Spider Vanes when observing

[Andypeck101]

I seem to be getting a cross pattern when observing stars and planets. 

The attached picture is an exaggerated version of what I see, it's much less prominent to the naked eye, but is distracting when observing. 

I did a much needed collimation this evening and everything is otherwise crisp but the Vanes gave been there a while. Any ideas on what I need to do to fix this? 

I should say this is on a skywatcher 150p dob. 

Cheers

Andy 

[DaveL59]

a feature of newts as the vanes cause diffraction spikes. Only fix would be a refractor or a MAK/SCT where the secondary mirror isn't held with a spider vane.

[Andypeck101]

Thanks for the quick reply, I could swear I didn't have them before, but the telescope has been sat idle for a while so I might be misremembering. 

 

[NGC 1502]

One solution for Newtonians is a curved secondary support.  The diffraction is still present but is spread across the field of view but is far less obvious.
 

Another (expensive) idea is to mount the secondary on an optical window, no diffraction but optical losses. My Edmund Astroscan - basically a Newtonian - has such an optical window.

The standard straight spider vanes concentrate the diffraction into spikes, curved vanes spread it out so less obvious.

Ed.

[Ricochet]

Diffraction spikes are more obvious on brighter objects. If you increase the magnification they will become less obvious.

[Starwatcher2001]

You're in good company, Hubble has the same issue.

 

[steveex2003]

Whilst I have a 250mm Dob. Possibly to my shame I hadn't looked through it for a year, preferring my 120 and 80mm fracs. A couple of months ago  i did drag the Dob out in a failed attempt to locate the Owl Comet. The two things that sprung to my attention were; where did all those stars come from, and how noticeable the diffraction spikes were not having seen them for a while.

[Andypeck101]

Yeah I've come to the conclusion I have false memories of no diffraction spikes. The view is otherwise very good with crisp stars and clear planets.

Thanks all for making me realise I'm losing my marbles

 

Andy