The direct camera output maybe. I regularly use ISO1600 and even ISO3200.
When I used to use JPG, I used NeatImage to clean up the noise (I even provided the *ist-D profiles to NeatImage).
Now I use RAW and Capture One LE, the results are, quite frankly, amazing. I've used other RAW convertors, and these produce good results, but I've always had to run them through NeatImage too. C1LE has some great noise reduction built in (and automatic hotspot removal too).

So, I'd say, shoot RAW. If you don't have a convertor, use RAWShooter Essentials from www.pixmantec.com - if you upgrade to something else, you always have the RAW file to work from.

Additionally, shooting RAW will give you another one or two stops of margin (because it is 12-bits per pixel, not 8-bits) which allows you to correct on the PC, even if the original image is underexposed

Matt

Physically it's fine. As John said you get some vignetting. However, I've used it at 16mm on an MZ10 and I didn't mind the amount
I've provided a link with the first tests I did: http://www.pbase.com/mattmatic/smc_da_test

Matt

There's a thread about the subject: http://www.ephotozine.com/forum/viewanswers.cfm?qid=23959

There's some safety tips and shooting tips here as well: http://www.mindspring.com/~josephmatthews/how_to/safety.html

Hope that helps!
Matt

Thread is here: https://www.pentaxuser.com/forum/viewtopic.php?t=266
(on remote shutter release)
Matt

Sounds like an electrical problem (or electronics within the 2x itself).
The Z1 & Z1p don't have the mechanical finger to read aperture, so they read the lens information digitally.
Most of the contacts are used to indicate max & min apertures, and there's an extra connector that is for digital transfer of information. I would double check the contacts on either side of the 2x.

Does the Sigma works fine without the 2x on the Z1?

(Sigma apparently refuse to pay the royalty for the body-to-lens communication protocols, and choose to reverse engineer it. Seems they don't always get it right, especially when dealing with the nuances of older bodies )

Matt

John, that kind of policy is fine so long as it's not for professional equipment
Matt

Looked on www.ephotozineshop.com and the Flashtrax/Phototainer is really quite cheap in 20Gb (£169).
Look under "Hard Disks" and "Smartdisk". There's also the "Photochute" which connects directly to the camera via USB, pulls the files off and stores on a 20Gb drive. Tiny size (it looks), and £139.
Might be worth investigating further
Matt

John, does the Epson handle the RAW format or is it just JPG sRGB?
Not the amount I shoot in RAW, John
Matt

Not many of the hard disk units can read RAW formats, and fewer still read Pentax RAW.

The Innoplus FlashTrax/Phototainer does (and, although a little outdated, this is what I use. Been a lifesaver). For SD cards you'd need an SD-CF adaptor (because the FlashTrax has a Compact Flash interface). The LCD is not the sharpest in the bunch, but it's not let me down yet.

And although I've been looking for smaller devices with better screens, I haven't yet found one that reads Pentax RAW (which is all I shoot)...

Matt

My mistake - just looked on Google. It is "parfocal", not "parafocal". DOH!

But the point about the *ist-D (and probably the *ist-DS) is valid - my Tokina was parfocal on the Z1, but not on the *ist-D. It's not the lens, but where the camera focuses.

Matt