https://ontariotelescope.com/blogs/blog/zwo-duo-cameras-and-compatible-image-circles 2026-07-31T12:30:34-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogzwoduofeatured_914b6b4c-7a24-4aff-a3ce-9dccdd24f3c5.png?v=1785515412 ZWO Duo camera's and compatible image circles ZWO Duo and Air cameras: the guide sensor sits outside the APS-C sensor, so the telescope needs a larger image circle https://ontariotelescope.com/blogs/blog/navigating-optolong-filters-lenhance-lextreme-and-lultimate-for-astrophotography 2026-07-31T12:29:34-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogoptolongfeatured.png?v=1785515374 Navigating Optolong Filters: L-eNhance, L-eXtreme, and L-Ultimate for Astrophotography Optolong L-eNhance, L-eXtreme, L-Ultimate and L-Quad Enhance filters plotted against the Bortle sky brightness scale https://ontariotelescope.com/blogs/blog/may-2025-the-night-sky-this-month-galaxy-season-wraps-up 2026-07-31T12:29:59-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogmay2025featured_c75d2c06-895d-4b44-8430-4e4f0cb1237f.png?v=1785515399 May 2025 The night sky this month. Galaxy season wraps up. May 2025 night sky calendar: Mars meets the Beehive, the Eta Aquariid peak, the four moon phases and the dark-sky window https://ontariotelescope.com/blogs/blog/choosing-the-right-telescope 2026-07-31T12:30:01-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogtelescopefeatured_b56e0d7c-e69b-43d6-b72f-bfe688e04add.png?v=1785515401 Choosing the Right Telescope: Understanding RC, SCT, Newtonian, and Refractor Designs for Astrophotography Ritchey-Chretien, Schmidt-Cassegrain, Newtonian and refractor telescope designs ranked from narrow field to wide field https://ontariotelescope.com/blogs/blog/capturing-the-california-nebula-a-guide-for-astrophotographers-c741b6 2026-07-31T12:29:36-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogcaliforniafeatured_e211de2b-3932-4d86-9d73-1b61c0c1aa44.png?v=1785515376 Capturing the California Nebula: A Guide for Astrophotographers Framing the California Nebula: its 2.5 degree long axis inside APS-C fields of view at 300mm and 400mm https://ontariotelescope.com/blogs/blog/fall-astrophotography-unveiling-the-hidden-gems 2026-07-31T12:29:38-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogfallfeatured.png?v=1785515378 Fall Astrophotography: Unveiling the Hidden Gems Fifteen autumn astrophotography targets grouped by what each one requires: wide field, long focal length, filters, long exposures, dark skies or tracking https://ontariotelescope.com/blogs/blog/summer-sky-objects-you-dont-want-to-miss 2026-07-31T12:37:22-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogsummerfeatured_3986db6d-4f07-45c4-9374-94b8db96601e.png?v=1785515842 Summer sky objects you don't want to miss! Pre-dawn summer sky: hopping from Saturn to the Great Square, Fomalhaut, Neptune, Mars, Hamal and Jupiter using fist widths at arm's length https://ontariotelescope.com/blogs/blog/the-power-of-precision-bahtinov-focus-masks-in-astronomy 2026-07-31T12:30:14-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogbahtinovfeatured_87b66eae-adbb-4292-8bee-888e815041ed.png?v=1785515414 The Power of Precision: Bahtinov Focus Masks in Astronomy Bahtinov mask focusing: the centre diffraction spike shown offset inside focus, centred at focus, and offset outside focus https://ontariotelescope.com/blogs/blog/controlling-your-wanderercover-flat-panel-with-asiair 2026-07-31T12:30:03-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogwandererfeatured_6fcb9848-3970-4660-ae31-ce96f9b6bd45.png?v=1785515403 Controlling Your WandererCover Flat Panel with ASIAIR Controlling a WandererCover flat panel from ASIAIR by switching the DC port: timing windows and preset brightness steps https://ontariotelescope.com/blogs/blog/what-is-back-focus-astrophotography-reducer-flattener-spacing 2026-07-31T12:36:22-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogbackfocusfeatured.png?v=1785515422 What Is Back Focus in Astrophotography? Telescope Reducers, Flatteners, and Spacing Explained A 55 mm back focus imaging train: spacer 16.5 mm, filter drawer 21 mm and camera sensor depth 17.5 mm, measured from the rear of the reducer https://ontariotelescope.com/blogs/blog/d-size-vs-v-size-a-complete-guide-to-telescope-dovetail-systems 2026-07-31T12:30:17-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogdovetailfeatured_c0d732c5-0ac1-4ecc-b555-3135ee10708d.png?v=1785515417 D-Size vs V-Size: A Complete Guide to Telescope Dovetail Systems V-size Vixen and D-size Losmandy dovetail bar profiles compared to scale, about 44 mm against 75 to 84 mm https://ontariotelescope.com/blogs/blog/guide-scope-vs-off-axis-guider 2026-07-31T12:30:05-04:00 weekly https://cdn.shopify.com/s/files/1/0686/0049/6239/articles/blogguidingfeatured_09b94c60-fd39-4131-a656-cae85901f1b4.png?v=1785515405 Your Guide Graph Is Lying to You Guide scope or off-axis guider: a PHD2 guide graph reporting 0.41 arcsecond RMS beside elongated stars from the same night