john_smith232 Posted January 16, 2008 Share Posted January 16, 2008 Hi, I am looking at buying a used 1ds mk II. The owner kindly let me test the camera. When I took the images home I found a small round spot on some of the images (the spot was visible on any shot with an apeture narrower than f16). This spot is a lighter value than the surrounding area. The size of the spot is about the same as a speck of dust on a sensor. Am I wrong in thinking that sensor dust is always darker than the surrounding area and that this spot must be some kind of problem with the sensor? The camera has clocked up 40 000 shutter actuations. Many thanks!<div></div> Link to comment Share on other sites More sharing options...
john_smith232 Posted January 16, 2008 Author Share Posted January 16, 2008 Here is another image where you can see two spots. The spot in the lower right corner is in exactly the same place on the image as the spot in the previous image - they appear to be in different places because of the crops.<div></div> Link to comment Share on other sites More sharing options...
phule Posted January 16, 2008 Share Posted January 16, 2008 It is very unlikely that this is a problem with the sensor. Go back and clean it with a reliable wet method and I think you'll find the spots go away. My guess would be small bits of moisture ended up on the sensor. Link to comment Share on other sites More sharing options...
William Michael Posted January 16, 2008 Share Posted January 16, 2008 A clean, as mentioned above will tell all, IMO. PS: I bet I have more chance of seeing the movie than Rob :) WW Link to comment Share on other sites More sharing options...
william_fong Posted January 16, 2008 Share Posted January 16, 2008 I'd have the owner send it in to Canon for cleaning first. I wouldn't suggest you do the cleaning, just in case something were to go wrong. Link to comment Share on other sites More sharing options...
joedlh Posted January 16, 2008 Share Posted January 16, 2008 Those two spots look like some kind of lenticular effect, as if a water or oil droplet ended up on either the sensor or one of the elements of the lens. That is only shows up at F16 suggests the lens. Did you try to take some shots with another lens? If the spots showed up in the same places, it's the sensor. Otherwise, it's the lens. Link to comment Share on other sites More sharing options...
ronald_moravec1 Posted January 16, 2008 Share Posted January 16, 2008 This will require a wet clean as it is moisture of some kind. I would have the original owner clean it unless he absolves you of responsibility in case it gets screwed up. I will guess he knows it is there and can`t get off himself, in which case you negotiate a lower price based on a repair cost or forget it. 40x is too much anyway. Link to comment Share on other sites More sharing options...
Marvin Posted January 16, 2008 Share Posted January 16, 2008 It doesn't look like the dust on my sensor. Try a blower to remove it. Then, if you know how, clean it yourself with the proper technique or send it back to Canon. Link to comment Share on other sites More sharing options...
john_smith232 Posted January 16, 2008 Author Share Posted January 16, 2008 Thanks very much everyone. I did only test it with one lens - my 50mm 1.4, and so if I buy it, I will make sure the owner is willing to have it cleaned by Canon. Thanks again for your responses! Link to comment Share on other sites More sharing options...
glenn nk Posted January 17, 2008 Share Posted January 17, 2008 I've seen and cleaned many sensor spots, but those don't look like anything I've ever seen. I've never seen dust spots that show up with a white centre. Liquid? What is liquid doing on the sensor surface? The little spot in the second image just below the upper red circle looks like dust but the others really don't to me. Not only have Canon clean the sensor, have them evaluate it - those white centred spots bother me. Sorry, that's just my feeling. Incidentally, spots or dust on or in a lens rarely if ever show up on an image. One of the lenses I have is infamous as some copies suck dust in, but no one actually has seen spots on their images. Link to comment Share on other sites More sharing options...
phule Posted January 17, 2008 Share Posted January 17, 2008 [[Liquid? What is liquid doing on the sensor surface?]] Condensation from the air, Glenn. Or, if you're a mouth-breather like me, you let some spittle get on your sensor the first time you cleaned it. There is nothing wrong with the sensor, it just needs a cleaning. Link to comment Share on other sites More sharing options...
glenn nk Posted January 17, 2008 Share Posted January 17, 2008 I didn't realize that when the OP put his lens on (50 mm f/1.4) that he or the owner had taken the lens off, opened up the shutter (cleaning mode), and breathed on the sensor. I have no idea how long it would take for a "do-drop" to evaporate. Incidentally, I've breathed gently on my sensor as a quick check to detect larger spots - they show up quite well, as will sensor swab tracks. Or perhaps they were cleaning it and the OP just didn't mention that, and too much cleaning fluid was left on the sensor. My sensor fluid evaporates quite quickly, but then I've never spilled a drop on it. Link to comment Share on other sites More sharing options...
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