Watch the video: What is focal length? Take two 50mm lenses: an f/1.8 and an f/1.2. Even though they both have the same 50mm focal length, they're not the same physical length – and neither of them is ...
On the first night out with my brand-new Celestron NexStar 8SE back in July 2015, I knew little about the relative sizes of astronomical objects. I was bowled over by my first view of Saturn — an ...
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