Astigmatism in Camera Lenses
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What is astigmatism?
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When you are photographing a subject that
has lines radiating from a common center, such as a spoked wheel, you
may infrequently notice that some lines focus more sharply than others,
and that refocusing at different levels through a scene may make lines
at a different angle appear sharper.
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Why is astigmatism happening?
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It is a result of unequal radial
curvature in the lens manufacture.
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How to overcome astigmatism?
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Image quality can be improved by closing
down the lens aperture.
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