User talk:132.230.195.81

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Happy editing! --Srleffler (talk) 17:29, 13 March 2020 (UTC)

Petzval field curvature
Re:your edits to Petzval field curvature: Whether the sign should be positive or negative depends on the sign convention that has been chosen. If you want to change it, you'll need to explain why in more detail than just asserting that "its radius is negative".--Srleffler (talk) 17:29, 13 March 2020 (UTC)