very bad purple fringing with 50D how about 7D?

Discussion in 'Canon EOS' started by douwe_spoelstra, Nov 21, 2009.

  1. Okay, some of you might be aware, but the 50D has a serious problem! I would like to pop a question to all you happy 7D owners. The question concerns non repearable purple fringing from 50D. I do waterports photography and found the 50D to be absolute rubbish in this case. In very backlit situations the 50D would color the water in the picture entirely purple. You do not believe? well I will post a picture to proof what I am saying. In fact 15% of all my watersport photographs are distroyed by this phenomenon. I have never seen this problem with the previously owned 20D! And so in complete dispair I have sold the 50D and bought one of the last remaining 40D's and guess what.... everything is back to perfect again. So this step up in 50% more pixels has some serious downsides, if you ask me. So you can guess my question, does the 7D display the same problem? I Really would like to buy that camera but offcourse only if its usefull. And oh yes, if I look at the 50D pictures and compare them to my 40D pictures, I find the 50D so soft that I do not see any gain in I Q in the real world over my 40D's. Maybe I am crazy but printed big size the 40D looks sharper, huhh how is that possible. And so for me the 5D markii is back in the picture.. here you can see an example, I know its not art but you'll see what I mean http://www.photo.net/photodb/member-photos?user_id=5738984
    00V4BW-193027584.jpg
     
  2. Try hue/saturation > magentas > saturation -100
    I would buy a camera with great care and consideration, they will usually stay with you a long time. If there isn't anything 'major' you 'need' just be happy with what you have. Regarding print sizes... well, I sore a fantastic print from a 5MP camera earlier in the week, in a gallery. It must have been atleast A3 size.
    Take care, Richard
     
  3. Hard to see with this little information what is going on. The area in question is the brightest in the image. Are your highlights blown? Lots of things other than the camera body can contribute to purple fringing. I have been shooting with a 50D for 6 months and haven't had any substantial problem with purple fringing. then again, off the top of my head, my water shots have been in brighter light.
     
  4. Were you using the same lens in all pictures? This is usually a lens issue. But I suppose cramming too many pixels too close together could have a price.
    Do you use a polarizer? For the type of shooting you do I would always carry one to control the extreme highlights which is what causes CAs in the first place.
     
  5. This is essentially an exposure problem, and it does not affect only your camera. The backlit water is extremely bright, and the brightest portions are small spots of light reflected directly from the sun. Unless you drop the exposure level so that these sources don't blow out you will get this effect. Of course, this creates another problem if you are trying to retain any detail in the shadowed areas of your intensely backlit subject.
    You can often reduce (or sometimes eliminate) this in post using a variety of techniques. The recovery slider in ACR (or similar in other RAW converters) can sometimes recover some of the blown highlights. In ACR you can also use the defringe setting diminish this. The tools for adjusting CA can also help.
    Once you are in Photoshop in may be possible to do some work with masks and selections and saturation to help out. Finally, do check to see if the effect is really visible in the final print - not everything visible at 100% on the screen will have an effect on the final result.
    None of this is to say that this isn't an issue, but I find that it is not a factor with one particular camera.
    Dan
     
  6. Purple fringing is a lens problem. What lens are you using?
     
  7. "Purple fringing" is not purely a lens problem. It can happen with some very fine lenses in challenging exposure situations, particularly when very bright (e.g. - blown out) areas or highlights are juxtaposed with darker areas.
    Dan
     
  8. That's easy to fix
    00V4Gu-193087584.jpg
     
  9. I've never seen purple fringing from my 50D. I've shot a lot of strongly backlit subjects with my 7D and even the blown HLs aren't purple.
     
  10. What lens were you using? I've seen this effect with cheaper lenses, but never with L's.
     
  11. The 35L and 85L will produce purple fringing under certain conditions.
     
  12. Len,
    They are two of the very few Canon L lenses that do not have Flourite elements, that is they are not Apochromatic and corrected for three different light wavelengths.
    Nice observation, Scott.
     
  13. Another look with magenta desaturation.
    00V4JG-193107684.jpg
     
  14. Lenses may cause purple fringing but camera bodies and sensors do not. I just checked several water and backlit images from my 50D and there is no purple fringing at all, nada, zip, none.
    My 40D does not have purple fringing when shooting backlit subjects either.
     
  15. I don't think most people here understand your question, Douwe. You have discovered a clear difference between cameras. This has nothing to do with how to repair the photos. I think you are asking whether 7D owners have experienced this anomaly. In my experience, some lenses work better with some cameras, so it might be helpful (or confusing) to identify which lens you are using.
     
  16. This guy claims he sold his 50d and bought the 40 so why is he whinning about the 50d now. I smell troll here. He posts one crappy picture and were all supposed to beiieve he's on the level yeah right
     
  17. Wikipedia, for what it is worth, claims the sensor may be part of the problem in purple fringing. http://en.wikipedia.org/wiki/Chromatic_aberration#Photography and http://en.wikipedia.org/wiki/Purple_fringing .
    That fits my experience with Nikon cameras. I had it quite a lot with a D40X but hardly ever with a D300 using exactly the same lens.
    With a Canon 20D and a 135mm f/2.0 Canon lens I managed to get chromatic aberration with two colours at the same time. I assume newer Canon cameras would not have that problem. See samples here: http://photophindings.blogspot.com/2009/04/chromatic-aberration.html
     
  18. I took this yesterday, I was testing out a 5dMK2 and a 7d, I know it's not water but it's the best high contrast shot I could get in a shop. They are 100% crops both shot at 160th,5.6,iso 640, on a canon 24-70 2.8 L.
    http://www.photo.net/photodb/folder?folder_id=942184
     
  19. Lets stick to the question, I posted a question wich was, does the 7D have the same problem as the 50D?
    Offcourse they are blown highlights, but believe me or not the lenses I use are the same (canon L) I allways use The 20D and the 40D clearly do not! have this problem... Offcourse you can repair it in p.s., I have succeeded doing just that. But that is not what you want is it? In the mean time I found this review and what do you know... his findings are the same as mine http://www.luminous-landscape.com/reviews/cameras/50d.shtml
    And thank you people that take this question serious, well appreciated, I am not trying to put anybody's camera down, I am just looking for an answer.
     
  20. The OP has a legitimate question. My D80 has CA problems, though not as bad. Using the same lens on a D300 almost eliminates the problem. Of course the D300 has built in CA correction, which manages to make shots useable, which with the D80 were not salvageable even using CA corrections in CS2. It is largely a lens issue, but the camera can make a huge difference in my case.
     
  21. Here is the answer to your question. No canon cameras do not have purple finging problems. and yes you do have issues. you have been bashing this brand for almost a year now under various names. Get a life
     
  22. Try hue/saturation > magentas > saturation -100​
    I would strongly advise against this approach. The saturation adjustment in Photoshop should never be used on a narrow hue range with that much strength, as there is no blending or fall off, but rather a completely abrupt, harsh transition. If these are the only magenta tones in the entire image, the effect will be less destructive, but in general this type of saturation adjustment is almost always quite destructive and is usually a very bad idea.
     
  23. Douwe,
    Your point was "The question concerns non repearable (sic) purple fringing from 50D". You have not shown an image that has that so there is not an issue as far as I can see.
    I was on topic, I took your point seriously and, from the image you posted, you do not have a problem. Does anybody want to do PP to every shot? Not really, but are we prepared to work on worthwhile images, and, how many of them require no post? None of mine that is for sure, and I come from a slide background.
    The main thing I get from these threads is that there seems to be a huge difference in peoples cameras and the quality of the images they get out of them, all across the camera models. Some people swear there is a major issue and others just can't replicate it. I recently did tests on my camera to see if it has an issue that a knowledgeable pro who uses the same model says his body exhibits, mine does not. There seems to be a huge variance in how well people take the images that exhibit problems but even when you level the playing field with abilities or methodology different bodies of the same model show different results.
    It seems to me some people just don't know what they are doing and there are just as many quality control issues at Canon. It seems as simple as that, just don't ask me to work out what to do about it! Very careful examination and hands on testing with money back warranties seems the only way to get a good body, secondhand or new. Sending things back to Canon seems a pointless waste of time half the time, it seems the body is almost mostly within spec. Very very frustrating if you get a bad one.
     
  24. Magnus,
    If you look hard enough you should see two coloured chromatic aberration on any image, particularly the corners, especially if the lens is not apochromatically corrected.
    That is one of the areas where digital really kills itself, because we can all zoom into 100% we do, we never printed the majority of our images anywhere near that size so didn't notice how "bad" our lenses are. They are the same lenses though.
     
  25. Brett - I'ved used that as a 'quick fix' for numerous photos in the past, usually when there is a little CA at the corners and I can't be bothered to go back through ACR to adjust. No problems here. I print fairly big too, although I'm never one to pixel peep. Although I'm always one to find a solution, rather than whinge to strangers over the internet ;)
     
  26. Scott,
    Some? Yes. Much? No.
    Mag
     
  27. I cannot answer the 50D v. 7D question. But I can tell you that the problem occurs on all Canon cropped sensor and full frame DSLRs that I have used in extreme exposure situations like the one you have shown, and that the solutions include the steps I mentioned in my earlier post.
    I cannot rule out the possibility that the 7D is somehow "worse" than other cropped sensor bodies like the 50D since I have not used either of those specific cameras. I can speculate that a) this is a type of artifact that is common to DSLRs due to the way they deal with over exposure, b) that to the extent that it is a sensor related issue it may appear to be "larger" in 100% crops on the 7D due to the denser photosite placement - which suggests that you are both looking "more closely" than you would be with a 50D 100% crop and that the closer spacing might make "spill" of light more of an issue.
    As I wrote... speculation.
    Dan
     
  28. G Dan,
    This shot, taken just for this thread, doesn't exhibit the kind of magenta fringing that Douwe is worried about so it is not really accurate to say "I can tell you that the problem occurs on all Canon cropped sensor and full frame DSLRs that I have used in extreme exposure situations like the one you have shown" as this one clearly does not.
    It is a seascape very similar in lighting to Douwe's original and I deliberately overexposed by one stop to exaggerate the blown water. Full image to left, 100% crop of water highlights to right, obviously all untouched in post other than crop and convert to jpeg as the original was shot in RAW.
    00V6XZ-194671584.jpg
     
  29. And so for me the 5D markii is back in the picture..
    I have found that the "purple fringing" phenomenon can also be generated with shots taken with a 5D2 - however there seems to be more to this than meets the eye. I remembered a couple of shots I had taken that showed this effect, your post prompted me to go back and investigate further. In the first attached Bridge screen shot you can clearly see two purple tinted shots and two normal looking shots. The purple ones were not purple until I reduced the exposure 1 stop in ACR! Now, if I re-open up the selected purple shot in CS4 raw converter it still looks purple, but just zoom in to 100% and the purple fringing almost disappears, screen shot 2. Convert the purple looking shot to jpg without making any adjustments and you get a shot devoid of purple fringing. Go figure.
    I've no explanation for what is going on here, but it seems the problem can be both generated and solved in PP! Scott, try reducing the exposure in ACR of your over exposed shot, my guess is that you will then see the the "purple fringing". I wonder if this is just a Canon sensor phenomenon?
     
  30. And so for me the 5D markii is back in the picture..
    I have found that the "purple fringing" phenomenon can also be generated with shots taken with a 5D2 - however there seems to be more to this than meets the eye. I remembered a couple of shots I had taken that showed this effect, your post prompted me to go back and investigate further. In the first attached Bridge screen shot you can clearly see two purple tinted shots and two normal looking shots. The purple ones were not purple until I reduced the exposure 1 stop in ACR! Now, if I re-open up the selected purple shot in CS4 raw converter it still looks purple, but just zoom in to 100% and the purple fringing almost disappears, screen shot 2. Convert the purple looking shot to jpg without making any adjustments and you get a shot almost devoid of purple fringing. Go figure.
    I've no explanation for what is going on here, but it seems the problem can be both generated and solved in PP! Scott, try reducing the exposure in ACR of your over exposed shot, my guess is that you will then see the the "purple fringing". I wonder if this is just a Canon sensor phenomenon?
    00V6eo-194735684.jpg
     
  31. Screen shot 2
    00V6er-194735884.jpg
     
  32. and the jpg of same purple fringed pic without any further adjustments...
    00V6ex-194737584.jpg
     
  33. Scott, interesting example, and it certainly doesn't exhibit the fringing/blooming nor does it exhibit any CA. I'm impressed.
    One thing to keep in mind about many of my posts - I often (but not always) choose my words somewhat carefully to be a bit less than absolute. For example:
    "I can tell you that the problem occurs on all Canon cropped sensor and full frame DSLRs that I have used in extreme exposure situations like the one you have shown"
    I didn't write that, for example, "the problem [always] occurs." And your shot is apparently proof of that and an illustration of my wording was correct.
    The "problem" (though I think of that word as suggesting "an issue to deal with" rather than "a way Canon falls short") certainly is something that I find myself having to deal with on DSLRs ranging from an 8MP cropped sensor body to a current 21MP FF body. There are two ways (perhaps three?) that the "problem" can occur:
    • CA "adding color" to scenes containing essentially randomized, highly detailed subjects with many edges between pure white and darker tones - like sparkling, sunlit water. This can often be improved in post by defringing and/or using the CA (red/green and yellow/blue) adjustments.
    • Purple fringing ("sensor blooming?") adding purple edges to the dark portions of boundary areas between very bright (typically blown out) and darker areas. The classic is branches against the sky. Fixing this in post is more complicated. Sometimes exposure decisions can help here.
    Several things can make this (the reflections on water) situation especially complex. Lens quality can come into play to the extent that CA adds color to otherwise nearly colorless areas. And a fringing can do this even with lenses that have low levels of CA.
    I agree that it is possible to come up with shots that don't exhibit this. After seeing your example I went back through some of my older RAW files that include very similar subjects - brightly backlit reflections on water. I was going to do this to show examples of the "problem" on several bodies I've used. And I did find them. But I also found some examples that don't exhibit the problem and others in which it was completely resolved by some simple post processing steps.
    Dan
     
  34. I had severe purple fringing problems with a Ricoh I owned, and poster W. Bray is right on the money suggesting that is caused by excessive pixel density. Stepping "down" to a camera with less pixels (a 40d) was the fix. Less is sometimes more I guess.
    Jerry W
     
  35. I had severe purple fringing problems with a Ricoh I owned, and poster W. Bray is right on the money suggesting that is caused by excessive pixel density. Stepping "down" to a camera with less pixels (a 40d) was the fix. Less is sometimes more I guess.
    Jerry W
     
  36. If the fringing is seen more on the higher photosite density sensor, there are a couple things to consider:
    1. It may seem more pronounced when you view the image at 100% magnification because you are effectively looking "more closely" at the image. A 100 x 100 pixel 100% crop from a 18MP sensor comprises a much smaller portion of the overall image than a 100 x 100 pixel 100% crop from a 8MP sensor. (In film terms, this would be sort of like inspecting one sample with a 10x loupe and then looking at the next sample with a 15 x loupe.)
    2. Related to this, the flaw that is more obvious from the 18MP sample at 100% than from the 8MP sample at the same magnification may well affect a print image of a given size the same amount. A one pixel wide "flaw" in the 18MP image will be smaller in a print than a 1 pixel wide flaw from the 8MP image if printed at the same size.
    It is tricky to do direct comparisons between different photosite density samples (and between different format samples) at 100% on the screen. While it seems like looking at the samples at 100% would reveal the most "truth" about the images, it is also very misleading in several ways.
    Now, none of this is meant to prove that there isn't a problem - I can't really do the objective comparison myself, and such a careful comparison might reveal an actual issue. But it is a caution about assuming too much from a sample.
    Dan
    (My idea of the best - but still not perfect - test would be to take two samples through similar ideal workflows to prints at the same size and then compare.)
     
  37. Have you tried using a UV filter?
     
  38. I would have thought that by now someone would have taken their 7D out and tried to replicate the OP's situation. We're getting into silly-land with answers. I'll try to get out some afternoon this week to see if I can replicate the situation with my 7D.
    Dave
     
  39. Rick,
    You are 100% correct. I'll try to post some examples later. If you take my shot and open in ACR and then reduce exposure by 1 stop it has a magenta fringe on screen at screen size (fit to screen) if you zoom in to 100% the fringe goes. If you print the file there is no fringing any which way.
    This seems very strange to me.
    I would like to know how many of Douwe's images have issues prior to development.
    It seems that some images, mine and Rick's at least, can be made to exhibit magenta fringing even when the native capture does not, it is a post processing issue not a Canon issue, and I can't make the issue actually affect a print. My images are not shot with a particularly high density pixel sensor and on a full frame. It does not appear to be density or sensor size related but a pp screen rendering issue.
    I have not had the time to do the same thing in DPP only ACR. I have several shots in the sequence above of different exposures, I'll do some more post on them and see what happens.
     
  40. This is really sad. I am a professional photographer and shoot with my Cannon 50d a ton! I love that camera! However I have lots of problems shooting on bright sunny days with pictures showing lots of purple fringe. I came onto this site to find answers and what I hear is a ton of accusations. It could be the lenses, I have sigma and promaster lenses for the 50d just because Im in the woods with that camera a ton and dont want my exspensive L lenses damaged. I havent taken my 7d or 1d mark 3 outdoors just because Im rough on my outdoor cameras. But Im going to take the 7d out soon so I can compare the purple fringe phenom. For those who thinks this guy is bashing Cannon, he didnt say hey go buy Nikon or Sony he said he traded down to get better photo's. For those who think he is making it up there are lots and lots of people asking about the same problem. I know with my studio cameras I can adjust all of the lighting in the camera so that I dont have o worry about it. But Im inside I dont in there anyway. I would imagine that there is a way to do it with the 50d also, I just dont know how yet. Any how I will shoot with both soon and send in the results. I know this whole thread was done months ago but Im sure people still want to know.
     
  41. The Magenta problem with the 50D is real. I have two 50D's, two 40D's, and a 1D Mark III. The Magenta problem is only visible with the 50 D. I tried the Canon Firmware update, and it's still there. I've tried combinations of Picture Styles, with custom settings, and it's still there. I've tried WB Shifts, and it's still there. I tried Arthur Morris suggestion regarding settings, and it's still there. I don't want advice regarding how to fix this in Photoshop. I want to fix it "in camera". I photograph wildlife, and use Canon EF L telephoto lenses....they are not the problem. Any advice including in camera adjustments that have worked for any of the members would be appreciated. I am not making this up, and have been fighting this problem for a long time. I just want to be as satisfied with my 50D's, as I am my other Canons. Thank you. Chris Webb (I listed my original Canon FD to EOS Converter Adapter for sale today...please look if you're interested).
     
  42. Chris,
    Did you do any exposure adjustments to your images prior to seeing the magenta issues? Can you post an example. If you read my earlier answer then you can see that my 1D files can be made to do it, but only on screen after exposure adjustments. Do they print magenta?
     
  43. I got some really bad purple fringe taking a backlit shot with my 7D and 50mm lens (ISO400, f 1.6, 1/80sec)....I am working in Lightrooom, definging made not difference, decreasing the purple saturation and increasing highlight toms and light tones were the only way to get rid of it....although I lost the edge definition.....
    00ZGZL-394551584.jpg
     
  44. Karen, did you zoom in to 100% to confirm the fringing is not a software issue first? Can you post your image pre processing?
     
  45. Yes, I zoomed in (in Lightroom), and it's there!...this is pre-processing, the image was taken in RAW and I just exported it as JPEG in Lightroom....I will try in another program?
    I have more photos where I used a little off camera flash with the same settings and the purple is completely gone (the blinds are much more visible), also some where I increased to ISO500 and 1/125 and although there is a little purple, the effect is not nearly as bad....
     
  46. Karen,
    You have a completely different issue, the light through the window is way way too bright, the dynamic range is vastly outside the capabilities of the sensor. You need to lower the window light or raise the light inside to better balance the interior and exterior brightness. Basically if the highlights are over four stops over your exposure you are going to get problems like this.
    Probably close to impossible to correct well in post, but not too difficult to prevent at time of capture.
     
  47. Thanks Scott! That's what I've been thinking, but thought it was worth a shot to put it out there!
     

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