Originally posted by Fauxton Actually Mike the reason why the K5 sensor performs well is not that it is particularly low in read noise. In fact the K3 has lower read noise as does the KP. The reason for the K5's fairly wide DR relative to the K3 is due to its saturation value. Its Quantum Efficiency is about the same. As to the K7 its read noise is quite high - almost 6 times higher than the K3 and K5 while at the same time having a significantly lower QE and about the same sensor saturation as the K3 (about 60% of the K5). The K5 can make use of a 14 bit ADC as its DR at base ISO (~13.8 stops) is above what a 12 bit convertor would convert comfortably as base ISO. The K7 at roughly 10.2 stops of DR at base ISO will fit well with a 12 bit ADC. Someone above mentioned that the K20D; it has lower read noise than the K7 but it has roughly the same sensor saturation and QE. That gives is a slight bit better DR. Not really much to matter though - its about a third of a stop better.
Very interesting. How you are able to gain this technical information is mystifying, but your insights are impressive. Upon re-reading, what I notice is the evaluated differences between these models closely resembles my own judgments and impressions, either from tests I have read or from personal experiences. I have never used a K-7.
For years, it was a given that going to a design of higher MPs would include a greater noise factor, and the need for greater noise suppression with detail-smearing side-effects. Many people were sticking to their 6mp DSLRs. The K10D and K200D came along with advanced features, and at 10MP noise control was pretty good with good detail preservation. The K20D was a surprise in that noise control factors were still decent despite increasing resolution to over 14 MP. The K-5 was a shocker. It seemed achieving such outstanding noise control with good detail preservation in a DSLR of more than 15MP was miraculous! Now we have even better results in the K-70 and KP at 24MP! I have always thought if sensor technology can be advanced to create less noise to begin with, we would not require as much NR and get much cleaner results at higher ISO settings. I think we still have more room for improvement here, but what we now have is amazing. I still value my K-5 IIs greatly for its controls, fine IQ, excellent build and ergonomics, relatively low weight, and fine handling. Even though it has now been surpassed, it is capable of very high-quality images. Between it, my KP, and K-S2, it is more about what features I will need, how high the ISO I might need, and the practical aspects of portability, etc. So far, I have found the KP to be truly outstanding in many aspects.