🔭 BuildToDoGood Astronomy

Astronomy tools and honest reviews. For the backyard observer who knows the eyepieces that came with the scope are mediocre and wants to upgrade without spending $400 on the wrong one.

The amateur astronomy internet is mostly two things. Beginner Cloudy Nights threads (excellent, but archived from 2009 and hard to search). Or YouTube reviewers in light-polluted suburbs claiming their telescope shows nebulae that you can't see from a Bortle 5 sky. Neither one is the practical math you need for tonight.

These tools are for tonight. The magnification calc that tells you what eyepiece pairs with what scope and at what field of view. The Bortle-scale honest expectation guide for your zip code. The transit-time predictor for the planets above your horizon right now.

Tools

Telescope Magnification & FOV Calculator Magnification, true field of view, exit pupil, and theoretical max useful magnification. By scope focal length, eyepiece focal length, Barlow factor, and apparent FOV. Bortle-Scale Expectation Guide soon What you can actually see from your sky class. Honest about Magnitude 7 globular clusters from Bortle 6 (you can't). Eyepiece Pairing Recommender soon Given your scope, what eyepiece focal lengths produce useful magnifications for different targets (planets vs deep-sky vs wide-field). Conjunction & Transit Finder soon Planetary conjunctions, lunar transits of bright stars, ISS passes. By location and date range.
Plain note about money: Some product links are affiliate (eBay Partner Network). Small commission on purchases. Doesn't change your price. The eyepiece recommendations come from real eyepiece comparisons through real scopes under real skies. If the cheap option matches the expensive one at your light pollution level, I'll say so.