Pentax 250-600 mm lens

Hi,

I�ve just got myself a second hand Pentax 300 f 2.8 (manual focus)

lens + two Pentax TC�s ( the 1.4X and 2.0X �L� series) that I�ve used

in Namibia. I�m very satisfied with the 300mm lens (but less with the

combination 300 + TC�s). I�m interested in taking pictures from a car

(in National parks like the Kruger N.P) so weight isn�t a big issue.

I was planning to sell the two TC�s in the future and add a second

hand 600mm from Pentax (f/5.6 or f/4, depending on what I find and on

costs).

A local store is selling a second hand Pentax 250-600mm f/5.6 manual

focus (with visible scratches on the outside) for about 3.500 USD, so

I would like to know if anybody knows how this zoom compares, as far

as optical quality is concerned, to the 600mm, and eventually would

it be worthwhile loosing something in quality but gaining the

versatility of the zoom lens. Thanks for now.

I've never heard about a Pentax manual focus 250-600mm lens. There are two Pentax 250-600/5.6 lenses; both auto focus. Theres the F version that comes in a white casing and the current FA silver colored version that also has power zoom. I don't know if there are some optical differences between them.

The FA lens is supposed to be totally fantastic. I think Phil Greenspun once mentioned somwhere on photo.net that he had a friend, a Nikon or canon user, using and swearing by it. Reports on the Pentax mailing lists says this lens is awesome.

I've yet to hear from anybody who has compared the FA* 250-600/5.6 ED IF with the FA* 600/4 ED IF but theres a review of the FA* 600mm here on this forum under the title "Pentax big glass" (or something like that).

Philip's friend's exhibit shot with the 250-600 can be found <a href="http://www.photo.net/photo/rsabin/index.html">here</a>.

Considering that the F 250-600/5.6 has 17 elements and 15 groups, and the FA 250-600/5.6 has 18 elements in 16 groups, I'd say they have a different optical formula. Since both lenses are currently available new, with "only" a $500 price difference (at $7100-7600, $500 isn't so much), I'm sure one could call Pentax USA and get information on the differences in performance. If Pentax re-designed the optical formula, there must have been something they wanted to improve, but whether the later FA lens is necessarily better is unclear. Sounds like it is possible they added one extra element to the design to better correct for something, but it could have been a complete re-design.

I just wanted to thank all of you for your contributes, just for the information the lens is the "F" version (the white one and is AF).

I don't really like zooms, but the shopkeeper told me to give it a try, and I guess that that's what I'll do (it's still there after two months).

Thanks again to all of you.

Pier Paolo