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Diffraction Spikes, Yes or No

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11 replies to this topic

#1 NoDarkSkies

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Posted 15 January 2022 - 12:36 AM

So being cloudy tonight I thought play with Star Diffraction Spiking.

I went ahead and bought StarSpikes Pro 4 tonight being it was the only Application I could find online.

Bummer that MaxIm DL 6 has no tool or add on to do this Diffraction Spike process, or at least I have not found a way.

 

While I like some and not others it seems unreal or not natural for me.

My Astro Star Spikes Album and Full Size Images.

 

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Being new to Astrophotography what do other new comers think about Diffraction spikes?


Edited by NoDarkSkies, 15 January 2022 - 12:37 AM.


#2 Stellar1

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Posted 15 January 2022 - 12:43 AM

First off these are great images! as for diffraction spikes, I do like subtle spikes on stars but definitely not off the core of galaxies, that doesn’t look right, distracts from the galaxy. It’s a funny thing cause they work on some images but not others, I didn’t think I’d like them on areas of high stellar concentrations but on that last image it’s growing on me, maybe a tad smaller spikes, sure is a beautiful image.



#3 DirtyRod

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Posted 15 January 2022 - 12:47 AM

Agree. Great images and sometimes light spikes can add something to a great image. Too many and it looks a bit too much like fantasy. Starts to remind me of the original Star Wars poster. 


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#4 sharkmelley

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Posted 15 January 2022 - 12:56 AM

While I like some and not others it seems unreal or not natural for me.

Agreed.  The diffraction spikes in those images look totally artificial.  The reason they look artificial is the lack of colour variation in the spikes.  Spikes caused by diffraction have a pattern of colours caused by the fact that each wavelength of light diffracts differently.

 

Mark


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#5 acrh2

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Posted 15 January 2022 - 01:09 AM

Startools has Synth module which is a full optics simulation of the diffraction spikes, down to the nuts and bolts that hold mirrors together.
Can simulate reflectors or refractors.
https://www.startool...g/modules/synth
 

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#6 Oyaji

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Posted 15 January 2022 - 01:22 AM

Interesting. From my perspective, diffraction spikes are a necessary evil of certain scopes, mainly scopes with spider vanes. So the answer is:  yes and no.

 

Does anybody know of software that gently removes such diffraction spikes without adversely affecting the rest of the image?  If there is, I'll install it tomorrow!  


Edited by Oyaji, 15 January 2022 - 01:25 AM.


#7 Mike in Rancho

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Posted 15 January 2022 - 01:26 AM

I like 'em if they're real!  If you want them with a refractor though, I'd at least lean towards semi-real, by sticking something on the dew shield.  One protrusion will create a spike on both sides.  Another 90 degrees off will create a typical 4-vane Newt appearance.  Wires all the way across would also work.

 

The ones generated here are both too perfect and too flawed.  And too prolific.  Mark beat me to it, but the spikes are actual diffraction, so if bright enough you should get a rainbow-like effect.  I presume if someone knew how to analyze the spikes, it would be real spectral information about the star.

 

Here's a deep crop on Hatysa next to Orion, taken this month.  Pardon the crudity here, as I am still working out massive gradients due to my quite light-leaky new Newt, along with some seriously funky star shapes caused by the MPCC.  But the color diffraction is obvious, and can just be seen even on the smaller spikes of the dimmer stars.  Oh also I clearly need to get my vanes straight and in line with each other, but that's another dose of reality compared to the too-perfect false spikes from that program.  My image also doesn't show any spikes from the Trapezium.  Likewise, a recent integration on M81 shows no spiking of the galactic center.

 

M42 deep crop on Hatysa ST8 1C.jpg

 

Startools does in fact have a module that can create more accurately-modeled diffraction effects of both Newts and refractors, with a load of options even down to screws, mirror clips, secondary size, and focuser protrusion.  It's just art if you were to include them in a final image, and in discussing it recently the purpose of the module was actually to help teach PSF's.

 

 



#8 acrh2

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Posted 15 January 2022 - 01:33 AM

 

Being new to Astrophotography what do other new comers think about Diffraction spikes?

 

Diffraction spikes are an iconic feature of astrophotography.

 

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#9 TOMDEY

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Posted 15 January 2022 - 03:54 AM

Well... it's cute and all, kinda like a Barbie Doll face vs an actual human face. I can see where the software would be pretty easy to compose. It would be more believable of the user could dial in a clocking angle that is not impeccably-aligned with the array coordinates. Here's my submission of real diffraction spikes. Altair taken with my 12.5-inch F/6 Newt with an off-axis guider prism, mirror clips, etc. in the pupil function. Note that by far >>> the biggest diffraction source in any telescope is the edge of the mirror or lens. Just because we give it the name ~Airy Disc~ doesn't prevent it from being the dominant source of diffraction present in the image.    Tom

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  • 75 Toms Altair - click-click.jpg

Edited by TOMDEY, 15 January 2022 - 03:55 AM.


#10 17.5Dob

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Posted 15 January 2022 - 04:29 AM

In the OP's post, I think the diffraction spikes are somewhat tolerable on the the two open clusters, but look terrible on the galaxies. but to the OP, instead of of the totally artificial look of having the spikes straight horizontal/vertical it looks a bit more natural if you rotate your image some arbitrary amount before applying the spikes, then rotate it back...

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#11 NoDarkSkies

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Posted 15 January 2022 - 10:28 AM

Like this?

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or this

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Edited by NoDarkSkies, 15 January 2022 - 10:34 AM.


#12 nyairman

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Posted 15 January 2022 - 01:39 PM

To each their own. I agree with the comments. Done tastefully, software generated star spikes add to an image, especially in printed media.


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