Curved spider vanes for big binos

[moriniboy]

Project for today - make 2 curved spider vanes for my 150mm Terrascan (Peter Drew) big binos.

The existing single stalk supports are very sturdy but I don't like diffraction spikes so they have to go.

[Stu]

Should be interesting, what design are you going for? Just a single curve through 180 degrees or a number of vanes?

I'm slightly confused by the 2nd image, am I being slow? [emoji3]

[moriniboy]

This is what I'm aiming for, hence the hexagonal ali bar in the second photo.

[Stu]

This is what I'm aiming for, hence the hexagonal ali bar in the second photo.

pvc large cvs.jpg

Ah yes, that makes sense. Look forward to seeing the end result

[mapstar]

Interesting project.

You will still get diffraction just not the usual 4 points of a traditional set up. I can't seem to find the link where it shows the different images for the different spider set ups.

Damian

[moriniboy]

I'm aiming for top right on this.

The project so far, just need to reduce the length of the vanes now and adjust the curvature to suit

[Stu]

Looking good. My understanding is that if you get the curvature to 180 degrees total then you will cancel out all the diffraction spikes. You still get diffraction of course but it is more of a diffuse halo around the star rather than spikes

[John]

My 12" dob has curved vanes. Diffraction is still there but it seems evenly dispersed over the FoV rather than just around a bright point. The result seems to be crisper images of stars with no spikes and I've been able to split Sirius to show the "Pup" star which I've not been able to do before.

My vanes follow something similar to the penultimate pattern of those posted above.

[mapstar]

That's something similar to what I found on the net.

Looking good should be easy to get the vane lengths right having a built in scale