Reply to thread

Message: <blockquote data-quote="aroy" data-source="post: 476613" data-attributes="member: 16090">I think that "Equivalence" thing has confused the issue. A 300mm focal length remains the same whether it was designed for a 3x4mm sensor of a cell phone or for a 8"x10" large format camera. What changes is the Image Circle which for a 3x4mm sensor need not be more than 5mm dia, but has to be at least 30mm for DX, 45mm for FF, 85mm for MF and 330mm for an 8"x10".What a larger Image Circle entails is more glass in front and a more complicated design, hence more cost. That is why a lens designed for a particular sensor size (and a given maximum aperture) is the least cost option. As has been said a number of times is that as you decrease the sensor size only FOV changes. As smaller sensors are denser, you get more details, which gives us the "magnification".</blockquote>