Archived posting to the Leica Users Group, 2004/10/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Mark Rabiner wrote: > I think all you guys have yet to hit the nail on the head on this one. > "crop factor" is a meaningful term because if you are using a 100mm > lens on > a 35mm cameras system you have lots of bodies to choose from and they > all > are normal 35mm 24x36mm format bodies. > > But if you put that lens on a body with a CCD or film even which is > APS-c > sized as most digital is and which is 25.1x16.7mm you have a 1.5 crop > factor > and a smaller needed image circle and a smaller format diagonal. > The only reason that 'crop factor' is meaningful, really, is because it is in general easier to design a particular lens having a particular resolution, etc. when the coverage is less. For example the Schneider Super Symmar XL 150/5.6 -- considered an *exceptional* super wide angle for the 8x10 format ... aspheric yada yada yada, with lots and lots of lpmm **for 8x10** but if you were to slap this on a 35mm it would be a downright dud ... super expensive, slow, low resolution etc. So basically for the APS-c factor you are 'paying for' a 35mm format lens but only the APS-c lpmm. Jonathan