Originally posted by Pitagora Is there any way I can evade moire in photos without affect the picture clarity and sharpness?
Yes, and that is to get a camera that doesn't have a Bayer-style sensor. In practical terms that would mean buying a camera made by either Sigma or Fuji.
Nevertheless, since we're talking about your very first DSLR, I would suggest that you forget about all the fancy details in the spec sheets, be it Pentax or any other brand, because none of it really matters before you have some actual shooting mileage under your belt.
I'd say forget about the faster than light autofocus speeds, astronomical ISO's etc. at this point. Save your money and go for a nice regular K5 along with a nice lens or two, even a used one at first, and then practise, practise, practise with it. When you've got some first hand experience and enough shooting mileage under your belt, you'll know much better what you really want and what you really need. Then it'll also be easier to tell the difference between the want and the need.
We've all been newbies at some point. It's often not the most practical idea to spend a lot of money on the fanciest and priciest top of the line model as the first ever DSLR. Even though that's how many people do start. But the fact is that, when you're just starting DSLR shooting, both your experience and your taste on camera gear will change. After a while you may even end up wanting a different brand camera altogether.
Worst case scenario; One day you might even find yourself lusting after... gasp, a Canon! Horror!
So again, I'd suggest that you go for a nice but not too pricey body, and save money for at least one decent lens, too. Your taste and needs for the camera body may change in time, but good lenses will always be good lenses.
Forget about the fastest multi-point AF, highest ISO, fanciest anti-shake and other spec sheet erotica at this point, and concentrate on finding a DSLR body that feels nice in your hand, has a nice, uncluttered user interface, all the manual modes easily obtainable, and minimal amount of auto-everything modes. A used K5 would be a nice option indeed. Or even a K-30. Both will work just fine for landscapes and portraits.
Then, when you do get one, ignore all auto-everything crap, and learn how to shoot in plain old M mode, as well as in aperture and shutter priority, too. Don't forget to at least try manual focusing once in a while, too. It's there for a reason. Even put the ISO setting to manual, don't let the camera set it for you. That way you'll learn and become a better (D)SLR photographer sooner, and you'll know what actually makes a good photo.
(hint: it's not the fancy spec sheets
)