@stevebrot: I tend to exaggerate, but more or less, yes (Lauren disagrees with me, and I can understand her reasoning, but she is using her cameras under specific and controlled circumstances, and wants to use _one_ oddball feature the others don't have). There's weather sealing, but competitors offer that too, though to a lesser degree (and the question is if, with the problems the camera has, it would ever be used in a way where the weather sealing comes in handy). There is no stabilization whatsoever that could be used. Sony uses a similar system, but much better implemented. It does not show rolling shutter effects. Canon, Nikon and Panasonic have stabilization with stabilized lenses. Olympus has a great in camera system. Other brands take better video (for example by having a better encoder or a clean HDMI output). Other brands/models have a more usable video AF or are as bad, but offer other advantages.
A camera that offers pretty much what the K-3 has to offer, but with better video quality, and with a tiltable screen, is the Nikon D3200. Which costs a fraction of the K-3 (yes, no weather sealing... but I'd argue that the K-3 is mostly at home in very controlled environments, with little movement and detail in the background/foreground. Doesn't sound like a wet place to me...). Or, if you're willing to go for Magic Lantern, any Canon will be great. The 70D even offers GOOD video AF!
Originally posted by patarok AFAIK the K-3 has AF in Video Mode... (That feature that was asked for in first place?) And what do you actually mean by no stabilization? Why should it be bad ad details? It has a "selectable" low pass filter, so in video mode there is no low pass filter, what should make it more detail-rich then any predecessor...
explain the technical details... i want to understand that...
Ok, in comparison to the Sony a57 that was eventually bought you need to press a button to AF. Then it will noisily hunt back and forth for a couple of seconds until it hits the focus. Then it stops. This of course looks and sounds very irritating. In contrast the Sony has continuous AF using the phase detect sensors used for stills too instead of contrast detection, so it exactly knows what has to be in focus. It doesn't have enough focus points, so it may not always chose the spot you'll want, but it's miles ahead of Pentax. The K-3 AF is good enough to be on the spec sheet, but in real life you'd probably only want to use it in moments where you'd cut... it saves you a few seconds by not having to stop recording, focus, and start recording again. In contrast, apart from being too fast/not smooth enough, the Sony AF is quite close to a camcorder. Canon has good video AF in the 70D (thousands of phase detect sensors on most of the sensor), Panasonic and Olympus are decent too. Some cameras also offer focus peaking, which assists greatly to get the right focus. It exists on the K-3... but doesn't work during video recording, only before that.
I've mentioned stabilization before... Sony has the worst stabilization apart from Pentax, cause it's electronic too, but at least it only introduces one sort of artefacts that is irritating... the Pentax adds another one on top that is even worse. A picture that blurs occasionally in different direction (motion blur) despite being stable (Sony has that too), and then additionally wobbles around even though the picture (at least the top part of it) is stable. Canon and Nikon charge extra for stabilization, and you can't use any lens, but the option is there should you need it. The K-5 had a better system that also worked all the time (and the hardware is in the K-3... it's just they didn't activate it in the firmware!). Even better is what Olympus has... same system, but even better implementation. It is outright ridiculous. Pentax could fix it easily, by adding an option in the menu asking customers which stabilizer they want to use, if any. Btw. what the K-3 uses also leads to a crop of the frame, you'll probably get something like a 1.8-1.9x crop rather than 1.5x. Might as well shoot mFT... at least they've got the wide angle lenses to counter that!
It is bad at details because of the encoder. The K-5 had MJPEG... not exactly advanced, but with the bitrates offered it actually works really well. You'll run through memory cards really fast, but the quality is there. Details are preserved, grain is preserved, movements do not trouble it at all. The K-3 uses h264, which is a vastly superior codec, but needs a ton of processing power (for example to be really efficient and good quality I've set my encoder to some rather high settings on my computer. It results in 0.6-1 fps. On a quadcore Intel i5 with 4.5 GHz. There aren't 30 quadcore Intel i5 inside the K-3). The encoder in the K-3 is a particularly... meh variant, with some bugs (though later firmware versions may have fixed that, it seems?). Movements it doesn't like. Details it doesn't like either. It will lead to blocking at the quality settings and maximum bitrates they have set fixed in the camera... which aren't particularly high. Sony, Panasonic etc. IIRC can go right up to 50, 100, 200 Mbps. Pentax is limiting to 25 Mbps... And keep in mind that Sony and Panasonic use superior encoders, that even at 25 Mbps should easily beat Pentax at 25 Mbps. The K-3 probably has the capability to shoot MJPEG with 80 Mbps, it's just not activated.
Nikon, Panasonic and Sony (and I guess Canon with hacked firmware?) also have a clean HDMI output, thus giving you the option of plugging in an external recorder that can for example save barely compressed video with a ton of detail.
Having no low pass filter seems like a bad idea to me too. For some DSLRs you can install an additional filter to make the picture even blurrier, so that you don't get as much aliasing and moire. IIRC some people even intentionally focused wrong to avoid moire and aliasing. No low pass filter is only ok when you read all pixels on the sensor, rather than just a few (as Pentax does). That would also lead to better dynamic range, better low light capabilities etc. On the other hand this would heat up the sensor more, lead to more rolling shutter effects (good stabilization actually can help pretty much removing all rolling shutter that is really distracting... skewed lines in fast pans are nowhere near as irritating as wobbling back and forth due to small shaking/jitter (which the stabilizer would eliminate). You'd also need a fast CPU to downscale the 24 MP image (with crop thanks to 16:9 maybe 16-20 MP ish?) to 2 MP. Sony and Panasonic do pixel binning in their more video focused cameras, and I'm not sure about the 5D Mk III.
And I didn't even mention that Panasonic and Sony can do 4K video.
To me the disadvantages of a Pentax for video can be ironed out by having that great stabilizer and MJPEG codec... it gives the camera enough advantages to consider it. Heck, I'd consider Olympus, despite poor low light capabilities (relatively), poor dynamic range (relatively), only ONE frame rate (and one I don't like!), just because the stabilization is so good and would be worth it for me. The K-3 offers no such advantage though, even though they could add it in the firmware. MJPEG video is supported for time lapse videos. Stabilizing works in Live View... so you can use it with a video feed, and without cropping (which can't be deactivated in the K-3 when recording video, even when you're not using IS).
As for camera brands not offering useful video: Yes, Fuji, Leica and Sigma. Sigma is irrelevant, Fuji and Leica cater to a small crowd of photography purists with plenty of cash. Not the average working photographer that needs to earn a living and is asked to do stills and video.