[mstratil]

I am new to Pentax cameras and would appreciate some help on a lens selection.

I recently purchased a 645D with used versions of the 45-85mm and 120mm Macro lenses. I'm pleased with both. Now I'd like something with much greater reach for doing wildlife.

A major contender seems to be the Sigma 150-500mm for Pentax FA. The major questions I have are:

(a) Am I correct in assuming the the "for Pentax FA" means that this lens will mount on a 645D?

(b) Has anyone tried this combination? How well does the lens auto-focus on the 645D? Is there vignetting? Any problems?

(c) Is there a better lens available? What about the Pentax 100-400mm FA? I can't seem to find any of these lenses, not even at the Pentax store. Has it been discontinued?

You can see that I feel a lot of confusion over these issues. Any help will be most appreciated.

Mike

[elho_cid]

No 150-500 is a 35mm lens. you need 645 format lens for your 645 format camera. Or other medium format lens with adapter (like lens for Pentax 6x7 system).

Look here what are the options available:
https://www.pentaxforums.com/lensreviews/category-SMC-Pentax-645-Telephoto-Primes.html

[dmc]

No. You need a lens for the 645.

[blackcloudbrew]

Sadly while one can go from a 645 lens to a 35mm mount lens via converter, you can't go the other way (that I know of).

[mstratil]

My understanding is that the SMC 300mm f4 ed if will work fine on the 645D.

Is that correct?

Has anyone had any experience with this combination?

[elho_cid]

Yes, but only A* 645 or FA* 645. Not the DA*. Only lenses marked as 645 can cover the large image sensor.

[mstratil]

OK. What about this:

SMC Pentax-FA 645 Zoom 150-300mm F/5.6 ED IF 645N 645D

What limitation does the lack of the star entail?

Mike

[elho_cid]

Pentax marks the top of the line lenses with stars. Lack of star generally means, that you can buy a better lens than this one. But it doesn't imply the starless lenses are bad. Many are still great.

[mstratil]

Thanks again. Maybe it would help a lot if someone could explain the other major designations:

FA

F

SMC

ED

IF


Mike

[CDW]

The FA 645 150-300 is actually considered an extremely fine lens and it is very hard to find, and still remains pricey on the used market. Typically around $2,000.00 used. If you can find one at a good price, grab it.

[boriscleto]

Thanks again. Maybe it would help a lot if someone could explain the other major designations:

FA

F

SMC

ED

IF


Mike

F series lenses were the first Pentax AF series. FA replaced the F series. There was no F series in 645.

SMC = Super Multi Coated, first introduced in 1971. The SMC series 35mm lenses in K-mount are also known as the K series.

ED = Extra low dispersion

IF = Internal Focus, meaning max focal length is only at infinity focus.

[Pål Jensen]

Pentax marks the top of the line lenses with stars. Lack of star generally means, that you can buy a better lens than this one. But it doesn't imply the starless lenses are bad. Many are still great.

Actually it doesn't. Pentax don't use much stars for their MF lenses. The FA 35 and the 120 Macro both lack the star designation but both are considered the best wide angle and telephoto lenses ever made for MF.
Petax seem to use the star designation when a certain number of exotic glass elements goes into the lenses.

[Pål Jensen]

OK. What about this:

SMC Pentax-FA 645 Zoom 150-300mm F/5.6 ED IF 645N 645D

What limitation does the lack of the star entail?

Mike

I have only used it for film but it is an astonishingly sharp and high resolving lens. I cannot distinguish images shot with this one or the FA 120/4 macro.

[tuco]

Interesting. Was $10,000 bucks a spontaneous purchase?

[oldframe]

Reminds me of a compatriot who could not imagine living on a budget of less than 2,000€ a day.
Ah well, perhaps, like the Duke of Edinburgh once feared, I should give up polo