Hi folks! A confusing question came to me:
To have FF equivalent focal length of a lens for our APS-C sensors, we have to apply a factor of 1.6x: 40mm f/2.8 ltd is a 64mm FF equivalent. For the depth of field, this factor is to be applied too: 40mm 2.8 ltd is a 64mm f/4.5 FF equivalent. But, what about the amount of light? As the surface divide by 1.6x1.6 and the sensor is placed at the same distance as a FF SLR film, the light reaching the sensor is divided by the same amount: 2.56. Are the ISO from FF, APS-C, m4/3, P&S all the same, or are they equivalent ones to take crop factor into account? Concerning light, is the 40mm 2.8 ltd, a true f/2.8 opened lens, then? ~Alban. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
