Rick Posted March 31, 2015 Share #241 Posted March 31, 2015 Advertisement (gone after registration) Point taken on OP. Agree. My problem is that when I look at some images I find 'fringing' variability across the frame, in intensity, spread and so on. As far as I can see, sometimes its clearly a mix of problems. Sometimes it is mixed, like OOF-CA + sensor blooming. Sometimes it is just OOF-CA that is variable due to the lighting and it becomes difficult to parse out from an optics understanding. Give me a specific example posted here, please. What I still can't get my head around is the incoherent variability which seems to have no correlation with any common factor. I can correct most and often all of it, but the settings are varied too. And sometimes its simply not correctable. I agree. Sometimes the lighting variables combined with the plane of focus combined with the color of the fringing is difficult for the simple sliders in LR to handle. But, it doesn't mean that we can't explain the optics of the specific image. And, nobody has correctly explained the purple fringing that is brighter against a bright background like sky and then is adjacently gone when a branch has a dark background behind it. So, some decide that it must therefore be something else, like the sensor. But, it is still OOF-CA. It just needs to be explained by the optics of the OOF-CA and it can be easily done so. I'm sure it seems like something else is going on if you don't have the optics of the situation revealed to you or you don't understand exactly what is going on with the optics of the lens... but the effect of OOF-LA no matter how complex it appears, is not the sensor. I wonder if on occasion there are other localised impacts (such as reflections within micro-lenses or the sensor cover glass due to very high light intensity in some areas) which add in to cause yet more variability? Yes, I agree that there exist many occasions where there are sensor effects like blooming, and there is flare, etc. My only real point is that the OOF-CA images shown here can ALL be explained by the lens optics. Blaming the sensor or other unknown factors at work is just not understanding the optics. I struggle here to not sound like CC. But, it is just obvious to me. And, like CC I just need specific questions about the images that bother you and I bet I can explain them. I also believe we are not that far off from each other here. Rick Link to post Share on other sites More sharing options...
Advertisement Posted March 31, 2015 Posted March 31, 2015 Hi Rick, Take a look here Is this CA problem on my 50/1.4 ASPH, it's normal or not?. I'm sure you'll find what you were looking for!
algrove Posted March 31, 2015 Share #242 Posted March 31, 2015 Maybe we should use a Monochrom camera only. Link to post Share on other sites More sharing options...
Rick Posted March 31, 2015 Share #243 Posted March 31, 2015 Maybe we should use a Monochrom camera only. Hi Lou. Monochrome isn't imune to OOF-CA either. And, the LR sliders don't work with the M. Luckily, it isn't anywhere as noticeable with the M. Rick Link to post Share on other sites More sharing options...
pop Posted March 31, 2015 Share #244 Posted March 31, 2015 Hi Lou. Monochrome isn't imune to OOF-CA either. And, the LR sliders don't work with the M. Luckily, it isn't anywhere as noticeable with the M. Rick How about a purple Monochrome? Link to post Share on other sites More sharing options...
thighslapper Posted March 31, 2015 Share #245 Posted March 31, 2015 I also believe we are not that far off from each other here. Rick aaah Rick .... if only it were so simple.... this discussion is polarised into the : 1.Purple fringing is always Chromatic Aberration and always arises solely from the lens 2. Purple fringing is due to Chromatic Aberration but sometimes other factors other than lens issues are involved. We are basically at a Mexican Stand-off ..... neither side is going to back down so I suppose the sensible thing is to politely acknowledge each others opinions and leave it at that for now....... We had the same business with the Italian Flag Syndrome. My suggestion of the cause was actually very close to the one Leica finally came up with ......... Link to post Share on other sites More sharing options...
CheshireCat Posted March 31, 2015 Share #246 Posted March 31, 2015 Adobe from 2012 they report 3 types of chromatic artifacts. Lateral CA. LoCA. And, Sensor Bloom. I think Adobe SW engineers were also deceived by the "Sensor Bloom" myth. The average SW engineer knows about CCD and CMOS sensors as much as the average cook or housewife . Link to post Share on other sites More sharing options...
CheshireCat Posted March 31, 2015 Share #247 Posted March 31, 2015 Advertisement (gone after registration) OOF CA is not a classical aberration because it is always zero in the focal plane. Depends on the definition of OOF CA. The physics behind OOF CA and LoCA are the same. The only thing that's different is the "sampling point". For LoCA, the sampling point is "the focus plane"; but if you think about it, because of LoCA, there is no such thing as "the focus plane". I only call it OOF CA because it makes Andy happier Link to post Share on other sites More sharing options...
CheshireCat Posted March 31, 2015 Share #248 Posted March 31, 2015 We are basically at a Mexican Stand-off ..... neither side is going to back down The problem here is that one side has shown examples, references, and provided solid explanations, while the other side is just criticizing and talking about gut feelings. Link to post Share on other sites More sharing options...
Rick Posted March 31, 2015 Share #249 Posted March 31, 2015 Depends on the definition of OOF CA.The physics behind OOF CA and LoCA are the same. The only thing that's different is the "sampling point". We agree. For LoCA, the sampling point is "the focus plane"; but if you think about it, because of LoCA, there is no such thing as "the focus plane".I only call it OOF CA because it makes Andy happier We agree. So, I'll call it OOF-CA Rick Link to post Share on other sites More sharing options...
Rick Posted March 31, 2015 Share #250 Posted March 31, 2015 CC. In the shot of the window, it is so interesting. You can look into the deepest magenta and see a red line at the outside and blue line on the inside and magenta in between. It is really interesting to see the effect of the optical design of correcting F and C color (blue and red) by the lens designer. Both colors end up pretty much at the same point even though they are at opposite ends of the visible spectrum. In other words, they both shouldn't even be hanging out in the same neighbor hood if this was a primary spectral effect from lateral chromatic aberration. But, because they are produced as an effect of the achromatic correction and result from the secondary spectrum... they are next to each other and in the right order. Too cool. Rick Link to post Share on other sites More sharing options...
lct Posted March 31, 2015 Share #251 Posted March 31, 2015 Pretty impressive to be surrounded by world class experts calling "BS" the works of a Cambridge university site and "myth" the knowledge of a company like Adobe. One feels really tiny... Link to post Share on other sites More sharing options...
Rick Posted April 1, 2015 Share #252 Posted April 1, 2015 Pretty impressive to be surrounded by world class experts calling "BS" the works of a Cambridge university site and "myth" the knowledge of a company like Adobe. One feels really tiny... Hi LCT, I was just looking through my old optics notes of three years of post graduate optics and re-familiarizing myself with the subject as I read through this thread. This stuff is a pretty heady bit of semi-advanced optics. We designed achromatic doublet lenses using formulas and then went on and made apochromatic three element lenses and the math was more complex. Next, we corrected the resulting lateral spherical aberrations and coma. By this time we were back to ray tracing. I suppose now, computers are used for this last part. For the first part the power and some definable variables are used. So, it can be done with formulas. By the time you get to correcting for the resulting spectrums, which are a byproduct of the doublets, colors are inverted in the order of the spectrum. Now, lens shape and and other more complex characteristics come in to play and it goes back to ray tracing. I'm really not trying to convince you I'm an expert, just saying this stuff quickly gets complex even for Adobe programers. Anyway, this has all been very interesting for me and I enjoyed the posts here. I looked up some of the stuff in my notes and a couple of things on the inter web and I have to say there is some real laughable stuff out there. For the most part I hate to say that I believe CC is right. He is a little pedantic but, he is just trying to make a point that we have to be careful how we describe everything and what terminology is used or it gets mucked up. Also, I agree with him that it would be nice if people could at least ask specific questions about what they don't understand rather than just saying that we are going to have to agree to disagree. There are some really good examples here. Some of the effects you see haven't even been addressed or explained Rick Link to post Share on other sites More sharing options...
lct Posted April 1, 2015 Share #253 Posted April 1, 2015 [...] I'm really not trying to convince you I'm an expert, just saying this stuff quickly gets complex even for Adobe programers. [...] You are far more an expert than i in this area anyway. How could you explain cyan/blue fringing like this one, if any? Just curious. 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/242349-is-this-ca-problem-on-my-5014-asph-its-normal-or-not/?do=findComment&comment=2790692'>More sharing options...
Rick Posted April 1, 2015 Share #254 Posted April 1, 2015 Can I just ignore the part where you snidely call me an expert and take the razing in good fun? All I see here is what we seem to have agreed to term, OOF-CA. I see purple in the front and green fringing behind the point of focus. Which I am sure you see. Now, what specifically is it that you believe is unique or different about this example. I mean, what are you looking at that isn't explained by LoCA? I honestly don't understand what you don't get? Rick Link to post Share on other sites More sharing options...
lct Posted April 1, 2015 Share #255 Posted April 1, 2015 [...] I see purple in the front and green fringing behind the point of focus. Which I am sure you see. [...] Even when pushing red and magenta saturation by 100% (pic) i can't seem to see that but i'm on a laptop here so perhaps i'm missing something... 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/242349-is-this-ca-problem-on-my-5014-asph-its-normal-or-not/?do=findComment&comment=2790703'>More sharing options...
Rick Posted April 1, 2015 Share #256 Posted April 1, 2015 Your picture is pretty difficult to look because of the low size. But, you can see the magenta(you call purple)? And, it is hard to see, but am I seeing green color in the very far tree that is bare? Anyway, the magenta is certainly in front of the point you focused on. That is LoCA. Rick Link to post Share on other sites More sharing options...
Rick Posted April 1, 2015 Share #257 Posted April 1, 2015 Also, I'm not sure why you are pushing red and magenta 100%... why are you doing this? Link to post Share on other sites More sharing options...
lct Posted April 1, 2015 Share #258 Posted April 1, 2015 To check if there is some significant red and/or magenta fringing in the pic. Just trying to gather facts for my own edification. Link to post Share on other sites More sharing options...
pgk Posted April 1, 2015 Share #259 Posted April 1, 2015 Also, I agree with him that it would be nice if people could at least ask specific questions about what they don't understand rather than just saying that we are going to have to agree to disagree. Rick Whilst your explanations make good sense in some ways, you cannot ignore the sensor/software issues which convert the image thrown onto the sensor into the image file we have to deal with. At high intensity light levels, the information becomes non-linear and depending on its intensity, blooming, whatever, will be increasingly spurious. Even when there is underlying CA there will be additional distortions and sometimes even when there is no CA there will still be distortions in the data. So, whilst you may be dealing with CA (or sometimes not) there are other elements causing problems in images. You say yourself "nobody has correctly explained the purple fringing that is brighter against a bright background like sky and then is adjacently gone when a branch has a dark background behind it. So, some decide that it must therefore be something else, like the sensor. But, it is still OOF-CA. It just needs to be explained by the optics of the OOF-CA and it can be easily done so.", and go on to say "Yes, I agree that there exist many occasions where there are sensor effects like blooming, and there is flare, etc.". Where we still disagree is that I see a more complex picture than that formed purely by optics (no pun intended;)), although I have to say that often the components of the image that I find problematic are subtle and would be both difficult and time consuming to adequately post on a forum such as this (I'd have to show before and after post processing and explain all the adjustments made and so on - 'though I might try as I come across images which display such problems). I am happy to accept that some fringing is CA, but I'm still far from convinced that all fringing is as a result of CA or, in some cases, even has any component of CA. CA as far as I am concerned, is a culprit but not the only one and sometimes it neither occurs nor cause problems where I would expect it to. [And just in case you think that this is all being rather pedantic, I do have at least one (scientific) application where high contrast edging can cause problems when looking at some 'irridescent' colour markings on small fish which reflects so strongly that it is difficult to maintain highlight detail in them....] Link to post Share on other sites More sharing options...
indergaard Posted April 1, 2015 Share #260 Posted April 1, 2015 To the OP: Yes, this phenomenon is normal on the 50mm Summilux ASPH, and to a lesser degree on the 35mm Summilux FLE, and to a much bigger degree on the 50mm Noctilux ASPH ... On the M240 and M9 in my experience. Link to post Share on other sites More sharing options...
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