>I'm mostly view-camera illiterate, so I'm sure a more informed voice >could chime in here, but I'm seeing that "maximum coverage" is >achieved on some lenses only when stopped down significantly. On a >camera with rise, swing and tilt capability, I'm guessing that >"maximum coverage" could only be achieved with the lens and film back >parallel (I'm sure someone will correct me if that is inaccurate). > >With regard to the 35mm lenses, yes, the Pentax Forums lens database >lists the FOV for horizontal and diagnonal for both 35mm full frame >and APS-C sensors. > >Darren Addy >Kearney, Nebraska
FOV is the angle that comes in the front. Coverage is what comes out the back. The convention (there is no governments standard like "Watts RMS in 8 ohms, from 20-20000Hz" in audio) is f22 when focused @ infinity. That gives you your minimum film plane coverage for a lens. Many lenses are not sharp as they get close to the edge of coverage. That is only documented anecdotally, so it is best to have several mm extra coverage to compensate. So we use reference tables like this http://www.graflex.org/lenses/lens-spec.html to check out lens coverage. The Super Symmar XL has plenty of coverage for 8x10. https://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=169&IID=7634 But few have the wallet. :-( > The diagonal FOV on a 20mm Takumar lens is only 94 degrees, 35mm full frame > The diagonal FOV on a 15mm Takumar lens is 111 degrees, 35mm full frame. It is stamped on the lens as having 105 deg coverage. That falls somewhere in between these two focal lengths. Sincerely, Collin Brendemuehl "He is no fool who gives what he cannot keep to gain what he cannot lose" -- Jim Elliott -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
