Sony A850 has a
25.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor and features Bionz processor. On the other hand, Pentax K-1 has a
36.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor .
Pentax K-1's sensor provides 11MP more than Sony A850's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
One other difference between these two cameras that is worth mentioning is that Pentax K-1's sensor doesn't have an anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the A850 and K-1 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A850 and Pentax K-1 Cameras
Sony A850 and Pentax K-1 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Sony A850 has 48% larger pixel area compared to Pentax K-1, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Sony A850 and Pentax K-1 sensors have been tested by DxO and the results show that K-1 has a better overall score of 96, 17 points higher compared to A850's score of 79.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A850
79
23.8 bits
12.2 Evs
1415 ISO
Pentax K-1
96
25.4 bits
14.6 Evs
3280 ISO
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Sony A850
or the
Pentax K-1 ,
including hyperfocal distance.
