Pentax 645 1.4x and 2x Converters

[greg_lawhon]

I've seen conflicting information about the converters for the Pentax

645:

 

1. The 1.4x converter is sometimes described as "optimized" for the

300mm lens, but also usable with the 200mm lens. I think B&H shows it

as also being usable with the 120mm macro and one other lens as well.

Any comments on how it performs with different lenses?

 

2. Assuming clear information about the lenses it is usable with, can

you expect better resolution and contrast with the 1.4x than the 2x,

which generally is useable with all lenses? I've read that the Pentax

67's 1.4x converter is a better performer than the 2x simply because

it is optimized for use with certain lenses and not a "do-everything"

design. Of course, it might also just be easier to get better

performance out of the lower magnification. Any comments on the

differences in performance between the P645 versions?

[g._cheng1]

IMO opinion you will notice a slight loss of contrast when using the 1.4X on the P645 120mm Macro and the 200mm lens. I don't know about the 2X teleconverter, but I doubt if you're going to get BETTER image quality over the 1.4X. The 1.4X only mates with the 120mm, 200, 300 and 600 mm lenses because if you try anything else, the 1.4X flange may ram into the rear element of these other lenses.