Archived posting to the Leica Users Group, 2014/02/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Non native lenses are really easy to focus with the A7r. There's a color indicator that blooms as areas are in focus. (you can change the color of the bloom) On Sat, Feb 22, 2014 at 10:13 AM, Frank Filippone <red735i at verizon.net>wrote: > Certainly during focusing, there is little computing going on other than > focus and metering... so certainly there is power available to do more > extensive focusing operations.... > > Until someone hacks the FW, I doubt we will know much more..... > > I was just shocked about focusing at shooting aperture.... he last time I > HAD to do that was in the 60's, when my long 400mm f8 lens did not have > auto > aperture, and shooting sports was nearly impossible with the preset > aperture > rings.... With AF, it is a different animal all together.... > But I really wonder to what advantage there is to native lenses when you > have an EVF that takes care of finder brightness, and AF that for native > lenses is done at shooting aperture... It seems to be the same if you were > to use non-native lenses... With the exception of AF itself......... > > Frank Filippone > Red735i at verizon.net > > > -----Original Message----- > From: lug-bounces+red735i=verizon.net at leica-users.org > [mailto:lug-bounces+red735i=verizon.net at leica-users.org] On Behalf Of > Sonny > Carter > Sent: Saturday, February 22, 2014 7:22 AM > To: Leica Users Group > Subject: Re: [Leica] OT - Sony Alpha 7R > > I was thinking about the event on the FE lenses where they focus at working > aperture, and at focus, they open about a half stop during the AF portion > of > the program. > > Perhaps the camera compares the different depth of field at each aperture > to determine final calibration? Most of the details needed to calibrate > the > lens might be stored in the lens' chip at manufacture. > > Judging from what I can see in the viewfinder when I have all the info > turned on, the camera is capable of considerable computing power. > > > > > On Sat, Feb 22, 2014 at 8:57 AM, Frank Filippone <red735i at verizon.net > >wrote: > > > The camera is open loop.... meaning that there is no comparison upon > > which to base a standard for what is in focus during calibration. In > > real world terms, your eyes and brain decide what is actually in > > focus. So the camera, by itself, would not be able to do the > > calibration. ( why there really is a fine focus adjust feature in > > higher end cameras.. camera AF is adjusted by the user to nail down > > the precise focus location. > > > > If you used a computer and factory "machines" to do the calibration, > > it would be relatively trivial to imbed the calibration data into the > > lens ROM and have the camera access that info, perform modification to > > the camera to produce "correct" focus .... if the camera is > > calibrated.... which, even in the case of Leica, is not always > > correct.... > > > > In truth, the idea is a good one.... but requires the manufacturer to > > calibrate each lens and embed the error-correcting-calibration, and > > each camera body to a standard....and then to design FW to allow the > > access and use of that data..... Read all of that as extra cost, and > > you get an idea of why it has not been done yet.... > > > > If you go to the Sigma site, and read about their whoopee doo new > > lenses ( I think they are the ART lenses), you will read about a > > little gadget that allows each AF lens + camera to have its errors > > embedded into the lens for correction upon use..... The customer gets > > to do the work..... Cost is pretty mild, work time is a few minutes > > per lens... It is pretty close to your suggestion.... > > > > Frank Filippone > > Red735i at verizon.net > > > > > > -----Original Message----- > > From: lug-bounces+red735i=verizon.net at leica-users.org > > [mailto:lug-bounces+red735i=verizon.net at leica-users.org] On Behalf Of > > Sonny Carter > > Sent: Friday, February 21, 2014 10:58 PM > > To: Leica Users Group > > Subject: Re: [Leica] OT - Sony Alpha 7R > > > > So how can you know how it doesn't do it and not know how it does it > > at the same time? ;-) > > > > Sent from my iPhone > > > > Sonny Carter > > http://www.SonC.com/look > > > > > > > On Feb 21, 2014, at 11:56 PM, "Frank Filippone" > > > <red735i at verizon.net> > > wrote: > > > > > > You would need a reference calibration somewhere...and to be honest, > > > the camera does NOT know what is actually in focus and what is not.... > > > it only knows what should be in focus.... it is an open loop system.... > > > > > > Would you like to sit there at every F stop (and FL for a zoom) and > > > calibrate the focus shift for every combination? > > > > > > This is a factory calibration, not a user calibration > > > > > > Frank Filippone > > > Red735i at verizon.net > > > > > > > > > -----Original Message----- > > > From: lug-bounces+red735i=verizon.net at leica-users.org > > > [mailto:lug-bounces+red735i=verizon.net at leica-users.org] On Behalf > > > Of Sonny Carter > > > Sent: Friday, February 21, 2014 9:49 PM > > > To: Leica Users Group > > > Subject: Re: [Leica] OT - Sony Alpha 7R > > > > > > Couldn't the camera calibrate the lens? After all, it is an optical > > > computer; what is one more task added? > > > > > > Sent from my iPhone > > > > > > Sonny Carter > > > http://www.SonC.com/look > > > > > > > > >>> On Feb 21, 2014, at 11:37 PM, "Frank Filippone" > > >>> <red735i at verizon.net> > > >> wrote: > > >> > > >> That would require calibration of each lens ( maybe they all act > > >> the same????)... > > >> > > >> I would think of this as a really good idea, but I also thought a > > >> R10 was a really good idea...... > > >> > > >> Frank Filippone > > >> Red735i at verizon.net > > >> > > >> > > >> Frank Filippone wrote: > > >> > > >>> > > >>> If you are focusing at working aperture, what advantage is there > > >>> to native lenses? > > >>> > > >>> I'm not so sure Sony has this thought out...... > > >> > > >> For those who are interested in such things, native-mount lenses > > >> will allow shutter-priority and program exposure modes, and AF. > > >> > > >> Another way to handle focus shift would be to program the lens to > > >> tell the camera how much shift there is at various apertures. > > >> Given this would be a native-mount lens the camera would know what > > >> aperture the lens will be using. > > >> > > >> Doug Herr > > >> Birdman of Sacramento > > >> http://www.wildlightphoto.com > > >> > > >> > > >> > > >> > > >> _______________________________________________ > > >> 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 > > > > > > _______________________________________________ > > Leica Users Group. > > See http://leica-users.org/mailman/listinfo/lug for more information > > > > > > -- > Regards, > > Sonny > http://sonc.com/look/ > Natchitoches, Louisiana > 1714 > Oldest Permanent Settlement in the Louisiana Purchase > > USA > > _______________________________________________ > 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 > -- Regards, Sonny http://sonc.com/look/ Natchitoches, Louisiana 1714 Oldest Permanent Settlement in the Louisiana Purchase USA