Mask to remove diffraction spikes

[Stu]

I can’t recall who it was that posted about these on here, but I decided to give them a try. Someone at work has access to a 3D printer and produced them for me. Out of six, I chose the four best ones with sharpest and cleanest lines.

I fitted them today, but will have to wait until the wind and rain die down before checking out how they perform.

Anyone else tried these? I can’t even remember what they are called! 🤪

[RobertI]

Fascinating. Look forward to seeing the results. 👍

[Ags]

Quite beautiful!

[Captain Scarlet]

Tell me about the wind and rain!!

Whilst they should remove spikes, unfortunately of course they will increase the total amount of diffraction 🙁.

For stars and DSOs it should improve things  but for bright planets, unfortunately not so.

But if you can easily remove the masks, it will be interesting to hear your comparisons of with/without.

Cheers, Magnus

[Louis D]

2 hours ago, Stu said:

I can’t even remember what they are called!

Spider vane apodizers.

[Stu]

12 hours ago, Captain Scarlet said:

Tell me about the wind and rain!!

Whilst they should remove spikes, unfortunately of course they will increase the total amount of diffraction 🙁.

For stars and DSOs it should improve things  but for bright planets, unfortunately not so.

But if you can easily remove the masks, it will be interesting to hear your comparisons of with/without.

Cheers, Magnus

Thanks Magnus. Yes indeed, no such thing as a free lunch unfortunately.

These just slip onto the vanes so are easy to remove, so I should be able to compare with and without easily.

[fwm891]

@Stu Stu, take a look at David Lakehurst’s web site. He uses a single piece curved spider to reduce/remove spikes without increasing other defects.

[Stu]

Well, I did an accidental experiment tonight which proved very interesting.

I had completely forgotten I had fitted these masks to the 8” when I put it out this evening. I had a look at Jupiter and Saturn and thought they didn’t look great, blaming the seeing. The Double Double was split ok, but the star shapes were quite spikey and it wasn’t that convincing.

I popped out about half an hour ago and looked at Mars and again, it wasn’t great. Lack of contrast and just not that sharp. At that point I noticed the masks, removed them pretty sharpish and what do you know? Sharp images back! Mars looked pretty good I must say, with Syrtis Major very clear as well as the ice cap. Popping back to Jupiter, it too was much improved, much better contrast and definition.

So, as @Captain Scarlet said, there is no such thing as a free lunch! Interesting experiment but not for me! I’ll cope with the diffraction spikes 👍👍

[Louis D]

Try adding more diffraction effects with an apodizing mask.  This was Jupiter last weekend through my 6" f/5 Newtonian:

Actual home made apodizing mask:

Jupiter is overexposed to bring out the rainbow diffraction effects more clearly.

I've found it might improve contrast just a tiny bit.  It doesn't seem to reduce sharpness.  However, I rarely use it.  The psychedelic effect is just too distracting.