Back-Focus 101: The Petzval Lens ft. William Optics RedCat51

In this episode of back-focus 101, I show how to obtain proper back-focus on the Petzval, using the William Optics RedCat51 as an example. This is probably the easiest system to obtain proper back-focus, as you will see in the video. Are you interested in knowing how filters affect your back-focus? Please consider making your astronomy purchases from my AgenaAstro affiliate link below. This helps me fund the channel, and allows me to produce my tutorials and unbiased reviews that you can trust. My link: