Archived posting to the Leica Users Group, 2014/02/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]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