Fun with Diffraction Spikes!

ballaratdragons (Ken) · #1 23-05-2007, 11:02 PM

I made up a Diffraction Spike maker thingo to see if I could put Diffraction Spikes on my pics.

Anything to distract from those big blobby stars that webcams create.

I started with the old fishing line trick, but that didn't show up.

Then I tried 5mm wide cardboard stips. They only just faintly showed up on the brightest stars. So I tried 12mm cardboard stips.

Yep, works (sort of), but because the wider strips took up so much of the apature, I had to take much longer exposures. For example, the Carina image usually takes 180 seconds. This one took 300 seconds to get the same image.

One interesting thing I noticed during this experiment was that Orange stars diffract easily, whereas white ones are a let-down!!!!!

Oh well, I had fun mucking about

1. the Diffraction Spike maker thingo I made.
2. Carina with diffraction spikes
3. Antares with diffraction spikes
4. Jewel Box with diffraction spikes
5. Gacrux with diffraction spikes.

matt · #2 23-05-2007, 11:12 PM

Good work, Ken.

Those Carina and Jewel Box stars looks like crosses.

Keep pushing the envelope, mate

RB (Andrew) · #3 23-05-2007, 11:20 PM

Quote:

Originally Posted by ballaratdragons

One interesting thing I noticed during this experiment was that Orange stars diffract easily, whereas white ones are a let-down!!!!!

Maybe try different coloured cardboard.

ballaratdragons (Ken) · #4 23-05-2007, 11:31 PM

Quote:

Originally Posted by Rocket Boy

Maybe try different coloured cardboard.

Ric · #5 24-05-2007, 08:26 AM

Very nice Ken, your right though the orange stars are definitely sharper but it's an interesting effect with the white stars.

Cheers

Terry B · #6 24-05-2007, 09:34 AM

It is a curious effect.
I use the diffraction spikes on my scope to assist in focussing the CCD.You seem to have nice narrow spikes in the centre but wide ones in the upper left corner. I wonder if this is caused by the field not being flat and the focus being in a differert plane towards the edge of the frame.

h0ughy (David) · #7 24-05-2007, 10:59 AM

simply amazing Ken.

ving (David) · #8 24-05-2007, 11:04 AM

oh ken, you konw you can ad spikes in ps dont you!

hehhehe!!!

ballaratdragons (Ken) · #9 24-05-2007, 12:36 PM

Quote:

Originally Posted by ving

oh ken, you konw you can ad spikes in ps dont you!

hehhehe!!!

Vingo, I tried several ideas in PS but I couldn't work out how to do them

Nightshift · #10 24-05-2007, 12:51 PM

Being an ex-photographer I can assure you this works very well and wont change your exposure times.

Get a thin sheet of glass, (I used an old UV filter) put a tiny (and I mean tiny) spec of vaseleine on both sides of the glass, rub it all over the surface with your finger, then run your finger in a single direction over the entire surface, do the same of the other side of the glass but at right angels to the first side (hint, try different angles, gets intersting results too) If you do this correctly, the glass will appear quite clear to the naked eye, just perhaps ever so faintly "foggy", place glass in front of primary, hold it there with elastic bands or use your imagination. It wont interfere with your exposures but it will give you amazing flairing of any and all bright objects such as stars. Wash hands before before touching eyepieces.

Dennis.

ballaratdragons (Ken) · #11 24-05-2007, 01:46 PM

Quote:

Originally Posted by Nightshift

Being an ex-photographer I can assure you this works very well and wont change your exposure times.

Get a thin sheet of glass, (I used an old UV filter) put a tiny (and I mean tiny) spec of vaseleine on both sides of the glass, rub it all over the surface with your finger, then run your finger in a single direction over the entire surface, do the same of the other side of the glass but at right angels to the first side (hint, try different angles, gets intersting results too) If you do this correctly, the glass will appear quite clear to the naked eye, just perhaps ever so faintly "foggy", place glass in front of primary, hold it there with elastic bands or use your imagination. It wont interfere with your exposures but it will give you amazing flairing of any and all bright objects such as stars. Wash hands before before touching eyepieces.

Dennis.

Sounds like an interesting experiment Dennis, thanks.
When I worked in TV I was amazed to see how they used to get a soft edge effect on shows (romantic scenes, etc). They rubbed vaseline around the edges of the lens on the TV camera!!!!

Computers do it now, but it horrified me when I saw it done with vaseline.

taminga16 (Greg) · #12 24-05-2007, 05:08 PM

Ken, Another old photographers trick was to use brass fly screen wire. regards Greg.

dugnsuz (Doug) · #13 25-05-2007, 12:07 AM

Go on, rub vaseline on your cardboard you dirty old devil!!
You know you want to!
Seriously though those are serious spikes. I've tried doing them with the Astro Photoshop actions with crappy results.
Vheers
Doug
PS: Cheers even!

ballaratdragons (Ken) · #14 25-05-2007, 12:38 AM

Quote:

Originally Posted by dugnsuz

Seriously though those are serious spikes.

I have bigger ones, but thought they were too stupid to post in here

Here's a bigger set of spikes on Antares!!!

Robby · #15 25-05-2007, 01:31 PM

I use Astronomy Tools http://actions.home.att.net/Astronomy_Tools.html plugin in PS to create artificial spikes. It does a reasonable job, and gives the illusion of tighter stars.
Worth the $20 just to try I reckon!
Cheers

ballaratdragons (Ken) · #16 25-05-2007, 01:51 PM

Quote:

Originally Posted by Robby

I use Astronomy Tools http://actions.home.att.net/Astronomy_Tools.html plugin in PS to create artificial spikes. It does a reasonable job, and gives the illusion of tighter stars.
Worth the $20 just to try I reckon!
Cheers

Yep, seen that one thanks Robby.

Just gotta find the $20 to get it. Things are tight at the moment.

And the cardboard was free