So, I get mine shortly. But which lenses are compatible?

Now I know that the following are:-
smc PENTAX-DA 12-24mm F4 ED AL[IF]
smc PENTAX-DA★ 16-50mm F2.8 ED AL[IF] SDM
smc PENTAX-DA 17-70mm F4 AL[IF] SDM - 1*
HD PENTAX-DA 20-40mm F2.8-4 ED Limited DC WR
smc PENTAX-DA★ 50-135mm F2.8 ED[IF] SDM
smc PENTAX-DA 55-300mm F4-5.8 ED - 3*　
HD PENTAX-DA 55-300mm F4-5.8 ED WR - 3*
smc PENTAX-DA★ 60-250mm F4 ED[IF] SDM
smc PENTAX-DA 14mm F2.8 ED[IF]　
smc PENTAX-DA 35mm F2.4 AL
smc PENTAX-DA 35mm F2.8 Macro Limited
HD PENTAX-DA 35mm F2.8 Macro Limited
smc PENTAX-DA 40mm F2.8 Limited
HD PENTAX-DA 40mm F2.8 Limited
smc PENTAX-DA 50mm F1.8
smc PENTAX-DA★ 55mm F1.4 SDM - 2*
smc PENTAX-DA 70mm F2.4 Limited
HD PENTAX-DA 70mm F2.4 Limited
smc PENTAX-DA★ 200mm F2.8 ED[IF] SDM
smc PENTAX-DA★ 300mm F4 ED[IF] SDM
HD PENTAX-DA 560mm F5.6 ED AW - 3*
smc PENTAX-D FA MACRO 50mm F2.8
smc PENTAX-D FA MACRO 100mm F2.8 WR

But what about others? They say that the 21mm Limited is not as the rear optic would hit the converter. Thats fine. But what about non-pentax lenses? I know that the focal length in the camera will not register the change (no problem) but actually using it and avoiding hitting the optic on the converter.

I am thinking of the following
Sigma 105 Macro
Sigma 170-500
M42 Lenses
Pentax's own FA50mm F1.4
Sigma 24-70
Tamron 17-50 F2.8

It will be nice to know.

Mine is on its way, I should get it tomorrow from SRS. Looking forward to using it.

There seems to be in increase of Fisheye threads at the moment
Answer - 10-17mm I have had mine for 3 weeks and I love it.

I must be lucky to have the two most regarded DA* lenses.
As has been said several times on this thread, the 50-135 is probably the beast zoom Pentax has ever made, and possibly the finest Zoom out there (although I think some Nikon owners may differ and say their 14-24 is the best. But I digress). It really is a stack of primes all in one, and possibly the main reason why I have never bought a dedicated portrait prime such as the 77 limited. How often do I use it? Well how about just about everywhere. Studio? Check. Street? Check. Travel? Check. Monsoon weather? Check. Events, Theatre etc. You name it I have probably used it for that purpose.

The DA*300? All I can say, sharp from wide open and basically my replacement for the Sigma 170-500 for Nature etc. And it is several times better. Oh and I have even used it for event photography hand held. Perfect for the Job.

I will get a 60-250 at some point, as it will give me flexibility between the two. It won't replace the 50-135, as it is too big for studio work and portraits. but things like airshows it will be perfect.

I have also considered the 55mm, but having compared it to my K55 and Tak55, there is no difference in IQ. It's only advantages are AF and weather sealing.

I am going to look under the settee......

Interesting comparison, The clear loser for me is the Sigma, but that is probably due to the compromise of being a zoom in the first place.

Big surprise is the Carl Zeiss Jena. But then again having owned one of these lenses, I am not surprised. Shame the blades stuck on mine (it is now sat on a shelf). I have always loved this lens. Maybe I might get another, or blow some money and get it fixed. Hmmmm.

I have the Takumar bayonet, and the shots do show its abilities. But then again it is a lens that you have to work with. It all comes down to the light I have found. Warm contrasty light in an early evening it comes into its own, as it does with portraits in any light. But flatter light, or even bluer light, it can struggle.

I just wish that Pentax would bring out a DA*135 prime, in the range of F1.8-2.5 as it would be a big seller. In the meantime, I will enjoy my DA*50-135, TAK-K 2.5 and Cosinon 135 F2.8 M42.

All K-mount Samsung lenses are the same as Pentax K-mount lenses, same optics, same factory. The only differences are the rubber grip, the blue ring as opposed the green and the reflection has a blue tint instead of a green tint, not that this tint makes any difference whatsoever. Oh, and when new, the Samsung branded ones were cheaper.

I always thought the Sigma's own mount was actually based on the K-mount but with certain differences. Surely it would not be as difficult. I could be wrong in this aspect.

Having said that, Sigma do produce K-mount lenses with both screw-drive and HSM drive, so why don't they say for certain lenses, "We will make a K-mount version, but to special order only". That I would not mind a bit.

Ooh a challenge....
Looks like I will have to a comparison between my 70-210 and 55-300......

I know it is only a test shot, but shows the creamy bokeh of this very fine lens. Oh, and MattyH, your windows need cleaning.....LOL