Oh, and I also use the 50mm summilux as my standard lens, though I hadn't thought of using this with an extender at all. I shoot mainly landscape and interior details, at zoos and aquariums. from all of the helpful comments, I may invest in the 100mm apo. Sincere thanks, James -----Original Message----- From: jkfdesign@xxxxxxx To: leicareflex@xxxxxxxxxxxxx Sent: Wed, Dec 2, 2009 1:29 pm Subject: Leitax and apo extender First, I have been following this list for nearly six months now, and am truly grateful for the amazing images that you show. I have been a little too timid to post my own, but might do so soon (for camaraderie and what I am sure would be helpful critique!) I do have a question regarding the Leitax conversion (for me, it would be on a Pentax as I still maintain my first camera, a K1000). I am shooting with an R5 now, using mainly the 80mm Summilux, and the 135mm. While the Leitax site claims that the apo-extender would not degrade performance, is it an option to use the apo-extender with the summilux? I would like to keep using the R5 as it has become so natural feeling in my hands...and this seemed like such a good idea... best, James James Karl Fischer james@xxxxxxxxxxxxxxx