· 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 >> ATM, Optics and DIY Forum Previous   Index   Next   Threaded   Pages: 1 Messyone super member Reged: 05/02/12 Loc: Down Under Objective diameter       #5535706 - 11/23/12 03:11 PM Edit   Reply   Quote Quick Reply   Hi, Does anyone know the diameter of a 150mm Synta refractor lens....that is just the glass. I'm thinking of replacing the lens of my 6" f8 with an Istar f8 R30, that has the diameter of 154mm. A friend has recently done this with a 127mm lens. He replaced the old Saxon lens (think Saxon are made by Synta) with the Istar one. The glass was exactly the same diameter so he didn't need to muck about with fitting the Istar cell to the Saxon tube...just used the saxon cell. If I can use the Synta cell with Istar lens that would be brilliant. So if any body knows I'd love to know. I'm a bit reluctant to pull mine apart just to measure it. Thanks. Matt Post Extras:       Mirzam Post Laureate Reged: 04/01/08 Loc: Lovettsville, VA Re: Objective diameter [Re: Messyone]       #5535958 - 11/23/12 05:59 PM Edit   Reply   Quote Quick Reply   Although your friend apparently was successful in his lens swap, there are risks in using a cell other than the one supplied by the lens manufacturer. You need the lens elements to be held securely enough to maintain centering, but not so tight as to become pinched by temperature changes. A properly designed cell is an important aspect of ultimate lens performance. Unfortunately, this aspect does not always receive enough attention. Personally, I think you should try to adapt the cell to your existing tube. Ask Istar to provide the dimensions of their cell and get an adapter ring machined if necessary. JimC Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 14 registered and 25 anonymous users are browsing this forum. Moderator:  ausastronomer, richard7  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 294 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

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