Strange banding artifacts with 5D

Discussion in 'Canon EOS' started by jonathan_traupman, Nov 24, 2006.

  1. I had the strangest problem with my 6 month 5D this evening and am hoping someone here can shed some light on what's going on. A friend and I went to take some photos of the sunset over the golden gate (cliche, I know, but bear with me) from the Berkeley hills (one of the parking lots at the Lawrence Hall of Science, for those who know the area). When we got back, all of the photos I shot exhibited a very weird banding artifact -- alternating light/dark strips about 10 pixels wide running diagonally (about 20 degrees from vertical) across the image. It's not severe, but it is noticeable both on screen and in an 8x12 print. It's definitely more noticeable in the shadows or in underexposed shots, but it is present to some degree in every shot I took this evening and some were 1-1.5 overexposed because we wanted to try out HDR techniques. All were shot on a tripod with mirror lockup and a cable release at ISO 100. Shutter times ranged from 1/30s down to 15s as the light faded. Long exposure noise reduction makes no difference. The problem occurred with at least two different lenses. Here's where we enter the twilight zone -- I noticed this problem at home on my computer, so we of course immediately set out to test out the camera. Similar duration shots with the exact same settings taken at home and in my backyard (the cold temperature, about 45F, was our first suspicion) did not exhibit any banding. So we drove back up the hill, put the tripod in exactly the same spot and took a few more shots. Every one had the banding. My current working theory is that there was some sort of RF interference happening up on the hill. It's a logical place for a cell tower or radio transmitter, although we didn't see any in the immediate vicinity. It's also near the Lawrence Berkeley National Lab, which runs particle accelerators that put who knows what kind of radiation. Anyway, has anyone seen a similar problem with their 5D? Is this "normal" behavior for this camera or is there some subtle defect with mine? I can always send it to Canon under the warrantee, but without being able to reproduce the problem outside of the "mystery spot," I'm not sure what they could do.
    00IvZy-33693984.jpg
     
  2. Hi Jonathan,
    Similar duration shots with the exact same settings taken at home and in my backyard (the cold temperature, about 45F, was our first suspicion) did not exhibit any banding. So we drove back up the hill, put the tripod in exactly the same spot and took a few more shots. Every one had the banding. My current working theory is that there was some sort of RF interference happening up on the hill.
    Your current working theory sounds quite plausible to me; however, you might want to be aware of this comment by Chuck Westfall.
    However I do think it's significant that the problem only occurs in the one spot you tried to take your photograph (sounds like my luck!) and the fact that "everyone" had the same issue in the same spot would seem to lend creedance to your theory.
    I eagerly await Canon's next model which will alledgedly address this with a Kryptonite body. ;-) Good luck!
     
  3. Yes it does sound like it might be RFI.

    Some people with similar problems have reported issues with IS lenses, you might want to test with the IS turned off if you were using an IS lens.
     
  4. LBNL may have some pretty powerful magnets, but those should be sheilded.
     
  5. Homeland Security is testing their new plan to thwart pictures of bridges. They are now seeking funding for particle accelerators at other public structures. The military has been doing this for years around Area 51. That's why all the pictures of UFOs are so blurry. That new kryptonite body sounds interesting though.

    I'm surprised you weren't arrested.
     
  6. I think the problem is the 5D and I'll tell you why.
    I spent a full week in June 2006 in SF, and much of that time was spent photographing in and around the GG bridge from all angles and vantage points (including Berkeley Hills)and different times of the day. I never experienced anything like you have. My shots came out perfect, albeit, I was shooting with the 20D. Now, with my new 5D, I've also experienced similar banding which I can't explain, it has nothing to do with bridges or home land security since I live in Canada.
     
  7. jbq

    jbq

    The RF explanation seems quite reasonable.
     
  8. Interesting phenomenon! How about taking shots with lens cap on? That will tell if it is ambient radiation that is causing banding. Also wonder if you were to move the camera around (i.e. no tripod) would you still see banding. From the picture you shared it appears that certain region of the sensor is more sensitive (the upper part seems okay). So if it is non-uniformity of sensor sensitivity you should still see same pattern of banding irrespective of how you hold camera. Good luck.
     
  9. I live in a highrise a block from a TV transmitting tower. The RFI pattern on your image in
    common fare around here. It even interfers with my phones, stereo gear, TV and some digital
    camera images. Doesn't bother film one iota. Luckily I rarely take pictures in my condo.
     
  10. Thanks for all the answers. A little digging on Google turned up a couple of discussions of similar problems with the 5D and 20D, and the conclusions then were RFI as well.

    Here's a few other data points: it's not an IS thing because none of my lenses have IS. It did occur at slightly different locations in the same general area both with and without the tripod. The angle of the bands changed either with time or position (we didn't do enough tests to figure out which). Using the cable release seemed to make it worse. Shots taken from inside the car showed less banding. My friend's 10D didn't appear to be affected at all.

    I'm still waiting to hear back from Canon, but RFI seems to be the leading candidate. The fact that the cable release makes it worse and being inside a metal car makes it better lends further credence to that theory. I just hope they can do something to fix it. I'd hate to have to trade this thing for 1000 rolls of Tri-X....
     
  11. I'm pretty sure it's RFI from all the symptoms you describe and I'm pretty sure there's nothing that Canon can do about it.

    DSLRs are electronic devices and RFI is something you'd expect to be a problem if the RF field is high enough and at the right frequency.

    It happens rarely, but there are places where it will happen. If you MUST shoot in such areas I suppose you could put the camera inside a Faraday cage (with a small hole for the lens) to screen out most of the RF.

    I'm pretty sure that the camera does have screning built into it in the form of a metal chasis and platic parts with a conductive coating sprayed on the inside, but it's hard to provide 100% electromagnetic shielding on a device like a consumer camera.

    See what happens if you cover the camera in aluminum foil...
     
  12. I guess shooting in the car is like a Faraday cage that may be your answer.
     
  13. I missed Bob's response regarding the shielding.
     
  14. Yes, the car is sort of like a faraday cage, which is why we wanted to test it there.

    Thanks, everyone, for your insights. I guess I'll just have to be careful to check the preview images if I'm shooting in the vicinity of cell towers. Either that, or make a tinfoil hat for my camera...in Berkeley, that probably wouldn't even surprise people...
     
  15. I have an even worse case of what I think is the same artifact. I shot it from the peak of Corona Heights in San Francisco. There is not a cell tower or other visiible radio transmiter on the hill. The example I have uploaded is downsampled, not a crop. Everything I shot from that location w/ my 5D and the 400mm "L" at iso 160 and f/6.7, I took a shot moments before from the same location w/ a 20mm lens and it did not have this artifact. Everything I have shot w/ the 5D and the 400 same iso and apeture earlier in the day and the next day did not exhibit this artifact. I also did search corona heights on flickr, not one of the photos exhibit the artifact. It is still a mystery.
    00K3hg-35115784.jpg
     
  16. I know it is a dumb question but did you have your own cell phone switched on?

    Also did it happen on every shot w the 400mm at that location?
     
  17. I have had similar problems with my 5D, but again, like others, not with my 20D, which I also
    use. I am a still photographer for film, and I notice the problem on movie sets where there is
    heavy use of walkies, and other radio transmission devices, and mostly when I shoot at 1600
    or H setting.
    This is hugely annoying, any suggestions of how to sheild would be welcomed
     
  18. EMC is very difficult to predict and manage. At relatively low frequencies (100s of MHz) simple shielding should help, this should be built into the camera design. Many modern PMRs (walkies) are operating at 45 or 60 GHz rather than 200-300MHz and this is much more difficult to screen.

    You could try wrapping foil around the camera, but this kind of homemade fix cam make things worse.

    My suggestion would be to find out what frequency the PMRs are operating on and write a complaint to high levels in the Canon organisation - this might at least get the issue fixed for the "6D".

    I have heard this issue is worse when IS is used, if you are using IS you could try without, a monopod is almost as good if you can get away with it in that environment.
     
  19. I just started having this problem last week. I wasn't anywhere where Homeland Security Might object. I was shooting on the Chicago lakefront on a sunny, hazy day.These were shot at 100 ISO.I just have never seen noise as "linear" before...I thought I was havong problems with my sensor
    00Nuzw-40809584.jpg
     

Share This Page

1111