arthury Posted January 11, 2007 Share #1 Â Posted January 11, 2007 Advertisement (gone after registration) May be I have found out why the AWB behaves differently in the same shot for the M8 ... Â I just tested 2 shots after coding my 90mm Summicron APO: both from the same spot without changing anything except ... one was metered against the subject and the other was meter on something else near the edge of the subject + exposure-locked before composing the image. Â So, in short, looks like the AWB is decided when you lock the metered exposure values while in the Japanese DSLR world, the AWB is decided when the shutter is tripped. In the DSLR world, locking the exposure does not lock the AWB. Â Can anyone else confirm this? Link to post Share on other sites More sharing options...
Advertisement Posted January 11, 2007 Posted January 11, 2007 Hi arthury, Take a look here M8: AWB --- possible explanation. I'm sure you'll find what you were looking for!
Mark_Rinella Posted January 11, 2007 Share #2 Â Posted January 11, 2007 Given that the M8 does not have an external white balance sensor, this can only be part of the explanation. Some component of white balance is not decided until the image is captured by the Kodak CCD. Link to post Share on other sites More sharing options...
marknorton Posted January 11, 2007 Share #3 Â Posted January 11, 2007 Arthur, that would require the light meter to evaluate colour as well as light intensity. I've never read anything to suggest that it does this. And what about manual exposure where there is no AE lock? Link to post Share on other sites More sharing options...
arthury Posted January 11, 2007 Author Share #4 Â Posted January 11, 2007 Arthur, that would require the light meter to evaluate colour as well as light intensity. I've never read anything to suggest that it does this. And what about manual exposure where there is no AE lock? Â Mark, Â That's a good point but I am just sharing my empirical experiences --- no real hypothesis yet ... just reporting what I found. Â Following up with what you said, I really wonder what the light-sensor near the red Leica dot does besides metering lighting conditions. Leica's manual did not seem to delve too deep into it. Link to post Share on other sites More sharing options...
marknorton Posted January 11, 2007 Share #5 Â Posted January 11, 2007 Well of course there are persistant rumours about what the blue dot does and it may be the ambient light level it measures is one more input to the de-vignetting process which as we know is mainly for wide-angles and it may be in this situation, it's more reasonable to use it to try to estimate shooting aperture. Â If that's the case, mounting a coded 21mm lens on the camera and fooling the sensor by shing a light into it should show some differences in the vignetting correction. It's definitely used to set the brightness of the LED display in the viewfinder. Â Whether we'll ever see "estimated shooting aperture" in the EXIF data is another matter. Link to post Share on other sites More sharing options...
rvaubel Posted January 11, 2007 Share #6  Posted January 11, 2007 Well of course there are persistant rumours about what the blue dot does and it may be the ambient light level it measures is one more input to the de-vignetting process which as we know is mainly for wide-angles and it may be in this situation, it's more reasonable to use it to try to estimate shooting aperture.  If that's the case, mounting a coded 21mm lens on the camera and fooling the sensor by shing a light into it should show some differences in the vignetting correction. It's definitely used to set the brightness of the LED display in the viewfinder.  Whether we'll ever see "estimated shooting aperture" in the EXIF data is another matter.  Mark  You know that Blue Dot thing is a lot of work to go to just for setting the brightness of the display. I have a hunch that the Blue Dot was supposed to play a role in many, if not all, of the conjectures that we have come up with, but they just ran out of time to implement them. Perhaps in the future when they have solved more oressing problems  Rex Link to post Share on other sites More sharing options...
devils-advocate Posted January 11, 2007 Share #7 Â Posted January 11, 2007 Advertisement (gone after registration) I am positive that the "dot" window is in fact part of the WB process -- on the weekend I was out shooting and ended up with two totally different WBs for two frames of the same subject taken seconds apart. The difference? My gloved finger covered part of the little window on the front of the camera for one shot, and not the other...... Link to post Share on other sites More sharing options...
ho_co Posted January 11, 2007 Share #8 Â Posted January 11, 2007 And I understand that Nikon's D2 series uses an external sensor to help set WB as well. Â But I don't see how determining WB from anything not in the image space could be helpful. Â And how is it that other cameras--D200, R9/DMR, Digilux 2 etc--do a decent to excellent job without external sensors? Link to post Share on other sites More sharing options...
jaapv Posted January 11, 2007 Share #9 Â Posted January 11, 2007 The Digilux2 has an external WB sensor - which works exceedingly well. Link to post Share on other sites More sharing options...
marknorton Posted January 11, 2007 Share #10  Posted January 11, 2007 Mark You know that Blue Dot thing is a lot of work to go to just for setting the brightness of the display. I have a hunch that the Blue Dot was supposed to play a role in many, if not all, of the conjectures that we have come up with, but they just ran out of time to implement them. Perhaps in the future when they have solved more oressing problems  Rex  Rex, I agree with you, the viewfinder brightess in an M7 is handled by a sensor in the viewfinder and it is a lot of work for it just to do that. WB, flash metering, viewfinder brightness, aperture estimation. All of those could use the sensor... Link to post Share on other sites More sharing options...
ed_oneal Posted January 11, 2007 Share #11 Â Posted January 11, 2007 Has anyone ever asked Leica just what the "Blue Dot" does? Link to post Share on other sites More sharing options...
ho_co Posted January 11, 2007 Share #12 Â Posted January 11, 2007 The Digilux2 has an external WB sensor - which works exceedingly well. Jaap--Thanks for the correction! Â --HC Link to post Share on other sites More sharing options...
rvaubel Posted January 11, 2007 Share #13 Â Posted January 11, 2007 Has anyone ever asked Leica just what the "Blue Dot" does? Â Yes. But the answers are ambiguous. I firmly believe that the marketing people don't know what the Blue Dot does. Actually, I firmly believe a lot of the Senior Management people don't understand the technical issues of the camera. This isn't a slam against Leica per se. That's just the way things work (or don't work). Â Rex Link to post Share on other sites More sharing options...
rvaubel Posted January 11, 2007 Share #14 Â Posted January 11, 2007 I am positive that the "dot" window is in fact part of the WB process -- on the weekend I was out shooting and ended up with two totally different WBs for two frames of the same subject taken seconds apart. The difference? My gloved finger covered part of the little window on the front of the camera for one shot, and not the other...... Â Really, someone that has a camera (not me:mad: ) needs to confirm this. But the camera has to be on a tripod to eliminate any possibly shift of view. There has to be some explenation of why the white balance jumps all over the place and maybe this is part of it. Â Rex Link to post Share on other sites More sharing options...
ed_oneal Posted January 11, 2007 Share #15 Â Posted January 11, 2007 Maybe Sean Reid could get a straight answer from the technical people in Solms. Sean? Link to post Share on other sites More sharing options...
j_w_davies Posted January 11, 2007 Share #16 Â Posted January 11, 2007 The Digilux2 has an external WB sensor - which works exceedingly well. Â No it doesn't. It usually gets it wrong in non-natural light. Link to post Share on other sites More sharing options...
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