{"product":{"product_id":"B07CSJZS1M","title":"Gosky M42 Extension Tube Kit for Cameras and Eyepieces - Length 7mm 10mm 20mm 30mm","price":null,"image_url":"https://m.media-amazon.com/images/I/21rte9Eg6YS._SL500_.jpg","url":"https://www.amazon.com/dp/B07CSJZS1M"},"comments":[{"body":"so at f/5 with a Barlow would push to f/10 or double the 650mm focal to 1300mm, or both? i'm so not good at the math on this stuff. \r\n\r\nif i'm getting roughly 10mm at 1300mm that's 130x but when i used that caclulator it was like 94.xx-ish iirc. if i could figure out hot to get it to around 50-60x i could get a full disc in my area for certain.\r\n\r\ni ordered [these](https://www.amazon.ca/dp/B07CSJZS1M/ref=cm_sw_r_cp_apa_glt_i_1EMH763D42W47044RV1C?_encoding=UTF8\u0026amp;psc=1) which i am winging will help. usually with a 23mm Aspheric EP or 26mm Plossl EP i'm getting full discs but at distance, add a 2x Barlow and i'm nice and close but still a full disc as my reference picture in either this or another post (sorry if it's not this one) shows.\r\n\r\ni'm super new to the camera thing, and i just kind of got the hang of the phone camera thing, but i'm a full throttle kinda guy with a lot of time on my hands and always a question i figure is just outside my intellectual quotient. hahaha\r\n\r\nhence asking you fine people. :)","subreddit_name":"telescopes","author":"redeyzbadman"}]}