Diffraction spikes for my ED80

[iceman]

Hi all

I'm a fan of diffraction spikes, and would like the option of adding some to my widefield imaging through the ED80/350D.

What's the best way of making some sort of fishing line arrangement that I can put over the objective end of my ED80 to achieve this?

How thick should the fishing line be? What size does the holder need to be to fit around the dew-shield of the Saxon ED80?

Suggestions welcome.

[monoxide]

you could make up the same kind of arrangement as a cardboard solar filter, 20lb fishing line is probably comparable to the thickness of the spider in a gso newt.

since the fishing line is fairly transparent i'd give it a quick rub with wet + dry paper and spray the whole thing black because i've noticed in some of the shots that people have used fishing line it kind of works like a prism making the spikes rainbow coloured

[RB]

A quick and easy way is to use blu-tack and stretch the ends over the dew shield.
I'd recommend using fine black fishing string to avoid the rainbow effect that clear fishing line creates, unless that effect is desirable.

[iceman]

.. and a protractor to ensure my angles are 90° :)

Thanks guys. RB yours sounds quick and easy, might go that route for now. Cheers.

[RB]

That's what I did since I wanted to try things out first.
It's not to difficult to get them at right angles and it won't show up if they're not perfectly 90'.
This also gives you an easy way to try different thicknesses before committing to a permanent frame later if you want.

[GTB_an_Owl]

you might also try your fishing line and a thick rubberband instead of the blu-tack Mike

geoff

[wavelandscott]

Permanent Marker on the glass...;)

I think the blu tack sounds like the real winner...

[Garyh]

How about the top cover of a 25 or 50 cd stack for a cap. They already (most) have 4 holes or notches at 90 degrees. Just cut the flat top off and sticky tape your fishing line to the holes. Then you can just drop the hole thing over your dew cap and use a little blu-tack to hold it or just sticky tape?
Maybe something elastic for the difraction spikes like thin black hat elastic would work a treat for this?

cheers Gary :thumbsup:

[g__day]

Or simply use Photoshop CS2 and a astronomy marco to add diffraction spikes!

[OneOfOne]

I have to admit, I am not a fan of difraction spikes for visual use and find them very annoying....in fact one of the reasons I bought the SCT! But photos without them seem to be lacking something! They seem to add character to star images.

[RB]

I must admit I'm not a fan of software created diff. spikes at all.

If I was to image through a refractor/SCT and wanted to create spikes then I'd use the string method and even then it would depend on the actual object being imaged.

[Geoff45]

Hi Mike
Personally, I think that one of the great things about a refractor is that they don't show diffraction spikes. However, if I was going to put them on stars I'd go the photoshop method. That way you keep your options open and get two pics for the price of one. Noel Carboni has some astroplugins here (http://actions.home.att.net/Astronomy_Tools.html)that will do the job.
Geoff

[iceman]

I agree that diffraction spikes are not for everyone, and probably not for every object.

But I like them, and on bright stars I think they look great. I'd much prefer to use fishing line method as opposed to the software version - i think they look more natural.

[davidpretorius]

i like the black marker option.........how cool is that??

and then if you make a mistake, just rub it off with your finger.............after you have eaten greasy chicken :D

[EzyStyles]

:lol::lol::lol::lol: hey its permanant :)

Yes the fishing line does the trick but it makes the diff spikes not as thick as newts.

[DaveM]

Just wondering if anyone adds more than the standard 4 spikes? Presumably you could do 6 or 8 for a really funky image.