CheshireCat Posted September 16, 2014 Share #121 Posted September 16, 2014 Advertisement (gone after registration) No optical difference. Thanks. So why this "Version II" thing ? Link to post Share on other sites More sharing options...
Advertisement Posted September 16, 2014 Posted September 16, 2014 Hi CheshireCat, Take a look here 75mm APO depth of field. I'm sure you'll find what you were looking for!
jaapv Posted September 16, 2014 Share #122 Posted September 16, 2014 I've said it before- DOF is in the eye of the beholder. Link to post Share on other sites More sharing options...
lct Posted September 16, 2014 Share #123 Posted September 16, 2014 This is false, and we should be discussing the validity of the simplistic CoC concept altogether. Given an APO and a non-APO lens, such as the 75 Summilux and Summicron, the average CoC for all the frequencies of the visible spectrum near the "intended focus point" will be smaller for the APO lens... No wonder why you find differences if you apply different CoC values to lenses you compare. Problem is they are not visible in the pics as expected. Contrast, color rendition and bokeh are indeed different but DoF looks remarkably similar in spite of a slight difference in focal length, as expected again. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/233759-75mm-apo-depth-of-field/?do=findComment&comment=2671539'>More sharing options...
pico Posted September 16, 2014 Share #124 Posted September 16, 2014 No wonder why you find differences if you apply different CoC values to lenses you compare. Problem is they are not visible in the pics . Forgive me if I am obtuse, but what can we observe on a monitor? Link to post Share on other sites More sharing options...
lct Posted September 16, 2014 Share #125 Posted September 16, 2014 Forgive me if I am obtuse, but what can we observe on a monitor? At 100% magnification, more than one can see when looking at a print at 25cm viewing distance, which was a criterion for the standard CoC value of 0.03mm if i remember well. Link to post Share on other sites More sharing options...
pico Posted September 16, 2014 Share #126 Posted September 16, 2014 At 100% magnification, more than one can see when looking at a print at 25cm viewing distance, which was a criterion for the standard CoC value of 0.03mm if i remember well. Then don't do that. Link to post Share on other sites More sharing options...
lct Posted September 16, 2014 Share #127 Posted September 16, 2014 Advertisement (gone after registration) Why not but but we will see even less difference when comparing DoFs then... Link to post Share on other sites More sharing options...
CheshireCat Posted September 16, 2014 Share #128 Posted September 16, 2014 No wonder why you find differences if you apply different CoC values to lenses you compare. Problem is they are not visible in the pics as expected. Contrast, color rendition and bokeh are indeed different but DoF looks remarkably similar in spite of a slight difference in focal length, as expected again. The magenta/green "halos" you see is what I'm talking about. Any person with good eyesight can see these issues even on a postcard sized print, and will be bothered. Now, it all boils down to your definition of "depth of field", but my pragmatic definition is that magenta crap is not what I want to see in a photo. Link to post Share on other sites More sharing options...
lct Posted September 16, 2014 Share #129 Posted September 16, 2014 DoF is a distance, nothing else. Link to post Share on other sites More sharing options...
CheshireCat Posted September 16, 2014 Share #130 Posted September 16, 2014 DoF is a distance, nothing else. Interesting how an amazingly complex human perception can be reduced to such a trivial concept of distance. Link to post Share on other sites More sharing options...
lct Posted September 16, 2014 Share #131 Posted September 16, 2014 DoF is DoF what else can i say? I won't teach you what you can read on Wikipedia or elsewhere and i was a teacher in law, not in physics i'm afraid so my incompetence level has reached a non-return point anyway . Link to post Share on other sites More sharing options...
CheshireCat Posted September 17, 2014 Share #132 Posted September 17, 2014 DoF is DoF what else can i say? I won't teach you what you can read on Wikipedia or elsewhere and i was a teacher in law, not in physics i'm afraid so my incompetence level has reached a non-return point anyway . Fair enough The most important thing I have learned in my life is never trust *pedias. I always experience things on my own if I really want to learn something. ... even if I may be wrong 1 million times Link to post Share on other sites More sharing options...
John Black Posted September 17, 2014 Share #133 Posted September 17, 2014 Thanks. So why this "Version II" thing ? Version II denotes the sliding hood. This is MY naming, not Leica's. All Leica encoded in the DNG prior 2.0.1.5 was 75/1.4. No words. Lightroom added the lens name as part of their decoding process. I use C1, so the missing lens name was super annoying when trying search on "75mm Summilux" and pulling up shots from the M8, M9 and M-240. To "fix" this, I use EXIF Changer and add my own lens names and serial numbers. With 2.0.1.5 Leica is now putting the lens names into the EXIF, but I still use EXIF Changer to fill data like Max Aperture and more complete lens names. Link to post Share on other sites More sharing options...
IkarusJohn Posted September 17, 2014 Share #134 Posted September 17, 2014 Fair enough The most important thing I have learned in my life is never trust *pedias. I always experience things on my own if I really want to learn something. ... even if I may be wrong 1 million times Let us know when you've worked out Newton from scratch. I doubt you'll get as far as Rutherford or Einstein ... Link to post Share on other sites More sharing options...
CheshireCat Posted September 17, 2014 Share #135 Posted September 17, 2014 Let us know when you've worked out Newton from scratch. I doubt you'll get as far as Rutherford or Einstein ... Just let me know when I am wrong. That will do Link to post Share on other sites More sharing options...
pop Posted September 17, 2014 Share #136 Posted September 17, 2014 Interesting how an amazingly complex human perception can be reduced to such a trivial concept of distance. DOF is not a measure of an amazingly complex human perception, much as BMI is not a measure of an amazingly complex set of bodily functions. DOF has quite a simple definition and quite a simple (if mostly obsolete) purpose. If you think one or both useless, why take part in a discussion about the DOF of some specifically named lenses? Why don't you start another thread on "amazingly complex human visual perception of sharpness in photographic pictures as rendered on computer LCD screens", if that is what interests you? This is the thread about DOF. We all know (or could know) the definition of DOF. Stop complaining about the topic, please. Link to post Share on other sites More sharing options...
lct Posted September 17, 2014 Share #137 Posted September 17, 2014 I would not say that the purpose of DoF is obsolete personally. It's just that pixel peeping on monitors allows us to see more details that when looking at prints at a standard viewing distance like we did and still do with film. But we can perfectly use smaller CoC values to take this new way of viewing into account if need be. This would not change anything when comparing the DoF of different lenses though, aside from the necessity of using DoF markings of lenses differently, and this would complicate other matters also, namely the measure of the critical base length of rangefinders, but it is another story. Link to post Share on other sites More sharing options...
pgk Posted September 17, 2014 Share #138 Posted September 17, 2014 DOF has quite a simple definition and quite a simple (if mostly obsolete) purpose. This is the thread about DOF. We all know (or could know) the definition of DOF. Actually, if you think about it, this thread is about the difference between calculated and observed depth of field (see the OP) and why the two differ. If someone was to actually use the 'standard' DoF calculations to work out the simple expected 'zone of sharpness' in purely distance terms, and then actually map this (difficult and time consuming and would require considerable 'judgement') then I expect many would be surprised at the inconsistencies (and no, I'm not going to volunteer) and rather odd shape of the ensueing three dimensional area. Some of us have observed these inconsistencies and accept the DoF calculations and scales as mere guidance. Others still appear to stick rigidly to the calculated values/scales which were obsolete long before digital, and were a yardstick designed for conditions acceptable long ago. As ever the debate will no doubt rumble on, but at least its aired the topic and may have provided insights into how people deal with specifics quite differently. Link to post Share on other sites More sharing options...
lct Posted September 17, 2014 Share #139 Posted September 17, 2014 There is no rigidity in DoF formulas. They allow us to choose whatever CoC value we prefer. Here's what could give a 0.02mm CoC compared to the standard 0.03mm. 3 centimeters difference more or less. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/233759-75mm-apo-depth-of-field/?do=findComment&comment=2671826'>More sharing options...
jankap Posted September 17, 2014 Share #140 Posted September 17, 2014 The only DOF we see and read as meters are the engravings on the lens. As 01af writes there are several focal lengths for one lens sample. The nominal is the rough focal length of the group, for instance to switch the viewfinder (50, 75, 90mm) The designed one is the optimized result of the development (perhaps 52.5mm). The actual would be the focal length of a real sample of the actual production lot (for example 51.8mm), but still within the required tolerances. It is possible, that engravings on the lens even follow the designed focal length. So, not all lenses equally engraved. It is not very probable, that the real focal length is engraved. The engravings should not be taken too serious, because the readings are very vague. One could interpret at f/16 both on the Lux 75 and the Cron75: the distance 9 meters, I think. Jan Link to post Share on other sites More sharing options...
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