Archived posting to the Leica Users Group, 2009/01/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Jan 28, 2009, at 3:43 PM, Douglas Sharp wrote: > Hi, > > although I posted this only a month or so ago, here it is again: > > I never bothered to find out if it applies in manual metering mode - > does any one know if that works correctly? > > Bob Palmieri sent it to me OL in 2005 > > This is what Canon says about it: > > The EOS 20D focusing screen is optimized for superior brightness at > moderate apertures from about f/3.5 and smaller, compared to > conventional ground glass designs. This makes the viewfinder image > brighter and easier to focus at those moderate apertures, but the > trade-off is that it passes disproportionately more light to the > metering system. When a Canon EF lens is mounted to an EOS camera, a > variable exposure compensation factor (a program curve, not just a > fixed compensation factor) for this phenomenon is fed through the > system in order to provide correct metering for all apertures. > However, when using a non-coupled manual diaphragm lens as you > describe, no such communication takes place, so the responsibility > for exposure compensation reverts to you. It's unnecessary to use an > external meter. Instead, you can take a series of test shots at the > working aperture(s) you plan to use, then analyze the test photos to > determine the most desirable exposure compensation factor for each > aperture. The 20D's auto exposure bracketing (AEB) function speeds > up the process of taking the test photos, and you can use the Info > palette in Photoshop to determine the most accurate exposure. If you > can standardize on one particular aperture you plan to use (for > maximum sharpness, desired depth of field, etc.), that will simplify > the calibration process by eliminating the need for tests at other > apertures. thanks Douglas, so with Canon, aside from shooting wide open, you must calibrate/compensate, and that is a minor pita... Steve > > > Cheers > Douglas > > Steve Barbour wrote: >> >> On Jan 28, 2009, at 2:02 PM, Wayne Serrano wrote: >> >>> Luggers, >>> >>> I am inclined or maybe I should say leaning towards a Canon (full >>> frame) digital body to make use of the 28/2.8 current, 60/2.8 >>> current, 90/2.0 older, 100/2.0 Apo, and 180/2.8 APO lenses. Which >>> Canon body I have no idea.... >> >> >> I have a Canon 5D Wayne...I have used a number of Leica R lenses on >> it... >> >> remember that there are issues re progressive overexposure as you >> close down the diaphragm... >> >> I am not sure I understand why this is...help someone? >> >> it's fine if you shoot wide open, >> >> Steve >>> >>> >>> -----Original Message----- >>>> From: George Kase <gkase@ccfc.com> >>>> Sent: Jan 28, 2009 12:15 PM >>>> To: lug@leica-users.org >>>> Subject: [Leica] R lenses on any Digital body >>>> >>>> Wayne, >>>> Get any Canon EOS digital body ( I have a Digital Rebel XT) and >>>> Get an adapter for R to EOS mount and you're done. Cheap >>>> George >>>> >>>> >>>> _______________________________________________ >>>> Leica Users Group. >>>> See http://leica-users.org/mailman/listinfo/lug for more >>>> information >>> >>> >>> >>> >>> _______________________________________________ >>> Leica Users Group. >>> See http://leica-users.org/mailman/listinfo/lug for more information >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information