Originally posted by rawr Not quite the full story. It's all about sensor data going into the [PRIME IV] image processing chip, associated circuitry, and RAM, then finding it's way out as RAW's or JPEGs onto a SD card. Not just the sensor read-out speed.
Firmware can help a LOT with fps rates. As other brands illustrate, for RAW shooting you can change the achievable fps by just altering the recorded bit depth of your RAW's (eg 12/14 bit), and/or the compression level and type of compression applied to your RAW's.
And one only has to remember the impact of K-5 firmware v1.01, which auto-magically boosted the K-5's continuous shooting RAW buffer from a maximum of approx. 8 frames to approx. 20 frames. Just via software.
Firmware has a lot of potential to upgrade how well the hardware works with todays portable computers with lenses. Oops, I mean todays digital cameras.
The fps rate doesn't go as far as "finding it's way out as RAWs or JPEGs onto a SD card".
Lowering the bit depth helps by reducing the amount of data to be transferred for each frame. Compression level would work only if done on the sensor. Boosting the RAW buffer might be an indication of on the fly compression, or not - in any case, the fps remained the same.
The sensor could be "overclocked" to some extent but I assume the hardware must support it as well. In the end, the possibilities of speeding up sensor read-out via a firmware update are limited, and of limited effect.
In any case, the D810 supports up to 5fps - not such a big difference, compared to the K-1's 4.4. Even in crop mode, we're talking about 7 fps compared to the K-1's 6.5.
IMO there aren't "some extra FPS" to gain, by any reasonable method. I would like that for sure, but it'll have to wait for a new model/hardware.