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Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1833541" data-attributes="member: 68323">The Zeiss FL have a rather flat field (that is apparently a design attribute of the bin) but they have more astigmatism at the field stop. This was true of the previous Victory too. So adding a field flattener would not directly improve them though it would loosen up the need to increase the astigmatism as the edge.It's important to distinguish between a field curvature and astigmatism in the field edge. Not the same thing. Same with pincushion distortion (which is independent of the other two properties).</blockquote>