I was going to put another thread after reading the dpreview article.
However I shall add it here.

Which would you choose? the 77mm Limited or the Sigma 85mm?

77mm
Advantages - It's a Limited so well built, fine optics, smaller than the sigma.
Disadvantages - no SDM (might be a plus or a minus depending on your point of view), optics are not optimised for Digital as its pre DSLR (but still stunning nevertheless), not as fast as the Sigma, More expensive (£110 more according to WEX - SRS has no price for the Sigma yet)

85mm
Advantages - Faster, has SDM (see above), Optics will be good as an EX model, popular focal length for portraits.
Disadvantages - No AF on film bodies, "it's a Sigma" stigma to other togs (yes there are people out there who put their nose up at sigma, i'm not one of them), cheaper than the Limited.

Personally, it would be a tough choice, but I would go for the Pentax, if only for its reputation as one of the finest Pentax optics ever, but I would understand why people would go for the Sigma.
If I had the money, I would have both.

Howard, to help (which I hope) you can have a comparison.

FA50 F1.4
Advantages - Light, small, can be used with film SLRs, cheaper, Pin sharp after F2.5
Disadvantages - No weather sealing, no hood (although you can get one for a fiver), no SDM.

DA*55mm F1.4.
Advantages - Weather sealing, SDM focus, hood, fast.
Disadvantages - Longer, (maybe) slower AF, can't be used on film SLR's(although some have said that theyt have been able to, you can't use on Mz-5n and MZ-3 which require an aperture ring), pricier, bigger, heavier.

The other two to consider are sigmas.

Sigma 50mm F1.4 EX DG HSM
Advantages - HSM focus, very good wide open, Able to be used on film SLRs
Disadvantages - Large, not as good stopped down as the Pentax duo, no AF on none SDM cameras.

Sigma 30mm F1.4 EX DC
Advantages - gives the EFOV 45mm in 35mm terms (but remember its still a 30mm), fast
Disadvantages - Not a Fifty, only Digital, no SDM/HSM, larger than the FA

All are good, but difficult choice. Personally, the FA50 is an excellent lens, and someone said the FA50 F1.7 is a tad sharper.

However, I would go for the FA50, not only for its size, but also its versatility.

I should add though, if you have not formatted external hard drives used on windows to NTFS and kept them to FAT32, you will be able to read and write to them on MAC with no problem. If you have, read only.

That I don't know, as I don't use MAC. However amoringello advises that it can read, but not write to NTFS.

I would say don't worry, as the file system that SDXC uses will be compatable with the two main operating systems.

The would explain it. However It won't be true 64bit, more of a hybrid to accept 32bit hardware and software.

Mind you Vista 64 and Windows 7 64 are not true 64bit anyway, only paired 32bit

Mac won't support NTFS, that I do know. NTFS was developed by Microsoft to support increased bit sizes of the new operating systems from NT onwards. FAT was an old file system that can be traced back to DOS.
However, as a consequence, external devices kept to FAT32 because of the differing file tables of MAC and Windows. Both could read FAT.
So, from mt previous message, I think that exFAT will be some sort of FAT hybrid that both OS's can read, yet cope with 64bit should external devices go that way.

The only thing so far with regard to SDXC is that it used exFAT file system (does that mean NTFS? I'm not sure. If it does MAC users won't be happy - it is possibly a hybrid) SD and SDHC used FAT32 not FAT64 as the majority of computers at the time were (and still are) using the FAT32 file system for external devices.
I think at the moment, that SDXC is still to be fully finalised even the SD 4.0 protocol that it demands (there is a hybrid SD 3.0 protocal too where you can get SDHC complaint devices to accept SDXC - but I think this will only apply to devices out within the last 12 months)
Although "officially" it has already been done.

Does the K-5 accept SDXC? I saw in that german markating blurb, no mention of SDXC, only SD and SDHC.

Finally, I am happy too about the ISO80 - great for landscapes and blurred water in bright light

Unfortunately it is the "big thing" at the moment.

It might be to do with slow zooms dominating the market these days, rather than fast primes of 15-20 years ago. Back then ISO800 and a prime of F1.8 was fine. However today, with "kit" and slow zooms of up to F6.7, people are not getting what they want and are demanding more.
It could also be a case of an "arms war" between the makes on who can produce the best.
Personally, I welcome it. I wont often be shooting more than ISO400, but I like the fact that if I need to occasionally shoot at high ISO's (to which I mean more than ISO1600) I can without thinking the images will be useless (mainly nature)

I had a feeling it might Mike.

Just to give a quick comparison of noise with the K-5 and K20D and K10D

here are some I took that you can compare with that image link for the K-5

K20D ISO1000



K20D ISO1600



K10D ISO1000



I know I can't replicate the K-5 image, but hopefully you can get an idea.