[Ben_Edict]

Interesting, except for the length of the extension, which is more than the sigma APO 1.4x and 2x TCs, the diameter is the same, 3.5co, That means it would also probably work on my sigma 70-200F2.8 and other sigma lenses intended for sigma TCs. Optically, who knows?

It won't fit, I just tried. The rear element of the 70-200/2.8 is not far enough recessed to accomodate the Pentax L-convertors. It would probably work on the Bigma, if you use focal lengthes above 200mm or 300mm (I did not measure exactly).

Ben

[Ben_Edict]

would this TC work with k400 f5.6? what is the diameter of the part that sticks out into the lens?
Thanx

To my knowledge, the A 400/5.6 is the only 400/5.6 Pentax lens, that is compatible with the L-convertors. At least the M version will definitely not work.

Ben

[axl]

To my knowledge, the A 400/5.6 is the only 400/5.6 Pentax lens, that is compatible with the L-convertors. At least the M version will definitely not work.

Ben

why the M400 doesn't work? won't it accomodate the extending element?

[Ben_Edict]

why the M400 doesn't work? won't it accomodate the extending element?

exactly. The A 400 seems to have a farther recessed rear element.

Ben

[Marc Langille]

Front element is ~ 3.5cm in diameter, and sticks out ~ 2cm.

I sent this information to Adam, and he thought it was good information to have. It's now in the 1.4X-L TC description in the Lens Review DB.

Cheers,
Marc

[Canada_Rockies]

so i'm guessing it works with the f*300mm?

Nope, won't work. I thought I could fit it to my 400/5.6 M, but the barrel is too narrow! The rear element is way up there, so I thought.... Basically, if it is not on the list posted above, it won't go on.