newt as they give an extra visual cue as to the brightness, color and just general prominence/depth of a star. It's like a form of instant (but coarse) photometry. They're also helpful in discerning the properties of close together stars that would otherwise bleed into one in a single elongated star in a refractor.

Plus I grew up with the Hubble images being the absolute holy grail of astronomical imaging. :lol:

Most poorly executed fake ones do the opposite for me - they confuse - as they give me false cues; one has a prominent spike, but the other, nearly as bright, doesn't because the imager 'forgot' to put them on.

They are really distracting when they're not exactly as blurry as the rest of your real world image, because your eyes are drawn to their sharpness. You can't help but interpret that as a (false) depth cue - sort of a false depth of field effect with the sharp star being in the foreground ("more in focus").

<spruik>I use my own processing suite (www.startools.org (http://www.startools.org)).</spruik>It's got a module called 'Synth' that allows you build a virtual telescope to the desired specs. Then it uses those specs to calculate how the light would refract around the different components in your scope and applies that to every star in the image (after it has performed some basic photometry to detect all stars, their magnitude and their color).

This procedure can be abused to obtain absolutely perfect real looking diffraction spikes, but its main purpose was really to 'augment' the stars in an image so they would look tighter, brighter and more '3D'. The technique is incredibly effective on star clusters.

[RobF]

:lol: :) Too true Doug....

Great shots all of them Steve, although must admit I'm a sucker for some diffraction spikes (even if they are a showing questionable colours)

[richardo]

Hi Steve,
I much prefer this non 'spiked' version.
Definitely!

Never been a fan of artificial spikes.... at all.
Refractors trying to be reflectors:screwy:
When you first posted this, I though.... nah, what were you thinking.
But then I read you had this software, so, mmm, ok...

But you got a reflector man.... and a lovely RC at that...
Be happy for those rare times when you don't see a spike and revel in the majority of images that do...

Keep em coming.. :thumbsup:
Rich

[multiweb]

Didn't mind the star spikes too much in the original. Starspike pro works well. You just have to blend them in manually on a different layer and apply a bit of gaussian blur if needed so they don't stick out. Like what Ivo did. Then it looks natural. It's a great shot with or without.

[marc4darkskies]

Very nice image indeed Steve - wonderful detail - well done!! My vote is for the no star spikes version.

I'm working the Spider myself at the moment so will be interesting to compare.

Cheers, Marcus

[Stevec35]

Thanks for the comments guys. I guess that star spikes are a somewhat controversial issue. Marcus, I await your Tarantula with great interest. I'm sure it will be a beauty.

Cheers

Steve

[gregbradley]

Hi Steve,

Fabulous image. Such incredible central detail and those bright central stars are all individually differentiated. Terrific. I like the star spikes myself but agree they could do with subtle gaussian blur to match the seeing in the image.

Some of your stars got cut off by something during processing. A minor thing though. Alignment error?

Overall a terrific image and very high impact.

Greg.

[strongmanmike]

Ooooooh :thumbsup:...don't let us average 6"ers down now Marcus, Steve's is pretty high res ...bah! you can do it :P

MIke
ps Steve...he hasn't gotta chance (err?..do you think Marcus heard that :question:)

[Stevec35]

I think he'll do great but the RCOS maybe up for sale if a 6" produces equivalent resolution



Thanks Greg. Yeah I think there's a bit of alignment error in there which requires investigation. It doesn't show up all the time though and what with clear nights being so few and far between I'm reluctant to spend the time tracking it down.

[iceman]

This is a really beautiful image, Steve. Just the right amount of sharpness that I like.

This is now IOTW (http://www.iceinspace.com.au).

I almost chose the one with the fake spikes as I don't mind them ;)

[jjjnettie]

Congratulations on making IOTW.
Well chosen Mike.

[Stevec35]

Thanks very much Mike! Nice to get one of these.

[Stevec35]

Thanks very much

[Ric]

A wonderful image Steve and congratulations for IOTW.

The colours are quite stunning.

Cheers

[Stevec35]

Thanks Ric!

[Stu Ward]

Looks just like the APOD on the Nasa website for 11-1-11
Congrats

[Stevec35]

Thanks Stu!

[Paul Haese]

Nice work Steve, did this one myself a few years back but would like to try this very type with the hubble palette that you have here as an incorporation with the LRGB data. Your image is well detailed and looks nice and sharp. I don't care one way or the other about diffraction spikes, both look fine to me.

[Stevec35]

Thanks Paul. There are so many variations of blending that you can use with the Tarantula but you have to be careful that you don't wind up with a confused mess of colour that isn't aestetically attractive.

Cheers

Steve