Tom, Roy The UC18 (and 15 as well). Yeah the bearing arc looks like its no more than 60 degrees. What's interesting is that as far as I know, no one - until...
All the current wisdom seems settled that the edge support for a parabola disk must work EXACTLY against the calculated CoG. How large can the actual edge...
Bob: Intuitively, it would seem that one would not want them so large as to transmit compressive/deforming forces to the mirrors front surface. But, as you...
I'm looking at spider/mirror holder systems for my 18" dob (around a 20" inside diameter cage) I'm constructing. Astrosystems claims to make assemblies for...
I have a 14.5" StarStructure and love it; the eyepiece is at my eye level when my telescope is at zenith. Also the 14.5" mirror (with the mirror box that Mike...
David In the one example of both for an aprox 17" ID tube, I recall that the veins on Protostar spiders were significantly thinner. Someone chck me on this...
Thanks for your comments Joe. I raise the question because I hoped to use a very dense plastic material that should be fine. But given the weight of the...
You can learn a lot about the Protostar spiders and holders by reading their website carefully. I almost bought one once, but I learned that I could not use a...
I would like to do autoguiding with my 22" Dob (Argo Navis and ServoCAT), using PHD Guiding software. PHD supports various cameras/autoguiders, but more...
In conversation today with Protostar I was told their vanes are sigificantly thinner than any other commercially made spider. I went ahead and ordered from...
David, I have had 2 Protostar spiders, and they are thin and rigid and they are very very good, in my opinion. Regards the collimation screws, they are...
I'd stick with Astrosystems. They are made wonderfully. My Protostar is flimsy & tough to keep collimated. The plastic central bolt really turned me off of it....
I have a Protostar. I replaced the threaded rod that the allen wrench engaged in with threaded rods that have a plastic knob on the end. I got them in a...
I have to agree with Peter on the plastic central bolt. Mine striped out the threads in the sweet spot. I believe it is plastic so it will not conduct in the...
Richard, I have used AstroArt software for image aquisition and autoguiding. For a camera I stared with a Starlight Express MX 5 Cwith STAR 2000 module and...
David, you won't regret your decision. I switched from an Astrosystems unit to a Protostar unit. Protostar's system is far more refined and engineered, lighter...
Not a problem to disagree, Dick. To each his own. I still like mine, but maybe it's because I haven't found another 3-screw type with which to compare. I...
Thanks Sebastian. I was beginning to wonder if I made the wrong choice. The current models appear to be collimated with 3 screws. At least that is what the...
... PhD is ascom compliant, so it should work (assuming servocat has an ascom driver, which it very likely does). ... That's not really an issue. The question...
Hi The ServoCAT Gen2 does have a standard serial / PC port. Also it has an autoguider port as well. John ... ascom driver, which it very likely does). ... with...
As developer of the ServoCAT ASCOM driver I can offer some insight into how to use PHD Guiding software on a ServoCAT equipped telescope. All ServoCAT versions...
Sebastian, There are three mechanical problems with this design: 1) The Protostar system basically deflects a plastic bolt. The allow for deflection to...
You know, Charlie it's possible that I had an older version. I can tell this: the 3 collimation screws had to be adjusted with a philips screwdriver. What fun...
Peter, with respect, I have no idea what you are talking about in items 1 and 2. I do agree with you in item 3 that thumb screws would have been more...
Peter, Thanks very much! I have the Gen 2. Do you have to buy the cable from Shoestring as well, or are there other sources? Richard ... telescope. ... adding ...
... That's true of virtually any secondary holder. Unless you somehow make an attachment to the center of the mirror, there's no way to avoid this (and...
Hi Dick, Odd that you should mention the secondary mirror collimation issues. I have exactly that problem. It has been going on for years! I presumed it to...
Charlie, I knew it was either the spider and/or holder because I 'knew' that the mirror wasn't shifting around on the sling. This knowing admittedly was more...
There is another option. Since you are building your own 18" dob, have you considered building your own spider and secondary holder assembly? If you've got...
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