TELECONVERTER? Which, When, Where, and Why?

[LaRee]

Interesting combination that I never thought of!  I would try that on the weekend!

So, did you have a chance to try it out? I like the combination a lot for insect work. It really works a treat.

[Ben_Tax]

In terms of tcs: I have collected app. 10 of those. The very best I ever encountered is the Pentax 1.4x-L - but due to the protruding lens element, it fits only certain lenses. I use it mainly with the old Tamron 60B 300/2.8, which makes for a still fast 420/4.

Second to that is the Pentax 1.4x-S, which fits basically any lens and is still extraordinarily good. Especially on the Sigma 70-200/2.8, the Sigma Apo tc 1.4x really shines. The image quality loss is minimal and focus is still fast enough for real world photography.

From all the 2x tcs, I find I only use the Pentax 2x-L, which is not quite as good as its 1.4x-L brother, but still above the other 2x tcs I knwo off. The Pentax 2x-S is nearly as good, but only nearly. The Sigma Apo 2x tc disappoints a bit - at least my copy. I have seen amazingly good results from other photographers, but my copy is not as good. My only other AF tc is a Kenko 1.5x, which also works with SDM and is very good, though really nothing to compare to the Pentax tcs. Apart of course from the old Pentax K6-T 2x tc, which seems to perform okay with older lenses, especially the old K 300/4, but otherwise is really nothing to get ecited about. The Kenko MC7 2x tc is markedly better.

Something forgotten? Oh, yes I also got a Pentax AF adapter 1.7x, but hardly ever use it. I made some test shots with the old Pentax 500/4.5 (my version is one of the latest) and the AF adapter certainly works nicely in AF-terms, but the increase in CAs and purple fringing is excessive, even when the lens is stepped down to f/8. With other lenses I really never seriously used that thing, though it should make a good combo with the Tamron 60B.

Ben

[natasredrum]

I haven't tryed any Pentax AF tele's since they are so hard to come by, but the Tamron -F Pz-AF MC4 1.4X Is a awesome one for sure, also works in SDM. And for a $125.00 it's not a bad price.

[wtlwdwgn]

I have the Sigma 1.4X and Pentax F 1.7X. I've used the Sigma more with the Sigma 100-300 f/4 and have had pretty good results. I haven't had the F 1.7X very long and the few images taken with it show it to be pretty sharp but slow on a 300 f/4 lens (f/6.7) so it doesn't AF well. I've looked for a Tamron -F Pz-AF MC4 1.4X but they are as scarce as hen's teeth.

[Ferry_Cung]

is there teleconverter for DA*50-135mm f/2.8 

[rei_vilo]

Pentax used to announce rear converter SDM, before the merger with/acquisition by Hoya.

The converter was announced on the lens roadmap of September 2008 and later removed 

Any fresh news from Pentax about the DA 1.4x rear converter SDM ?

[blackcloudbrew]

I have a Kenko 1.5x t/c for pentax. It works ok and works with SDM. But it definitely has some issues hunting for focus below f4 just as its manual suggests. Works fine with my DA 55-300.

Tim