# Finder Scope Just an extra visual aid you can use to find objects in the sky! With a central red dot feeding off a small, portable battery, finding deep-sky targets and planets has never been easier. Some telescopes actually have apps that rely on the finder scope. # Optical Filters - A Deep Dive ## Daytime Filters ### Eclipse Filters Cheap forms of solar filters typically come marketed as 'eclipse filters' - they're basically [[The Everyday Vault Backups/Physics/Waves/EM Waves/Polarisation (Waves)|polarising]] filters that block white light, so the sun appears like an orange sphere. Great if you're a sunspot fan! ### Calcium Filters A specialised filter meant for looking at the sun. Turns the sun blue or violet, given calcium has two spectral lines at 393.3 and 396.9 nm (Ca II for you nerds out there). Really, really nice breather to use every so often and is a great way to assemble a [collage similar to NASA's](https://svs.gsfc.nasa.gov/4117#:~:text=The%20movie%20opens%20with%20a,and%209.4nm%20(green).)! ## Nighttime Filters ### H$\alpha$ Filters ### O III Filters ### S II Filters