Thread: Review: Orion Sky View Pro 100mm ED EQ Telescope
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Old 18-03-2006, 12:35 PM
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Starkler (Geoff)
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Paul the 100mm has to have a longer f ratio than the 80ed to maintain colour correction. To make it shorter would make it more of an achromat.

The focal ratio required to be colour free is a function of the aperture.
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