Bo_Lorentzen Posted November 18, 2009 Share #1 Â Posted November 18, 2009 Advertisement (gone after registration) Did anyone notice, Â Under meta tags. exposure 1/20 f5.6 (not the lens speed) Â Apparently Leica have given Adobe access to the G.stop info. Â . Link to post Share on other sites More sharing options...
Advertisement Posted November 18, 2009 Posted November 18, 2009 Hi Bo_Lorentzen, Take a look here Lightroom 3 beta - show g-stop for M9. I'm sure you'll find what you were looking for!
Jager Posted November 18, 2009 Share #2 Â Posted November 18, 2009 Er, well, I know what a G-spot (what came up when I googled "g stop") is when referring to the distaff part of our population. Â But I'm at a loss as to what it means photographically. Can you enlighten, Bo? Link to post Share on other sites More sharing options...
Bo_Lorentzen Posted November 18, 2009 Author Share #3 Â Posted November 18, 2009 Jeff, Â Sorry, short for guess f.stop - the camera actually record a "guess" at the aperture used for each shot, based on the light measured on the outside sensor, the lens type (from the 6bit coding), the shutter speed and the amount of light actually being recorded behind the lens. Â The corner fix software have been reading this for a while, but apparently Adobe have now included it in the 3.0 version. Â It is not a accurate aperture, but seems to be very close in most cases. Â I am wondering if this is all Leica shared with Adobe when they made LightRoom the official M9 software, one could hope they gave a little more when they got in bed with lightroom and we will in the future see lightroom perform better DNG conversions closer to PhaseOne. Â . Link to post Share on other sites More sharing options...
Jager Posted November 18, 2009 Share #4 Â Posted November 18, 2009 Ah, that makes sense. Thanks Bo. Â Having even the guestimated f-stop embedded in the EXIF (and readable by Lightroom) will be very nice. I've heard that it's generally pretty reliable. Link to post Share on other sites More sharing options...
rsmphoto Posted November 18, 2009 Share #5 Â Posted November 18, 2009 That explains I was seeing Æ’1.5 as my aperture when shooting wide open with my 35 lux. I figured it was a bug. Link to post Share on other sites More sharing options...
Bo_Lorentzen Posted November 18, 2009 Author Share #6 Â Posted November 18, 2009 Very practical feature. Â Keep in mind that the sensor on the front of the body is involved as that is how they get the ambient exposure. So if that sensor is hit by direct light and you are exposing for a back-light portrait... well there are no way it is going to get it right, unless you also shade the sensor to protect it from the direct light... Â Problem areas will be contrasty side light, and backlight mostly. Â Still - Im delighted to have a rough indicator of what I was doing... and since I mostly shoot at max aperture or stop down to 5.6 (further for some product shots) its pretty easy to know where I really were.. Â . Link to post Share on other sites More sharing options...
Mauribix Posted November 18, 2009 Share #7 Â Posted November 18, 2009 Advertisement (gone after registration) That explains I was seeing Æ’1.5 as my aperture when shooting wide open with my 35 lux. I figured it was a bug. Â Actually there's a bug... Reading is often inaccurate, because LR3beta is reading the "right" tag in the file's exif, but it's not applying the right calculation. That should be fixed in the next releases. Link to post Share on other sites More sharing options...
Mauribix Posted November 18, 2009 Share #8 Â Posted November 18, 2009 We discussed that here: http://www.l-camera-forum.com/leica-forum/digital-post-processing-forum/103207-lightroom-3-beta-released.html#post1088475 Link to post Share on other sites More sharing options...
rsmphoto Posted November 19, 2009 Share #9 Â Posted November 19, 2009 Thank you! That clarifies things. Link to post Share on other sites More sharing options...
spersky Posted November 19, 2009 Share #10 Â Posted November 19, 2009 Lol thanks. I was wondering why I was seeing f/1.5 on some of my pictures. Also, I had one that was f/1.0. I did not know I had a Noctilux. Link to post Share on other sites More sharing options...
mat_mcdermott Posted November 19, 2009 Share #11 Â Posted November 19, 2009 M8 files also show an f-stop in LR3, FWIW Link to post Share on other sites More sharing options...
scott kirkpatrick Posted November 19, 2009 Share #12  Posted November 19, 2009 This story goes back a while. I don't have an M9 yet (it's in the mail), but from the M8 days, Carl Bretteville found that there were three pieces of information hidden in the MakerNotes (private, not documented) section of the EXIF of every DNG file  the exposure reading of the blue dot in EV units  the exposure reading inside (TTL) in EV units  and Leica's estimate of the actualy lens aperture, calculated by taking the difference of the first two items, applying some standard offset, converting to f-stops. If the lens type is detected and its max and minimum aperture is tabulated, then the Leica estimated aperture is clipped to the max or min value when it exceeds one of them. The Leica estimated aperture (called by some the g-stop) tends to be a half stop high in the M8, for unexplained reasons. Sandy McGuffog in Cornerfix prints Leica's and his own estimates (typically half a stop lower) in the Cornerfix log file. Phase One, with the help of both Leica and Carl's memo (see his website http://www.Bretteville.com for the original memo including experiments to find the best g-stop estimator).  For the M9, the MakerNotes are much richer and harder to decode. Bravo to LR for getting Leica to explain things to them. Perhaps someone will whisper the same information to Phase One and Aperture soon...  scott Link to post Share on other sites More sharing options...
cbretteville Posted November 20, 2009 Share #13 Â Posted November 20, 2009 I actually think Sandy is the one that got Adobe to see the light. There was an email exchange I was part of where Adobe wanted to know if the information was 'for real'. I have no idea if Leica actually confirmed it to them, but I know they got code from Sandy that was based on my research. Â Great that Adobe has added it. If someone don't like the fact that the info isn't 100% accurate I advise them to simply ignore the data as displayed. It is the best we can do as long as there is no aperture feedback from the M-lenses. Â Carl Link to post Share on other sites More sharing options...
sandymc Posted November 20, 2009 Share #14 Â Posted November 20, 2009 What build number do folks have that shows g-stop for the M9? Â My LR3 beta (build 618187) shows it for the M8 (incorrectly!), but not the M9......... Â Sandy Link to post Share on other sites More sharing options...
Bo_Lorentzen Posted November 20, 2009 Author Share #15 Â Posted November 20, 2009 Thats the build I have, and it show 1/30 f.4 have only imported M9 files so far (no M8) Link to post Share on other sites More sharing options...
sandymc Posted November 20, 2009 Share #16 Â Posted November 20, 2009 Ok, it shows sometimes and sometimes not. Interesting. Â Sandy Link to post Share on other sites More sharing options...
adan Posted November 20, 2009 Share #17 Â Posted November 20, 2009 Hmmm- not using LR, but Bridge CS4 is showing a guess-stop. I just updated to the beta of ACR 5.6 (M9 proflie included), and I don't think the g-stop was showing before that update, but can't remember for certain. Â Seems to be within a stop of the aperture I actually used - just. My 35 f/1.4, in shots I know were f/1.4, get recorded as everything from f/1 to f/1.5 to f/2 (and occasionally "---" which may mean the value came out brighter than f/1.0 and was thus "undefined"). Â Still no serial number, though.... Link to post Share on other sites More sharing options...
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