I saw ghosting on my NHL shots as well as nothing in focus at all (on way too many frames) with my 7D body. I just wish I would hurry and get my replacement body in so I can try again.
apdieb wrote:
I saw ghosting on my NHL shots as well as nothing in focus at all (on way too many frames) with my 7D body. I just wish I would hurry and get my replacement body in so I can try again.
Be sure to keep us posted. I value your opinion in this matter
7D mazing, ACR vs. DPP (the way DPP tends toward zipper artifacts seems to help break it up into dotted lines a bit and it also appears to do something or other to smooth out smooth areas of the photos to help hide it, but it still looks odd compared to say from a 20D, so i'm not sure it is really trying to perfectly adjust for different gains before doing demosaic, there is clearly noise lined up along straight lines in a pretty patterned way even with DPP)
Fred Tedsen wrote:
I'd be happy to send you the RAW file. How should I go about doing that?
This is the difference of dcraw's 3-color and 4-color interpolations of Fred's image, overlaid in difference mode in Photoshop, and a 4 stop levels adjustment applied, downsized to 1000px across:
If the green channels were balanced, the image should be a uniform gray. Instead, not only does the gray level vary across the image, indicating that the green channels are imbalanced at the few percent level; but there is a chromatic variation to the difference consistent with the colorchecker examples, showing most strongly in yellows and cyans.
It really begins to look as though there is either a) a manufacturing flaw in quite a few copies; or b) a distinction in the spectral response of the two green channels.
ejmartin wrote:
This is the difference of dcraw's 3-color and 4-color interpolations of Fred's image, overlaid in difference mode in Photoshop, and a 4 stop levels adjustment applied, downsized to 1000px across:
If the green channels were balanced, the image should be a uniform gray. Instead, not only does the gray level vary across the image, indicating that the green channels are imbalanced at the few percent level; but there is a chromatic variation to the difference consistent with the colorchecker examples, showing most strongly in yellows and cyans.
It really begins to look as though there is either a) a manufacturing flaw in quite a few copies; or b) a distinction in the spectral response of the two green channels. ...Show more →
(when viewed at 100% one of the blend directions for the original 7D showed the most mazing)
It would be interesting to compare the new one with the old one shot under identical conditions -- I imagine the indoor tungsten would be the one you could come closest to reproducing the exact lighting of the previous test.
Were these processed identically? It looks like the 5D result is at least a stop less imbalanced, and more uniform overall, if so.
ejmartin wrote:
It would be interesting to compare the new one with the old one shot under identical conditions -- I imagine the indoor tungsten would be the one you could come closest to reproducing the exact lighting of the previous test.
Were these processed identically? It looks like the 5D result is at least a stop less imbalanced, and more uniform overall, if so.
I think I just slid highlights in the levels setting down to 27 for all of them and did nothing more so I believe the processing was the same on all. I didn't run it on my old 20D/40D/50D files yet but I bet it might even be more uniform with a couple of those than with the 5D2.
I have a tungsten version from the first 7D stashed somwhere on my HD and sometime on thursday i should be able to get a cloudy version from copy #2 so they can be directly compared.
edit found the ISO100 tungsten from the first 7D (it definitely shows clearer mazing and more vertical bands, but otoh that one patch is a heck of a lot more even, not sure why the one patch with the new 7D has a weird gradient across it....):
tungsten lighting, ISO100, the dcraw stuff and then the blending stuff in CS4 followed by dragging highlights in the levels tool down to 27
ejmartin wrote:
This is the difference of dcraw's 3-color and 4-color interpolations of Fred's image, overlaid in difference mode in Photoshop, and a 4 stop levels adjustment applied, downsized to 1000px across:
If the green channels were balanced, the image should be a uniform gray. Instead, not only does the gray level vary across the image, indicating that the green channels are imbalanced at the few percent level; but there is a chromatic variation to the difference consistent with the colorchecker examples, showing most strongly in yellows and cyans.
It really begins to look as though there is either a) a manufacturing flaw in quite a few copies; or b) a distinction in the spectral response of the two green channels. ...Show more →
Thanks Emil. Clearly I did something wrong the first time I tried your procedure.
Questions: is this camera better or worse than other 7Ds you've sampled? What are the chances that any 7Ds are free of this condition? Have you seen any? I notice that skibum is finding that a second copy has it. Have you heard of anyone getting the condition corrected by sending it to Canon, and if I were to send it in what would I ask them to do?
I have to say that even though I knew of these "problems" beforehand, I'm disappointed that my camera has them. I was hoping that perhaps it was just the odd camera that had it, but it's looking as though it's quite widespread if not universal. I've also found that it's really not too difficult to draw out the low ISO vertical banding in shadows. I've taken a couple of images where it's visible at quite reasonable settings.
skibum5 wrote:
7D mazing, ACR vs. DPP (the way DPP tends toward zipper artifacts seems to help break it up into dotted lines a bit and it also appears to do something or other to smooth out smooth areas of the photos to help hide it, but it still looks odd compared to say from a 20D, so i'm not sure it is really trying to perfectly adjust for different gains before doing demosaic, there is clearly noise lined up along straight lines in a pretty patterned way even with DPP)
skibum5 wrote:
[edit found the ISO100 tungsten from the first 7D (it definitely shows clearer mazing and more vertical bands, but otoh that one patch is a heck of a lot more even, not sure why the one patch with the new 7D has a weird gradient across it....):
So have you figured out whether the new 7D is better than the old one, or just different? Do you plan on keeping it? Based on your other comparison between ACR and DPP, do you think that this could be a condition that might go away when Adobe releases official 7D support?
ejmartin wrote:
This is the difference of dcraw's 3-color and 4-color interpolations of Fred's image, overlaid in difference mode in Photoshop, and a 4 stop levels adjustment applied, downsized to 1000px across:
If the green channels were balanced, the image should be a uniform gray. Instead, not only does the gray level vary across the image, indicating that the green channels are imbalanced at the few percent level; but there is a chromatic variation to the difference consistent with the colorchecker examples, showing most strongly in yellows and cyans.
It really begins to look as though there is either a) a manufacturing flaw in quite a few copies; or b) a distinction in the spectral response of the two green channels. ...Show more → Fred Tedsen wrote:
Thanks Emil. Clearly I did something wrong the first time I tried your procedure.
Questions: is this camera better or worse than other 7Ds you've sampled? What are the chances that any 7Ds are free of this condition? Have you seen any? I notice that skibum is finding that a second copy has it. Have you heard of anyone getting the condition corrected by sending it to Canon, and if I were to send it in what would I ask them to do?
I've only examined a handful of 7D's myself; they all exhibit the issue to one degree or another. A few other people (theSuede, John Sheehy at DPR,...) have noticed it as well. I have yet to see a copy that is free of the issue. As I said, it is not yet clear whether this is a manufacturing defect or a design feature. All I can say at the moment is that the two green channels have different response, that varies with hue and saturation, and from column to column (the vertical banding in the difference images).
Scroll down to the Blue Sky shots and you'll see the mazing just like what has been posted on this thread - green channel imbalance is apparently a common and known occurence in many cameras from many manufacturers (it is regularly discussed on the Raw Therapee forum, and never about the 7D! )
It's so pervasive in fact, that you can't help but wonder if it's designed in...
Much of the non 7D discussion about it indicates that better demosaicing algorithms are the solution. Even Adobe is aware of, and considers that it is able to address, artifacts caused by the imbalance: http://forums.adobe.com/message/2321414?tstart=0
As post 7 there says:
Anyway, this simply indicates that there is a bug in Lightroom/ACR. It should not do this as it can clearly deal with unequal green response, and similar problems were fixed for other cameras with unequal green response.
For clarity, I'm not saying that nothing is going on with the 7D, but I am saying that it appears neither to be unique to the 7D nor - on the face of it - terribly intimidating to providers of conversion software...
Scroll down to the Blue Sky shots and you'll see the mazing just like what has been posted on this thread - green channel imbalance is apparently a common and known occurence in many cameras from many manufacturers (it is regularly discussed on the Raw Therapee forum, and never about the 7D! )
It's so pervasive in fact, that you can't help but wonder if it's designed in...
Much of the non 7D discussion about it indicates that better demosaicing algorithms are the solution. Even Adobe is aware of, and considers that it is able to address, artifacts caused by the imbalance: http://forums.adobe.com/message/2321414?tstart=0
As post 7 there says:
For clarity, I'm not saying that nothing is going on with the 7D, but I am saying that it appears neither to be unique to the 7D nor - on the face of it - terribly intimidating to providers of conversion software... ...Show more →
I am very familiar with the discussion at OjoDigital; I am the developer of an advanced demosaic algorithm (AMaZE) which should appear in a future release of PerfectRAW being developed there.
The workaround which is suggested there is an averaging of the green channels, with a concomitant loss of resolution, as I have been saying all along. Any such averaging amounts to a low pass filter being applied to the RAW data. The low pass filtering to equilibrate the greens sacrifices resolution for the purpose of preventing artifacting.
It would be much better, if indeed the problem is a manufacturing defect, to know how widespread it is and to get it fixed. That way the full resolution that the camera is capable of can be extracted in principle. If the issue is rather the design of the CFA, then Canon has decided to sacrifice resolution for some purpose yet to be determined.
It would be interesting to see the 3-color vs 4-color test I suggested carried out on a number of cameras to see if the issue is pervasive, and just worse with the 7D, or if it is rather unique to the 7D in Canon's lineup. The one example skibum posted from a 5D2 indicates there is much less green imbalance on that camera.
ejmartin wrote:
I am very familiar with the discussion at OjoDigital; I am the developer of an advanced demosaic algorithm (AMaZE) which should appear in a future release of PerfectRAW being developed there.
The workaround which is suggested there is an averaging of the green channels, with a concomitant loss of resolution, as I have been saying all along. Any such averaging amounts to a low pass filter being applied to the RAW data. The low pass filtering to equilibrate the greens sacrifices resolution for the purpose of preventing artifacting.
It would be much better, if indeed the problem is a manufacturing defect, to know how widespread it is and to get it fixed. That way the full resolution that the camera is capable of can be extracted in principle. If the issue is rather the design of the CFA, then Canon has decided to sacrifice resolution for some purpose yet to be determined.
It would be interesting to see the 3-color vs 4-color test I suggested carried out on a number of cameras to see if the issue is pervasive, and just worse with the 7D, or if it is rather unique to the 7D in Canon's lineup. The one example skibum posted from a 5D2 indicates there is much less green imbalance on that camera. ...Show more →
I will run it on my old 20D/40D/50D files and post back.
My guess is they will show it even a little less than with my 5D2.
It is interesting that in the sample I posted above you can clearly see the darker dots in the DPP conversion lining up in straight maze-like lines even if they mask the effect in the smooth areas somewhat, so it is not like even DPP from Canon actually completely avoids all issues as some earlier talk had suggested.
It seems like it would be a weird decision to go to a 4-color array if it would lead to either some extra noise or some loss of detail when they are bragging about how great the reach and detail are and how low the noise is now.
I will fire off an email to canon tech support too and see what they have to say about it.
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