hi ray -
i am not sure if the lens i have is the same one - but i have a wollensak 13-20-25 triple convertible lens. it is mounted in a betax#5 shutter and it can trip inbetween the marked shutter speeds. i have read that some people have had trouble with the lens not being sharp unless both elements are being used but i have not had any sharpness issues in all the various configurations the lens offers. i don 't enlarge 8x10, but do contact prints with paper and film so maybe sharpness hasn't really become an issue with me, i don't know. it has a large image circle and covers a 8x10 negative with ease.
-john