Originally posted by kaseki I was quite surprised that the combo of teleconverters would even work. I first tried it a couple of evenings ago when taking pictures of the moon. With its bright light the small effective aperture was not too much of a problem. The only weird part is that the camera reports an f stop of f8 when the lens is open full at f4, which is not possible of course. Probably the result mixed data reported to the camera and the engineers never dreamt that someone might actually hook up a combo like this.
Here are a couple of shots of the moon with the full enchilada (P67 400mm + P67 TC1.4 + P67 TC2.0 + P645 TC 1.4) = 1568mm @ full open aperture => f/16. The first is the uncropped version with minimal processing in ACR. The second is a cropped version to about 80%. I'll post some pics and my conclusions of the setup in the Behind the Scenes thread.