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Photography

HAB911

(10,198 posts)

6. A catadioptric lens is a mirror just like the Hubble or James Webb

Reply to CaliforniaPeggy (Reply #3)

Sun Sep 7, 2025, 06:06 PM

Sep 2025

it fits 500mm of light travel in much less space. It's old technology, I bought mine in the '80s. It's old because it has many flaws, like reduced resolution and a hot spot in the center that sometimes is too obvious. Here is a photo of my 1000mm cat, the 500mm is much smaller. The Photoshop polar coordinate filter is one of many that can be applied to photographs. It basically transforms linear pixel selections into circular or oval shapes.