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After the last little flurry of interest in making a "metal mirror" I have bought a couple of nice chunks of 9" diameter billet alumin(i)um for an attempt at...
Hi Steve, After the last little flurry of interest in making a "metal mirror" I have bought a couple of nice chunks of 9" diameter billet alumin(i)um for an ...
Hi Ned, Could you elaborate on mounting and using a green laser as a "Finder Scope"? I have seen green laser pointers on the Net for $10. Telescope sites...
What alloy are you using? 6082T6. Its age hardening, so it can be strengthed after machining by heating it just right. Quite how, I haven't determined yet ! ...
Hi Umesh and Brian, Thanks ever so much for your excellent presentations at the Portland IV Workshop. As expected, you got plenty of feedback, and were able...
Greetings, If I were trying this, here's what I would do: 1) Use a cast aluminum blank, like MIC-6 because of its low stress characteristic. 2) Mill the back...
Hi Steve, I thought Dave Rowe's suggestions were really good. Cheers, Russ In a message dated 8/4/2010 5:44:20 A.M. Hawaiian Standard Time, smtaylor@......
... I'll try it and see what 6082 can do. Otherwise, I'll do what you suggest, and get some technique going first. I'm still interested in the best ways of...
Hello Umesh and Brian, Your presentations were very interesting. Thank you for coming to Portland IV. We hope that you succeed with your program as it will...
Hi Bruce, Dave, David, Drew, Chuck, John, Tong, Kiran, Peter, Josh, and Richard, I'm gradually working through a long list of follow up items from the Portland...
Hey guys, Hi Drew, I want to pleed the case for fast spherical mirrors again. Now that I have made a few parabolic mirrors I can tell you they suck. I can...
Hi Drew, Why does it have to be from off-the-shelf lenses? In quantities of 10 or more, custom lenses can be inexpensive compared with the cost of all the...
Hi Drew, I did look into plastic lenses made by places that make lenses for spectacles. There are a number of materials with different refractions and ...
Hi Dave and Drew, This is an excellent conversation. I must admit that custom lenses are looking better and better. So after 4 inches things get more...
Dave, Thanks for taking up the challange. I was so hoping you would. I am way out of my leauge on this optical stuff and you know it. You designed my...
Hi Drew, With a fast spherical primary and modest aperture corrective lenses, I think one has to be modest in expectations, more ST7 camera field size and...
Hi Drew, That should be much more reasonable. Perhaps this question could be put in reverse. For a 1 m f/2.5 (or f/3) telescope with a spherical primary, ...
Dear Andrea, Thanks for sending me your paper on "The TIRGO Lunar Occultation Program." This 1996 paper with an aperture (diaphragm) "one pixel" detector...
While we are talking about spherical optics, I might mention I own one of these (only a 10") "Newise" designs http://www.astro.cardiff.ac.uk/observatory/chant/...
Dave Rowe, Can we do this for f/2.5 or f/3 big mirrors ??? It seems the problems were in alignment. If the final design allowed for adjustment of the...
... Why not ask Peter Wise - He's always very helpful to me when I've needed a hand with it ? He now runs http://www.zerochromat.com I'm sure Peter will be...
Hi Steve, I presume the front plate is just a flat plate? It looks like a three element design, with two before the Newtonian secondary, and one after the ...
Hi Drew, Great job on helping to give all spherical telescopes serious consideration. Much appreciated! Personally, I think that a partially parabolized...
Hi Andy, Many thanks for the reference to Roger Angel's 30 meter design. I have seen this design before. The main problem with it is the two aspheric...
Hi David, Attached is my talk from Portland. Pages 38-43 have some corrector designs Dave, Tong, and I devised. There are several two-spherical element...
Hi Peter, Thanks very much for a very helpful input. One of the things that is becoming clear is that for smaller telescopes (and I would probably include 1...
Hi Dave, Not only am I warming to custom spherical lenses, but also to secondary mirrors, especially if spherical and concave. Cheers, Russ Hi Peter, There...
Scheduled Maintenance:
We are undertaking some essential, but extensive maintenance to improve Yahoo!
Calendar. Your Group Calendar is being migrated to a much improved version of
Yahoo! Calendar. During the maintenance period, you may not have access to your
Groups Calendar.
We sincerely apologize for this inconvenience. Your Groups Calendar is in great
shape and we are working to have it available again as quickly as possible
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