comparisons

Here are two lenses with curious specifications: a 20-50mm and a 20-40.  One is a lot smaller, one is rather faster at f/2.8-4.  Both are optimized for APSc sensors,  both are computer-optimized to do their best given the other constraints noted above.  Both do the job rather better than others from their respective companies.  Neither is stabilized internally nor is geared to closeup work.  One cost me $60 used, the other $680 new but open-box.  Interesting!

Yes, the tiny slow one is Samsung's 20-50mm f/3.5-5.6 II.  It has no OIS because it's designed to be small.  It does have the iFunction button on the side, press it and turn the front dial to control settings like white balance, shutter or aperture or ISO, and such.  The Limited from Pentax is solid, weather sealed and built to their Limited standards so metal and smooth focus are pretty much forced upon it.  It also has a DC motor inside for silent focus.  Both lenses appear to test out quite well and in online tests I've seen both leave their 18-55mm siblings far behind.

Note that the Samsung unlocks to become similar in length to the Pentax Limited zoom on the right, but this is what you carry with you between shots - so it matters.

I do not have the NX300 yet so no test images from the 20-50 for a few more days.  And by the way, camerasize.com shows us the camera-body difference as well.  Same sensor size, and similar sensor quality as measured at DxO labs. The Pentax (Sony sensor) outpoints the Samsung by a bit, but not by much - and the latter adds 20% more pixels to the equation.

http://camerasize.com/compare/#373,394

No doubt the Pentax has more external controls and it's a familiar feel to me.  It has two control dials and numerous external buttons & switches that I would miss.  It has a viewfinder, and while I have managed my Q and a K-01 without major problems I would miss it.  The NX300 has a tilt screen and I have missed that for some time!  Samsung also has WiFi , video-autofocus and the ability to adapt most older Pentax lenses to work manually.  And a larger screen.  Nice.

So how do they compare in my budget?  Glad you asked.  One is a lot smaller, one is 'full-featured'.  Both are optimized for APSc sensors, and scores are similar.  Both are computer-optimized to do their best given other constraints, and both do the job rather better than others from their respective companies.  One is stabilized internally, the other uses stabilized lenses.  One gets 800+ shots per battery charge, the other closer to 400; not surprisingly the factory-original batteries differ in retail price by a similar amount.  Curious though - K.Tuck reports that he had Pentax-like battery life when he tried the NX300...

One cost $650 used, the other $250 used/open box. So camera plus lens = $1330 or $310. 

Interesting, again.