Orpington Astronomical Society

Astronomy => Technical => Topic started by: The Thing on Apr 11, 2023, 16:31:26

Title: Anti-Spike Masks for Vaned scopes. Get that refractor image look!
Post by: The Thing on Apr 11, 2023, 16:31:26
This is the latest tweak to my two vaned scopes, my 6" f4 Newt and 8" f12 Classic Cassegrain. The CC creates enormous spikes from its 1.5mm thick vanes. The shape is calculated (not by me, failed A level maths twice :roll: ) to create self cancelling diffraction patterns a bit like curved spider vanes do.

Guess which vanes have the masks and which don't!

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10050/normal_Anti-Spike_Mask.jpg)

Original version found on Thingverse and tweaked to fit my scopes in Tinkercad and 3d printed, you could cut them out of something and they would work just as well.

BTW The strange black and gray lines around the star image are the QHY294PROC CMOS overscan areas.
Title: Re: Anti-Spike Masks for Vaned scopes. Get that refractor image look!
Post by: Carole on Apr 11, 2023, 17:29:30
It's amazing these inventions.  Who would have thought shapes like that would do the job, and how did anyone find out?  Same as the Bahtinov mask - must have found out by accident in that instance. 

I have heard of this once before reading an on-line post.  Guess you're fed up with Star spikes.  I used to like them once but have gone off them.

Well done.

Carole
Title: Re: Anti-Spike Masks for Vaned scopes. Get that refractor image look!
Post by: The Thing on Apr 12, 2023, 08:18:59
When there are bright stars in the shot spikes can take over and distract from the subject. I think it's better to reduce them at source rather than battle with them later. I found that if I move the shapes towards the rim of the OTA I can have little spikes 8) if I want.