Telescope Optics Calculator

Telescope calculator: calculate eyepiece magnification and exit pupil from your own optical dimensions. Enter aperture, telescope focal length, eyepiece focal length and optional apparent field. See magnification, exit pupil, approximate true field of view, native focal ratio and the conventional Dawes estimate.

USEFUL FROM THE START
• All five base calculations in Free.
• Two named telescope profiles and two named eyepiece profiles, with notes, search, edit, duplicate and delete/Undo.
• Decimal millimetre or inch input, with optional apparent field when unknown.
• Visible formulas and assumptions, plus light, dark and system appearance.
• Text and CSV result export, sharing and JSON library backup/restore in Free.

OPTIONAL LIFETIME PRO

One optional, nonconsumable Google Play purchase adds more profiles without the Free profile cap, side-by-side comparison using shared or independent telescopes, custom Barlow/reducer factors, and named calculation or comparison scenarios. Saved scenarios retain their original inputs when equipment is edited or deleted. There is no subscription. Google Play shows your regional price before payment; restore purchase access with the owning Play account.

YOUR EQUIPMENT, YOUR COPIES

Core calculations and local records work offline. There is no PatchMedia account, advertising, equipment catalog or cloud record sync. Profiles, notes, working calculations, scenarios and settings stay in app-private storage during normal use. Google Play handles purchases and can process technical Billing diagnostics. Selected document providers and share recipients handle files you choose to send.

JSON includes profiles, saved scenarios and settings, up to 10 MiB and 10,000 records per type. It excludes working calculations and purchase evidence. Restore previews the file, then replaces local records/settings and resets both working calculations after confirmation. Keep a JSON backup before uninstalling or changing devices. Purchase restoration is separate and may require a connection. Existing saved scenarios remain readable, exportable and deletable if Pro access changes.

CLEAR LIMITS

True field is approximate and depends on field stop and equipment. Dawes is a conventional estimate, not a guarantee of visibility or resolving performance. This manual geometry calculator does not provide sky maps, simulated views, observing or gear recommendations, imaging/exposure tools, manufacturer fitting tables or guaranteed compatibility.

Privacy: https://patch-media.com/privacy/telescope-optics-calculator/
Support: [email protected]

For an astronomy-club demonstration while considering ScopeHelper, this telescope calculator offers a worksheet built from the dimensions you supply. Keep the result beside your equipment notes so an idealized number is not mistaken for a promised view of a particular celestial object.