Pentax 645 FA 300mm f4

I'm thinking of buying a Pentax 645 FA 300mm f4 in the near future. My 45mm
and 80-160 have given me excellent results.
How do you like this lens...is it difficult to handhold at 125th without
getting motion blur (for someone with excellent technique).

Is the 5.6 much different other than aperature?

Thanks-

I had the manual focus version of this lens and it was pretty swell. The 5.6 AF model is probably smaller. Hand holding the manual version was not easy, as it is a very heavy lens. I imagine that hand holding the AF version will depend on the size and arm strength of the user.


Pentax makes an amazing 600mm 5.6 for the 645, and it can be had for a song if you can find it.