labtech1122 Posted February 19, 2023 Share Posted February 19, 2023 Hi, does anyone know the correct back focus for the antares x0.63 FR, ive got this focal reducer and the #93633-A celestron t adapter sc, the t ring and a canon 650d Link to comment Share on other sites More sharing options...
michael8554 Posted February 19, 2023 Share Posted February 19, 2023 At the risk of rekindling an ages-long argument about the BF of Meade, Celestron, and clone FR's: The #93633-A Celestron T-Adapter SC, the T- Ring, and Canon 650d, should give you 105mm back focus. Try that and tweak by a few mm's if it's not perfect. Michael Link to comment Share on other sites More sharing options...
michael8554 Posted February 20, 2023 Share Posted February 20, 2023 Doing my own searches, the Antares may be one of the 85mm BF items Measure the focal length by focusing the sun on an outside wall. If it's about 240mm then BF is 105mm If it's about 110mm FL the BF is 85mm Michael Link to comment Share on other sites More sharing options...
labtech1122 Posted February 20, 2023 Author Share Posted February 20, 2023 8 minutes ago, michael8554 said: Doing my own searches, the Antares may be one of the 85mm BF items Measure the focal length by focusing the sun on an outside wall. If it's about 240mm then BF is 105mm If it's about 110mm FL the BF is 85mm Michael Might be a stupid thing to say but doesn't pointing the telescope at the sun damage it? Excuse my ignorance haha Link to comment Share on other sites More sharing options...
labtech1122 Posted February 20, 2023 Author Share Posted February 20, 2023 22 hours ago, michael8554 said: At the risk of rekindling an ages-long argument about the BF of Meade, Celestron, and clone FR's: The #93633-A Celestron T-Adapter SC, the T- Ring, and Canon 650d, should give you 105mm back focus. Try that and tweak by a few mm's if it's not perfect. Michael Thats what I have been using but all my stars on the edges have rotational trails. I've managed to master up a total length of 87mm so I'm going to try that and see what happenes then buy the appropriate adapters. I can just see my self getting the adapters and not having the right ones. Measure twice, buy once haha Link to comment Share on other sites More sharing options...
michael8554 Posted February 21, 2023 Share Posted February 21, 2023 "doesn't pointing the telescope at the sun damage it? " Point the FR at the sun, not the telescope ! Only damage might be to the wall ....... 😆 Michael 1 Link to comment Share on other sites More sharing options...
labtech1122 Posted February 21, 2023 Author Share Posted February 21, 2023 1 hour ago, michael8554 said: "doesn't pointing the telescope at the sun damage it? " Point the FR at the sun, not the telescope ! Only damage might be to the wall ....... 😆 Michael Haha yea that makes sense 🤣 Link to comment Share on other sites More sharing options...
sagittariancat Posted February 21, 2023 Share Posted February 21, 2023 The back focus of the Antares X0.63 FR is i guess, 55mm. To determine the correct back focus for your combination, simply measure the distance between the T-ring and the focal plane of the camera with a ruler. This is the back focus you need to set. Link to comment Share on other sites More sharing options...
michael8554 Posted February 22, 2023 Share Posted February 22, 2023 "The back focus of the Antares X0.63 FR is i guess, 55mm." Many FRs have a BF of 55mm, which means they can screw straight onto a DSLR via a M42 T-Adapter. But these Antares /Meade/Celestron lookalikes have SCT threads, and are maybe 105mm or maybe 85mm BF, but IMO I don't think they will be 55mm BF. Michael Link to comment Share on other sites More sharing options...
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