I encountered this calculation in a Japanese site. There is nothing special about this itself but I found it interesting that the pixel pitch/area of K100D is pretty good in relation to FF 5D. In terms of pixel pitch alone, 4/3 obviously has disadvantage (I know image quality is not a matter of pixel pitch alone). Some of the mathematical symbols may not be copying well here (originally in Japanese) but you get an idea.
Ken Calculation of pixel pitch fr= focal length at wide end ff= 35mm equivalent focal length at wide end ａ＝ aspect ratio, 3/4＝0.75 or 2/3=0.66 p = effective pixel count diagonal length of image in mm d＝43.3×ｆｒ÷ｆｆ image width ｗ＝√（ｄ＾２÷（a^2+1）） area per pixel a=ｗ×ｗ÷ｐ pixel pitch ＝√ａｗ×ｗ÷ｐ area ＝√（ａ×d^2÷（a^2＋１）÷ｐ） Example of Calculation １. Fuji Finepix F10 ｆｒ＝8.0 ｆｆ＝36.0 a=0.75 ｐ＝6300000 pixel d=43.3×8 ÷36＝9.62mm w＾２＝92.587÷1.5625＝59.25568 pitch=√(0.75×59.25568 ÷6300000）＝2.65 micron. area 7.02 square micron ２. Olympus μdigital 800 ｆｒ＝8.0 ｆｆ＝38.0 a=0.75 ｐ＝8000000 pixel d=43.3×8÷38＝9.12mm w＾２＝83.1÷1.5625＝53.18 pitch=√(0.75×53.18 ÷8000000）＝2.21 micron. area 4.88 square micron ３. Olympus E-330 a=0.75 ｐ＝7500000 pixel d=21.6mm w＾２＝468.29÷1.5625 ＝299.7 pitch=√(0.75×299.7÷7500000）＝5.47 micron. area 29.9 square micron ４．Olympus E-500 a=0.75 ｐ＝8000000 pixel d=21.64mm w＾２＝468.29÷1.5625 ＝299.7 pitch=√(0.75×299.7÷8000000）＝5.30 micron. area 28.1 square micron ５. Canon EOSKissDigitalN a=0.6666 ｐ＝8000000 pixel d=26.68mm w＾２＝711.88 ÷1.4444＝492.855 pitch=√(0.6666×492.855÷8000000）＝6.40 micron. area 41.0 square micron ６. Pentax K100D a=0.6676 ｐ＝6100000 pixel d=√(23.5^2+15.7^2)＝28.26mm w ＝23.5mm pitch=√(23.5×15.7÷6100000)＝7.78 micron. area 60.48 square micron ７. Canon EOS５D a=0.6676 ｐ＝12800000 pixel d=43.04mm w＾２＝1852.44 ÷1.44569＝1281.35 pitch=√(0.6676×1281.35÷12800000）＝8.17 micron. area 66.8 square micron -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
