Hi,
I'm looking for the equivalent f-stop for front and rear 'only' configurations... I have a Velostigmat Series 1, 12.5 inch that converts to a 20" (508mm-rear) and 28" (711mm-front). Is it the same as other convertible lenses, double the aperture number for the effective f-hole? (example 6.3=12.6) ?
... or any experienced users of triple convertibles, do you know something about this lens?
thanks
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