Originally posted by rparmar One would have to compare with the A900, since there is no way I would give up 100% viewfinder in a professional full-frame body.
I think 98% is alright but I accept if it has to be 100% for you.
Originally posted by rparmar I have done this exercise, comparing the K-7 plus an optimal set of lenses (DA12-24, FA31, FA43, FA77) to the Sony A900 and a "similar" set (Vario-Sonnar T* 16-35/2.8, Sony 50/1.4, Planar T* 85/1.4, Sony 135/2.8 [T4.5]).
I'm not sure there is a better way to make this comparison but with the exception of the Sony 50/1.4 all the other Sony lenses exceed the Pentax equivalents not only in terms of speed. I'm not surprised the Sony kit turns out more expensive. Whether it should be more expensive by the amount you arrived at, that is a good question, but no doubt the equipment is better.
Also note that you are paying a premium for the A900 of ~$1000 more for 2% more viewfinder coverage and 5 FPS rather than 3 FPS. If you take away that premium, your price difference shrinks to about $2200.
Do you still have the individual prices for the lenses?
Was that before or after the Pentax lens price hike?
Is the fabled Sony 135/2.8 [T4.5] still available as new?
Originally posted by rparmar You gain a stop across the board with the Sony setup.
The Pentax 12-24/4 equivalent on FF is a 18.5-37/6.2. That's a 2.3 stop advantage for the 16-35/2.8 Carl Zeiss Sony zoom.
To take the same images which you can take with the f/1.8 Ltds on APS-C, you only need f/2.8 on FF (obviously converting the focal length as well). So if you've got an f/1.4 on FF, that's a
2 stop advantage compared to an f/1.8 lens on APS-C.
Originally posted by rparmar ...while losing out on some of the cool Pentax advantages.
It's got in-body image stabilisation and is weather-resistant. Where does it lose out, except in size (for some, that is. I find the K-7 a bit too small.)?
Originally posted by rparmar So that's the true cost of full-frame.
No, that's the true cost of an
excellent SONY full frame system. Nothing dictates that a regular FF set has to consist of very fast top-notch Carl Zeiss lenses and a unique 135 with an apodization element.
I said earlier that the cost for the really good SONY lenses is high but the kit you assembled is a hell of a kit and not representative of a regular FF kit.
As Falk (falconeye) has repeatedly pointed out the cost for FF glass can be/is lower than that of APS-C glass if you strive for the same (and not better) performance.