sparkie Posted January 30, 2007 Share #1 Â Posted January 30, 2007 Advertisement (gone after registration) Just wondered if the f stop is recorded on the M8 with lenses with are encoded. I assume it is not or not capable of knowing. All my shots on the 28/2.8 ASPH only show that the shutter speed and lens. But no f-stop details. Is this normal? Link to post Share on other sites More sharing options...
Advertisement Posted January 30, 2007 Posted January 30, 2007 Hi sparkie, Take a look here M8 Lens detection, EXIF and 6-bit encoding. I'm sure you'll find what you were looking for!
Eoin Posted January 30, 2007 Share #2 Â Posted January 30, 2007 No the actual f/stop is not recorded, only the maximum(fastest) aperture of the lens is recorded in EXIF. This is the limit as there is no communication of the aperture used during exposure from lens to camera(manual lenses). Link to post Share on other sites More sharing options...
sparkie Posted January 30, 2007 Author Share #3 Â Posted January 30, 2007 ok thank Eoin. I dont think that the max f-stop is even recorded (from memory) Link to post Share on other sites More sharing options...
jaapv Posted January 30, 2007 Share #4 Â Posted January 30, 2007 Actually the f-stop used is deduced by the camera from the "blue spot"sensor, and used for vignetting correction on coded lenses, but as it is not completely accurate it is not recorded in Exif. Link to post Share on other sites More sharing options...
johnll Posted January 30, 2007 Share #5 Â Posted January 30, 2007 No the actual f/stop is not recorded, only the maximum(fastest) aperture of the lens is recorded in EXIF. This is the limit as there is no communication of the aperture used during exposure from lens to camera(manual lenses). There is, however, apparently an estimate of the aperture that is used for vignetting and related corrections. This is not recorded in the EXIF data, but I imagine it could be, and believe it could be useful if it was. This estimate is apparently derived via the "blue dot" sensor that measures overall subject brightness. Presumably the firmware considers ISO setting, shutter speed and exposure compensation in determining the approximate aperture. Â Jaap beat me to it! Link to post Share on other sites More sharing options...
Eoin Posted January 30, 2007 Share #6 Â Posted January 30, 2007 ok thank Eoin. I dont think that the max f-stop is even recorded (from memory) Â Â It shows up in my Exif data Link to post Share on other sites More sharing options...
scott kirkpatrick Posted January 30, 2007 Share #7  Posted January 30, 2007 Advertisement (gone after registration) It shows up in my Exif data  where? C1's rather limited ctl-I output doesn't show the lens's widest aperture. irfan view just shows the max aperture as f/1.0 which is a sort of default.  scott Link to post Share on other sites More sharing options...
sparkie Posted January 30, 2007 Author Share #8 Â Posted January 30, 2007 what software are you using to view your EXIF data? Â I'm looking in photoshop CS2 under File info > "camera data" and it says Max aperture value: f1.0 ! Link to post Share on other sites More sharing options...
Eoin Posted January 30, 2007 Share #9  Posted January 30, 2007 You guy's are really trying to give me an alzheimer panic attack  If your lens is properly coded the information relating to maximum aperture is recorded in the Exif info. I began to doubt my self and checked the Exif info on some leica coded lens shots, a 75 Summicron and 21 Elmarit. I checked in C1 Pro, CS2 and Aperture. All correctly report the maximum aperture as f/2 for the Summicron and f/2.8 for the Elmarit. I've just done this now so I'm not imagining that it's there.  The only time I have seen the f/1.0 is when the lens detection is switched off or the lens is not properly "locked" into place giving a the default f/1.0. Or if the lens is not coded at all.  If you have any home coded lenses you should be able to test the accuracy of your marks by reviewing the image on the camera screen and pressing info. You should then see the lens focal length and the maximum aperture displayed, if the max aperture is not displayed the camera did not pick up the code correctly or the code is out of alignment. Therefor this may be the reason your C1 Pro or CS2 is showing f/1.0.  Have a look again, Link to post Share on other sites More sharing options...
sparkie Posted January 30, 2007 Author Share #10 Â Posted January 30, 2007 I checked and opened some more files shot the other day. And I looked again at the bottom of my 28/2.8ASPH and it definitely has the 6-bit coded dudad. and I distinctly remember turning ON lens detection in the menu. The weird this is that CS2 is showing that it is a focal lenght of 28.0 mm so in some way the lens detection is working, but no max f-stop acknowledgement. contrast this to a 35/1.4 uncoded lens which shows nothing but shutter speed and ISO speed ratings with a max aperture value of f1.0. Â And YES, I remembered to take my pills this morning. So I'M not imagining this either! maybe something is wrong with my came (apart from the stuck VF framelines) *sigh* Link to post Share on other sites More sharing options...
cbretteville Posted January 30, 2007 Share #11 Â Posted January 30, 2007 Somwhere in the back of my mind I seem to recall the max fstop being stuck at 1.0 is one of the bugs that have been mentioned before - at least for the 35'luxASPH. Could apply to other lenses as well. Supposedly it will be fixed in 1.10. - C Link to post Share on other sites More sharing options...
sparkie Posted January 30, 2007 Author Share #12 Â Posted January 30, 2007 my 35/1.4 lens is uncoded so the zero data is expected. but there is an anomoly with my 28/2.8ASPH which is definitely zebra'd Link to post Share on other sites More sharing options...
cbretteville Posted January 30, 2007 Share #13 Â Posted January 30, 2007 The data coded in the exif is just a value read out of a table based on the lens code. If the data in the table is wrong it will be wrong in the exif as well. I'll have a look at the table in the v1.09 image and see if I can figure it out for the 28/2.8. Link to post Share on other sites More sharing options...
Eoin Posted January 30, 2007 Share #14  Posted January 30, 2007 I checked and opened some more files shot the other day. And I looked again at the bottom of my 28/2.8ASPH and it definitely has the 6-bit coded dudad. and I distinctly remember turning ON lens detection in the menu. The weird this is that CS2 is showing that it is a focal lenght of 28.0 mm so in some way the lens detection is working, but no max f-stop acknowledgement. contrast this to a 35/1.4 uncoded lens which shows nothing but shutter speed and ISO speed ratings with a max aperture value of f1.0. And YES, I remembered to take my pills this morning. So I'M not imagining this either! maybe something is wrong with my came (apart from the stuck VF framelines) *sigh*  I think the info for the lens focal length is a combination of the 6bit and the frame lines, for example before I coded my 35'lux it showed up as 35mm with max aperture of f/1.0. I have noticed something funny with this lens after coding the max aperture would show in the exif data as f/2.0 within Aperture but show f/1.4 on the camera. I'll have to check this one again and see what it's showing now (the old memory is in serious doubt today). I know for sure the 50 Summicron is not coded but it shows up as 50 f/1.0.  Do you have any pills to spare? !! Link to post Share on other sites More sharing options...
jaapv Posted January 30, 2007 Share #15 Â Posted January 30, 2007 It is clearly a 1.09 firmware bug. My first gen camera did it correctly on 1.06, and has reverted to recognizing only the focal length on its conversion to 1.09. There seems to be no difference whatever in the practical result on the file however. I suppose it will be fixed in 1.10. Link to post Share on other sites More sharing options...
Leicaiste Posted January 30, 2007 Share #16 Â Posted January 30, 2007 There is a bug in the 1.09 about the 28/2,8 Asph coding. The maximum aperture is not showing. Link to post Share on other sites More sharing options...
sparkie Posted January 30, 2007 Author Share #17  Posted January 30, 2007 thanks for the clarification guys  Eoin, I have plenty of pills. what colour would you like !? Link to post Share on other sites More sharing options...
danielt Posted January 30, 2007 Share #18 Â Posted January 30, 2007 Exif for TE coded show f4 as max aperture (O.K.) Exif for 28 / 2.8 Asph coded show f1 as max aperture (wrong) Â M8 2nd batch, firmware 1.09 Link to post Share on other sites More sharing options...
jaapv Posted January 30, 2007 Share #19 Â Posted January 30, 2007 24 shows up as 1.0 Link to post Share on other sites More sharing options...
Eoin Posted January 30, 2007 Share #20  Posted January 30, 2007 thanks for the clarification guys  Eoin, I have plenty of pills. what colour would you like !?  "You take the red pill and you stay in Wonderland and I show you how deep the rabbit-hole goes. (Long pause; Neo begins to reach for the red pill) Remember -- all I am offering is the truth, nothing more."  I saw what happened to him , I'll take the blue one, thanks. But not a diamond shaped one. Link to post Share on other sites More sharing options...
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