Double diffraction spike on Newtonian

[Stefan12]

Hello,
I have a 10 inch ONTC Newtonian and noticed I'm getting a double (split) diffraction spike on the right spike.The Newtonian has a TS double vein spider on the secondary mirror. Because the spider veins are so thin, I wonder whether one is slightly twisted?!
Any ideas?

I've attached a couple of images

Cheers

[Startrek]

Yep possible spider vane issue or to a lesser extent secondary alignment issue
That’s why I didn’t buy the ONTC ( premium scope )
Instead I opted to buy the Klaus Helmerich Carbon tube separately and fit my own GSO hardware ( single blade spider vane )
I’m assuming yours is an f4 which is more sensitive to spider vane alignments / reflections than my f5 scopes
Looks like some fine adjusting and testing required over a few nights

Cheers
M

[Shiraz]

maybe check that the spider vanes form straight lines from one side of the ota to the other (check by eye with a ruler for reference). If the secondary is slightly offset from the centre, you may get spiders on each side of the secondary that are not parallel with each other and will give two different diffraction spikes (eg the vertical vanes in the rough illustration attached).

cheers Ray

[bojan]

That is definitely the cause of double spike. I also have that and it doesn't bother me at all.

[atalas]

Yes I believe Ray right :thumbsup: won't be such an easy thing to correct If the mounting holes are out of square.