spider vanes??

I read on cloudy nights an article on curved spider vanes vrs regular 4 vane setup on newts. My question is does anyone know who sells them(like a website) or if they are better like the article claims?
thx
Brian

There's a lot of debate on this. Basically curved vanes take the diffraction of spider vanes and smears them out evenly over the field so there's not a concentration of light in 'diffraction spikes'. It's like choosing a window that has dirt evenly distributed over the pane instead of a window with two big streaks of thick dirt on it. Actual effect on planetary contrast, etc. is also a subject of debate.

There's a spider to every taste, some possible scenarios:

3-vane straight: 6 diffraction spikes, intensity x1
4-vane straight: 4 diffraction spikes, intensity x2
3- or 4-vane curved: no spikes; though overall diffraction can be 20-50% more than same # straight-vane (depending on degree of curvature)

Someone else mentioned this, but here is a link.


http://www.1800destiny.com/telescopetubes.html


Robert W.

I've compared Mag1 PortaBall 8's side-by-side;
one with the new curved spider and one with the
older 4 vane spider. Which is best is hard to
say. The old spider has the obvious 4 spikes
on bright stars extending to large distance
across the field. The new curved version has a
faint circular smear of light right around bright stars
(not seen in the old version). Guess its a question
of where you want your spider diffraction.
The curve vanes are much thicker (4 or 5 times
thicker) than the straight ones, so I would guess
total diffracted light is greater for the curved
spider.