well, i know about the greater than and less than 300mm specification for the L and S extenders. i focused the entire range on the 400 f5.6 by hand without a camera attached to see the range of travel. it looks like i can focus to about 15 feet or so before the rear element would hit the L converter. in MF mode, the focus clutch slips as soon as it encounters resistance. the lens end of the L converter is covered with rubber where the retaining ring/cylinder holding the rear element of the lens would contact. from what i can see, i would not damage anything in MF mode hitting the rear element cylinder against the rubber ring, but it would be inelegant. i have to use an S converter on my FA* 80-200 f2.8 because the rear element is fixed and right up against the lens mount.
Herb... ----- Original Message ----- From: "Kenneth Waller" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, March 26, 2004 7:56 PM Subject: Re: tele extenders > Herb, before I purchased the S convertor for my 300mm f4.5 FA, I spent some > time with Pentax Colorado trying to determine the recommended usage. There > was confusing literature out there and it took them a while to come up with > the correct application info. IIR, it went something like the S is to be > used on lenses shorter than 300mm except for the 300mm f 4.5, in other words > not on the 300 f2.8 and 400, 500 & 600 mm lenses. > Physically, I believe you could cause damage to the lens by trying to fit > the L onto lenses where the S was recommended. The L has a significantly > longer "snout" and would contact lens elements on those lenses.
