Permanent sensor dust spots - what is Canon's manufacturing specification?

Discussion in 'Canon EOS' started by mr_marks, May 4, 2013.

  1. I had recently returned my 5D3 to Canon due to permanent sensor dust spots (8 spots) visible at f22 to f8. Canon service confirmed that the spots cannot be cleaned externally and were internal to the sensor. Canon replaced the sensor and upon receiving the 5D3 back, I was surprised that there was still one spot visible at f22 to f16.

    This makes me wonder what is Canon's manufacturing specification for dust spots on their sensor? I would think that the sensors are assembled under clean room environment and should have strict particle control.
     
  2. Yes, they are assembled in a clean room. but people are in there, so it's not perfectly clean (none ever is).
    While if you ever find a 'manufacturing specification' be sure to post it, simply generating dust delete data should compensate for a permanently placed bit. That's been an end user feature on Canons for years. Have you tried it? (I don't have a mk3, but I'm sure it's there)
     
  3. zml

    zml

    Dead/hot pixels and sensor-level flaws are a fact of life, regardless whether this is a 500 or 20000 dollar digital camera/back, Nikon, Canon, PhaseOne or whatever... That's the nature of the beast.
    To add a bit: although there always will be dust, dead/hot pixels, and/or other permanent visual artifacts (as noted above easily handled in digital domain), digital sensors are way cleaner in terms of exposure-time artifacts than film. On pretty much every frame one could see areas this way or another blocked from exposure (pinholes and other shapes), not to mention common dust everywhere, at every stage of processing. I used to spend hours "spotting" the positives with a little brush and an assortment of inks whereas now almost all of it is handled automatically by dust delete data and a click or two in photoshop...
     
  4. Spots internal to the sensor should be small on images because they should be right on the sensor surface, not spaced away from it by the low pass filter. As such they should be easier to clone out.
    Though nobody ever publishes any specs I'd assume that no sensor with 20 million pixels has 20 million perfect pixels. You don't see the bad ones because they are mapped out in the firmware.
    It might also be possible to map out dust spots in the pixel surface (actually more likely on the surface of the microlenses.
    There's no such thing as a 100% clean "clean room". There's always dust. A class 100 clean room has about 10000x less dust than room air.
    I'd assume Canon does have some sort of spec on dust, but it's nothing they are ever likely to publish. It appears that your first sensor didn't meet their specs, otherwise they would not have replaced it under warranty.
     
  5. Pretty soon your camera will have lots of little dust spots due to particles on the surface of the AA filter. Most of those will clean off/move but you'll always have at least 2 or 3 at any given time during regular use. The one that is permanently lodged inside will simply become one of the few. Unless it's particularly big or smack in the centre of the frame I would ignore it and start enjoying the camera whilst it's still a current model.
     
  6. If it takes f/16 to f/22 to see one small spot, it sounds pretty clean now to me. I rarely shoot at those apertures.
    --Lannie
     
  7. If it takes f/16 to f/22 to see one small spot, it sounds pretty clean now to me. I rarely shoot at those apertures.​
    For landscape shooting on FF, F16-22 is pretty standard. Probably F16 accounts for half my landscapes. But I'd be happy to have only one wee spot! Most of my EOS cameras shipped with factory installed dust, so no biggie long as not excessive.
     
  8. Hi mr marks,
    I'm really grateful to you for this post, because I faced the very same problem!
    What a mess, mr marks - Canon replaced your sensor and the new one yet contains a speck? Terrible...
    I wanted to upgrade from my MKII to the MKIII recently. I've meanwhile tested 9 MKIII bodies at 3 different shops / retailers (taking shots of a white sheet of paper at f/20 -22, adjusting the tonal range afterwards etc., I guess, everyone knows the common test procedure...). Result: they ALL(!) showed 4 - 8 clearly visible non-removable specks / dirt and, regarding 3 bodies 2 - 3 hot pixels as well, each! "Non-removable": neither the automatic removal function (regarding all bodies) nor a sensor brush nor a liquid such as Sensor Clean or Eclipse were able to remove the dirt I've viewed (the latter manual procedures I applied to one body of them).
    Hence, I can confirm what mr marks posted here.
    I believe this very serious issue cannot be downplayed. I'm against such an idea of simply mapping out this mess using the firmware.
    I own two 5D bodies, one 5D MKII body, moreover, a 50D and a 20D and think I know a lot about sensor dust, its effective removal and so on. I've never seen before such a dirt / mess on the sensors of my own Canon cameras when I was purchasing them / they were brandnew - they were simply absolutely CLEAN (otherwise I wouldn't have purchased them at all at that time)!
    Note that I frequently take landscape shots using ND filters or in available light at high aperture numbers, hence, a clean sensor is very important to me (although I can easily delete it during PP). I've meanwhile realized / concluded Canon must have a massive QC / QA problem here (maybe due to the fact that the price of the MKIII dropped over the last year significantly?)! Since Fred Miranda had published his remarkable results on the poor performance of the MKIII regarding noise in shadows I already pondered to switch to Nikon's D800.
    If I don't find an entirely clean new MKIII (sensor) soon, I will be switching, for sure! However, if Nikon has got the same problem (what could be read about the D600) I will be holding on, that is, don't buy anything.
    Volker
     
  9. new one yet contains a speck? Terrible...​
    Terrible means really bad. I cannot how see why one dust spot spot can be considered "terrible". I guess I must be blissfully unconcerned about such items. If you change your camera on that basis, I predict you will be gravely disappointed.
     

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