· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Classic Telescopes Previous   Index   Next   Threaded   Pages: 1 starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA How old is it       #5665943 - 02/06/13 08:06 PM Attachment (53 downloads) Edit   Reply   Quote Quick Reply   Have had this a few years thought I would restore it Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: starman876]       #5665947 - 02/06/13 08:12 PM Attachment (45 downloads) Edit   Reply   Quote Quick Reply   pic of primary. stange way to hold it in place, There are holes in the side of the mirror and the clips have pins in them. Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: starman876]       #5665950 - 02/06/13 08:13 PM Attachment (29 downloads) Edit   Reply   Quote Quick Reply   pic of secondary. Little guy about an inch in diameter Post Extras:       terraclarke Pooh-Bah Reged: 05/29/12 Loc: Over the river and thru the wo... Re: How old is it [Re: starman876]       #5666078 - 02/06/13 09:44 PM Edit   Reply   Quote Quick Reply   I presume it's a true Cassegrain, (no corrector plate)? I'm guessing 1940s? Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: terraclarke]       #5666100 - 02/06/13 09:55 PM Attachment (32 downloads) Edit   Reply   Quote Quick Reply   pic of the front Post Extras:       terraclarke Pooh-Bah Reged: 05/29/12 Loc: Over the river and thru the wo... Re: How old is it [Re: starman876]       #5666102 - 02/06/13 09:56 PM Edit   Reply   Quote Quick Reply   The focuser looks like a late 50s Jaegers. Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: terraclarke]       #5666112 - 02/06/13 10:01 PM Edit   Reply   Quote Quick Reply   That is what I thought. Not sure if it original. I am trying to figure out is the way the mirror is mounted is indictave of a certain time. I have not clue when the clips with pins was only way. Every mirror clip I have seen clamps on the front edge of the mirror. This mirror has holes in it for the pins on the clips. Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: starman876]       #5666201 - 02/06/13 10:55 PM Attachment (30 downloads) Edit   Reply   Quote Quick Reply   One more view Post Extras:       Grava T Pooh-Bah Reged: 06/18/08 Loc: Quebec, Canada Re: How old is it [Re: starman876]       #5666573 - 02/07/13 07:25 AM Edit   Reply   Quote Quick Reply   The holes in the mirror clips could be there to place dollops of silicon to hold the mirror in place. Are they threaded? Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: Grava T]       #5666587 - 02/07/13 07:45 AM Edit   Reply   Quote Quick Reply   the clips have pins in them that go into the holes in the side of the mirror to hold it in place. Post Extras:       DAVIDG Post Laureate Reged: 12/02/04 Loc: Hockessin, De Re: How old is it [Re: starman876]       #5666607 - 02/07/13 08:09 AM Edit   Reply   Quote Quick Reply   The focuser is from the 1960's and is Jaegers. The mirror cell and spider are possibly a Novak again from the 1960's. The optical design is most likely a Dall Kirkham. 3-B Optical and Coulter Optics sold mirror sets. You'll need to add at least a primary mirror baffle tube or the image will be washed out with sky flooding. Also the distance from the primary to the secondary is critical. You need to measure that exact focal length of the primary and determine if it an ellipse or a parabola. From those numbers it can be calculated what the spacing should be. My guess is that it f/20 system using a 6" f/5 primary. The reason for the mirror cell design using pins to hold the primary was to not introduce diffraction from the mirror clips. Because the system is using a small diamater secondary and most likely between F/15 and F/20 someone was try to make a high res planetary scope but without the baffles the image contrast will be poor. - Dave Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: DAVIDG]       #5666633 - 02/07/13 08:33 AM Edit   Reply   Quote Quick Reply   When I reflected the light off the mirror it focused at 40 inches. Making the mirror around F6. Dpepending on the secondary magnification that could make it F20 or more. Wondering if this is a English design with the small secondary. Post Extras:       starman876 Carpal Tunnel Reged: 04/28/08 Loc: VA Re: How old is it [Re: starman876]       #5666642 - 02/07/13 08:42 AM Edit   Reply   Quote Quick Reply   Also, I have a Coulter cassegrain from that time frame and it looks nothing like this mirror. This is much older. I still ask " who has seen a mirror mounted like this before" Post Extras:       DAVIDG Post Laureate Reged: 12/02/04 Loc: Hockessin, De Re: How old is it [Re: starman876]       #5666764 - 02/07/13 10:13 AM Edit   Reply   Quote Quick Reply   I've seen amateurs use pins and also grooves along the edge to hold mirrors a number of times. The issues is that the holes need to be made in the glass before it is ground. If not because of the Tywman effect, the stress released during boring of the holes may distore the optical figure. The primary looks to be made from a Corning Pyrex "slope sided" blank that were common from the '50's into the mid 1970's. Both Coulter and 3B used them, depending on when the optics were made and they were also what was sold in mirror making kits by Edmund and Jaegers. They were most common in the 1960's. A number of ATM constructed Cassegrains were built following Novak's book on the subject "Cassegrain Notes" http://bobmay.astronomy.net/CassNotes/index.htm using commerical optics and Novak parts. - Dave Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 13 registered and 17 anonymous users are browsing this forum. Moderator:  RLTYS, BRisley  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 517 Jump to *Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Celestial Events*General Astronomy* -----   Beginners Forum   General Observing and Astronomy   Outreach   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Video and Electronically Assisted Astronomy*Astrophotography and Sketching* -----   Beginning and Intermediate Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   NEO   Planetary and Solar System Observing   Lunar Observing   Deep Sky Observing   Double Star Observing   Solar   Variable Star Observing and Radio Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Speciality Forums* -----   Arizona Science and Astronomy Expo   NEAF (Northeast Astronomy Forum) and NEAIC (Northeast Astro Imaging Conference)   AstroArt   Astronomy Clubs and Star Parties   Astronomy Software & Computers   AstroWebsites   Science! Astronomy & Space Exploration, and Others   Space Rocks   Stellar Media*Swap and Shop* -----   Shop and Swap Audio Components*CN Feedback and Vendor Announcements* -----   Vendor and Group Announcements*International Year of Astronomy 2009 - Forums are now closed.* -----   IYA Archive Info CN Forums Home

Cloudy Nights LLC Cloudy Nights Sponsor: Astronomics