Diffraction patterns in images

[pyrasanth]

On a couple of the images I recently posted I've added star diffraction patterns- just the basic option through Noel's actions. Some people really like them but others have mixed feelings. On some telescopes you get these whether you like them or not. One could argue that the effect is artificial for both systems as one is an artefact of the optical system the other a software modification by  your design.

So, open the question to the forum- would you add star diffraction patterns to your images or are you just glad you don't have to live with them. The software introduced artefact at least gives you a choice.

[Mr Spock]

My personal choice would be to have images look as natural as possible. They aren't there 'live' so why add them / leave them in?

[PhotoGav]

Arrrgh, star spikes... I choose my equipment to ensure they are not present! I certainly don't add them in. I am not a fan.

[DaveS]

No! I dislike diffraction spikes even when they're there as a result of the optics (One reason I plan to replace my 130 PDS with a 130 f/5 'frac), I certainly wouldn't add them in post.

[Astroscot2]

I don't mind them when they are natural - the added ones are obvious to me, I hate seeing them added to images that are soft or the stars are elongated.

[michael.h.f.wilkinson]

Not a fan of them either

[Uranium235]

6 hours ago, DaveS said:

No! I dislike diffraction spikes even when they're there as a result of the optics (One reason I plan to replace my 130 PDS with a 130 f/5 'frac), I certainly wouldn't add them in post.

Youre still going to get them with a frac too

Less pronounced, but the cell clips will give you diffraction spikes on brighter stars when you are perfectly in focus.

[DaveS]

OK, my Meg 90 doesn't have any clips, and I've never seen spikes from it, even tiny ones. My new 80 f/4.4 does, I think have clips, but there're a lot of them, barely intruding. Here's a centre crop from a 1 hour [NII] stack to show such spikes as exist.

Hopefully I've now got the spacing right for the next run.

[vlaiv]

I quite like diffraction spikes in images. Real ones, not added ones :D. Don't know why, probably because when I was a kid and looked at the star images in books (encyclopedia type of books) they were usually images taken by professional astronomers using RC type telescopes (I guess), so I'm kind of used to it. It gives certain "this is how proper astrophoto should look like" feel to it. As for real spikes forming, any straight edge in optical system before convergence of rays (objective lens, mirror) will generate them. Even curved edges generate dispersion but due to them being curved light is not concentrated in straight line but halo type structure. This winter I experimented with aperture masks and fast achromat for imaging and one of the images that I made had a bunch of diffraction spikes around the brightest star. They were quite chaotic in intensity, and later on I remembered that I made aperture mask from plastic by hand and used file to shape it into a circle - clearly I didn't do a proper job

[gorann]

I agree with everyone above: if you have a system that do not generate diffraction spikes, be very happy, and if you have one that does, still be happy. But why add them? If I get diffraction spikes in my glasses (those on my nose), I find a paper towel and clean them.

[toxic]

i like them but then i have a 200P-ds so i have to but i am not going to change scopes for something as trivial as defraction spike after all, all the best images have them -HUBBLE- lol

[wimvb]

I think they can be very effectfull in certain images, e.g. star clusters. But only with moderation. I certainly would not add them.

[ollypenrice]

Often used to mask dodgy stars.

Fake ones are not offset. Real ones usually are. Note the way the vanes are attached on most secondaries.

I can, just about, live with them on long FL images. In short FL ones there is too much distraction. I bust a gut trying to keep stars down to size. This often dominates my processing workflow. The last thing I'd want to do is 'big them up.' (What a ghastly phrase. Did I really wirte that?)

Olly

[symesie04]

I quite like them, as someone above mentioned when i began looking at images of deep space they all had them and Hubble still does. I think it gives stars a real magical look and makes them look really bright which after all is what we want from stars right? Dont get me wrong no saying all images or all stars in an image should have them just maybe if there are some big dominant stars in the frame it looks nice. Seems to work especially well on those big bright blue beauties Hubble takes images of. 

Oh and just a big up for Olly yo bro your stars mash up well bling.

[matt-c]

I like the kind of one's you get by stepping down a dslr lens (with in moderation)  but I can't get away with the big cross kind. 

But to anyone who likes them I wouldn't be put off using them,  I think someone's  personal take on an image is better than  several clones of the same. 

[MartinB]

I like judicious use of star spikes in some images, they add a dynamic quality which can be missing from astrophotos.  When we observe stars they are active things, they shimmer and also they aren't constrained by 8 bit 256 levels.  What is described as a "natural image" is anything but.  Careful addition of star spikes can add some life.  Judicious is the word.