Friendly spiders

Oct 31

Written by:
10/31/2012 11:47 AM  RssIcon

I've been at a crossroads on what spider to build for a couple 6" reflectors I'm either building or redesigning.  I like the idea of a curved vane spider, though buying or making one is a bit more expensive or involved.  And straight vane ones don't particularly bother me, but when I do outreach, I am sometimes asked about the "spikes" near bright stars or planets.

I bought a 4 vane straight spider a few weeks ago.  It's okay - an old Meade one.  It will work, if necessary.  I'm considering building a modified version of the Royce spider, though perhaps sans adjustment screw (I'll just bend the brass tube to collimate).  I'm a believer in the KISS principle - Keep It Simple Stupid.  

The curved vane gets good reviews in general from people who use them - though it has detractors, who suggest that the diffraction is still there, merely "smeared" across the entire image.  I am hesitant because of this, but will try both to see which one is a more visual-friendly spider.

The one thing that does concern me about curved vane is that the brass I bought yesterday is only 0.025" thick.  I'll need to be careful bending a tube to collimate and avoid bending the vanes.  But I also look at it this way - that collimation is likely to stay pretty darn well and rarely - if ever - needing tweaking.  And besides, the scope I'm looking at it for - a 6" f/10.9 - will tolerate slight mis-collimation due to the long focal length.

I guess I just need to go ahead and bend the brass and start soldering.  I'll post pics.

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The Nightlight

This blog includes what to see in the night and daytime skies, thoughts on telescopes, binoculars, and other astronomy observing accessories and equipment, plus my own occasional notes on objects I've seen and observed. Oh, and the random theater or other "my take on life" post. In other words, there is always something interesting. Check it out.