On 09/10/2004, at 6:17 PM, prodig-digest wrote:
� Full Frame RGB square-structured 48 x 36 mm CCD
although that doesn't sound full frame but have never owned or
measured
a 645 neg/tranny...
Sadly, I have - Bronica ETRS gave me 58 x 42mm
So a quick guess means the 35mm lens which is the widest 645 is only
about the equivalent of 32mm on a 35mm SLR....oh dear! Why do wide
angles always get forgotten :-(
Simply divide the long dimension of the sensor by the long dimension of 35mm film then divide 1 by that.
So 48 divided by 36 = 1.3 recurring = 1/1.3 = 0.75
This is your lens modifier. As many of you would know you simply multiply the lens focal length by the lens modifier.
Therefore for the 35mm Mamiya lens:
35mm multiplied by 0.75 gives a 26.25 mm film equivalent for the 48mm dimension of the sensor.
The multiplier for the 645 were you using using ordinary film (60mm divided by 36mm = 1.66 = 1/1.66 = 0.6) is as follows.
A 35mm lens on the 645 as a film camera is equivalent to (35*0.6) or 21mm on a camera that uses 35mm film.
Unless I am wrong, it is early here ;-)
Doug
