Reducers & Barlow Lenses: How to Change Focal Length Without Changing Focal Length

NASA defines focal length as the distance light travels from the center of aperture to where it comes into focus, a fixed and physical property. But reducers cut back focal length and make images brighter while Barlow lenses increase focal length and make images dimmer, yet they don't make telescopes longer nor give them more aperture. What dark magic is this! To watch: What Happens to Light When It Comes Into Focus:    • What Happens to Light When It Comes Into F...   To watch: Understanding Focal Length: Trading Speed for Detail:    • Understanding Focal Length: Trading Speed ...   To see high res versions of the images used in this video, check out the Sky Story Astrobin: https://www.astrobin.com/users/SkyStory/ *** *** *** We are Telescope Canada's first affiliate. It's a great place for astrophotography gear with fast service and an informed staff who are passionate about astrophotography. Using the following link adds nothing to your cost but helps us produce more educational videos about this amazing universe around us. Just copy and paste the link into your browser: https://telescopescanada.ca?bg_ref=KK... All videos best viewed in 4K. Peer into the cosmos on Sky Story and along the way come to appreciate our world all the more. Here, we explore the realm of nature beyond our Earth through the fields of astronomy and astrophotography. All our programs are committed to the standards of scientifically accurate, high quality content that aims to educate and inspire. New videos are posted almost weekly, so please subscribe. #astronomy #astrophotography #space #nebula #stars