With 400mm 1:9 (200 * 2x coverter) you will see almost nothing in viewfinder and also will not be able to take photos without having whole thing on heavy tripod and without your breath at hold (not because excitement, but due to shake from air moving over the camera)
I must have ninja camera handling skill and bionic vision then, because even at max zoom with the 2x teleconverter hand-held stability isn't an issue and the image in the view finder is perfectly clear and bright as daylight.
I've just unboxed my new Pentax camera and have had a quick play after putting 20 minutes of charge into the lithium battery. Crappy overcast weather outside right now, but good enough to confirm that the Pentax DSLR works perfectly fine with the 200m lens alone. However when the x2 teleconverter is put in-line, even so the image is perfectly clear in the both the viewfinder and on the LCD ("live view" electronic viewfinder mode), when a frame is snapped the resultant image is all white and blurry. Don't currently know if there is a setting work-around to get the teleconverter operating correctly; I've got a thick manual an a million settings and options to familiarize myself with.
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I ended up getting the K-50 body from ebay-store seller/photography wholesaler "DCxpert"; $499 and free postage. Yes the $100 more expensive KS1 is pimped a bit. In addition to the 4M-pixel resolution advantage the KS1 also has a GPS for "geotagging" photos and it is capable of continuously auto focusing in video capture mode. Specified battery life for the KS1 is actually little better than for the K50, besides all those funky LEDs and control illumination. Besides all that though it's pretty much a draw from a technical standpoint. I don't care for the pimped styling of the KS1 however and the K50, which is about 10% physically larger, is heavily ruggedised and dust/splash proofed, which is what sold me in the end (considering where I'll be taking this camera).
@35mm (min.) Hydhl Sicor lens, Hoya UV(O) filter:
@200mm (max.) Hydhl Sicor lens, Hoya UV(O) filter
As above but at @400mm with x2 teleconverter in-line