Here is what I have from a Pentax Lense brochure (unknown date, but after FA lenses were introduced and A lenses discontinued). There is a table with all lenses and 4 columns, one for each teleconverter. There are 3 marks in the columns...
X - not usable for this lense, this covers most lenses with the 1.4x-L and 2x-L . O* - Better performance can be achieved. This symbol is under the 1.4x-L and 2x-L columns only and next to 4 lenses, A*-300/2.8, A*-400/2.8, F*-600/4, and A*-600/5.6. I take this to mean that these, and only these 4 lenses will benefit from the "L" converters. O - Usable, this covers 11 other lenses, in whole or in part. Both are usable with... A-500/4.5, FA*-600/4, P-1000/8, P-1000/11, A*-1200/8, F and FA*-250-600/5.6, A-200/4 Macro, and A-Soft85/2.2 ...and only the 2x-L usable with A-400/5.6, F-135-600/6.7 ...and only the 1.4x-L usable with the P-400-600/8-12 Regards, Bob S. I wrote:: I have the A1.4-S Teleconverter and it works fine with the A300/4 lens. The L teleconverters (A1.4-L and A2.0-L) are for very special applications, big fast glass. They have long snouts that won't fit in the A300/4. The L's are designed for the A300/2.8, A400/2.8, and such. I have the specs in some old Pentax literature at home. Go look at them on Boz's site. Regards, Bob S. Sas Gabor writes: > Don Herring wrote: > > I am planning to get a 1.4-S teleconvertor, > > mainly to use with my A* 300/4. > > > > Can this particular converter be used with a > > 500/4.5 screw mount (with the > > screw mount adapter of course)? > > It can be used of course, but for these focal lengths the > 1.4-L converter is definitely a better choice.
