(Image Source Page: http://www.pentax.jp/japan/products/645d/feature.html)
Since the 645D was announced, people, in particular Pentaxians, have been arguing about the advantages against the shortcomings of the new 645D when it is compared against other DSLRs of different sensor sizes, pixel counts and form factors. I think it would be of no harm for me to list out the factual data of some of the sensors used by some of the current popular DSLRs that could be compared, for an overview on the basic physical and specification differences, before heat debates and more discussions are to be carried on..
| Camera / Digital Back | Sensor Size (in mm) | Sensor Area (in mm^2) | Resolution | Aspect Ratio | Total Mega Pixels | Pixel Size (in um) | ISO Range |
| Pentax 645D | 44 x 33 | 1452 | 7264 x 5440 | 4 : 3 | 40.24 | 6.1 x 6.1 | 200 - 1000 (100 - 1600 Expanded) |
| Mamiya DM40 | 44 x 33 | 1452 | 7350 x 5562 | 4 : 3 | 40.88 | 6.0 x 5.9 | 80 - 800 |
| Mamiya DM56 | 56 x 36 | 2016 | 9288 x 6000 | 3.1 : 2 | 55.73 | 6.0 x 6.0 | 80 - 800 |
| Mamiya DM33 | 48 x 36 | 1728 | 6726 x 5040 | 4 : 3 | 33.90 | 7.1 x 7.1 | 50 - 800 |
| Canon EOS 1D3 / 5D2 | 36 x 24 | 864 | 5616 x 3744 | 3 : 2 | 21.03 | 6.4 x 6.4 | 1D3: 100 - 1600 (50 - 3200 Expanded) 5D2: 100 - 6400 (50 - 25600 Expanded) |
| Nikon D3X | 36 x 24 | 864 | 6048 x 4032 | 3 : 2 | 24.39 | 6.0 x 6.0 | 100 - 1600 |
| Nikon D3S / D700 | 36 x 24 | 864 | 4256 x 2832 | 3 : 2 | 12.05 | 8.5 x 8.5 | D3S: 200 - 12800 (100 - 102400 Expanded) D700: 200 - 6400 (100 - 25600 Expanded) |
| Pentax K-x | 24 x 16 | 384 | 4288 x 2848 | 3 : 2 | 12.21 | 5.6 x 5.6 | 200 - 6400 (100 - 12800 Expanded) |
So, for anyone who is interested to compare, now you can compare all these parameters and calculate their ratios and differences in percentage and etc.
Do it endlessly till the end of the days, which is just another kind of measurbation! ;-D Enjoy!