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Thread: Locating a dust bunny

  1. #1
    Alis's Avatar
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    Locating a dust bunny

    Hi everyone,

    I noticed there is a big (~2 mm) dust spot when I look into the view finder of my camera (SLR) but I do not see it on the images. So I am guessing it is on the mirror but not on the sensor, although it is not visible on the mirror. I am sure it is not on the rear element of the lens, because I can see the same spot when I switch lenses.

    Any idea how to get rid of this? I actually thought may be it is higher up somewhere between the mirror and the view finder.

    Thanks,

    Alis

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    Re: Locating a dust bunny

    it might be in or on the pentaprism ..its between the mirror and your viewfinder

    here is a link just showing where it is...http://www.yesmag.ca/how_work/camera.html


    scroll down a little...

  3. #3
    Alis's Avatar
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    Re: Locating a dust bunny

    Quote Originally Posted by kevinbythebeach View Post
    it might be in or on the pentaprism ..its between the mirror and your viewfinder

    here is a link just showing where it is...http://www.yesmag.ca/how_work/camera.html


    scroll down a little...
    Thanks, Kevin. I am not sure how it got there but looking at the picture, I assume with forced air, I can get it out or move it at least. I am very nervous about doing anything near the sensor. And do not have the right tools for it. I remember there was a thead here about it, have to look it up.

    Alis
    Last edited by Alis; 10th September 2009 at 01:42 AM.

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    Re: Locating a dust bunny

    Quote Originally Posted by Alis View Post
    Hi everyone,

    I noticed there is a big (~2 mm) dust spot when I look into the view finder of my camera (SLR) but I do not see it on the images. So I am guessing it is on the mirror but not on the sensor, although it is not visible on the mirror. I am sure it is not on the rear element of the lens, because I can see the same spot when I switch lenses.

    Any idea how to get rid of this? I actually thought may be it is higher up somewhere between the mirror and the view finder.

    Thanks,

    Alis
    Hi Ali,

    It'll be on the focusing screen.

    Easy fixed, and you don't need to go near the senser (in fact, you can't clean it with the shutter open as that would mean the mirror was retracted, which covers the screen).

    Best tool is a 5 inch curved seizure ("artery clamp") (go see one of your buddies in the OR) - pop the lens off and look inside, at the top. You'll see a little black tab (just a couple of mm wide) (it's near the lens mount). Just pull it down (it's connected to a frame that holds the focusing screen that's hinged at the back), and then you'll be able to grab a small plastic tab that's part of the focusing screen and remove it (pay attention to which way it comes out so that you don't put it back upside down).

    Clean with microfibre cloth / blower etc, and re-insert and "job done".

    The sometimes pop loose on the 5D2 anyway, so it's all good practice for you for when that happens. Off memory there are a few youtube videos on how to do it as well, but you shouldn't need them - it's very straight-forward (designed to be done by end users as the focusing screens are user replaceable).

    You CAN blow it out without rmoving it, but all it usually does is just rearrange the spots ... and then of course eventually they work their way onto the sensor

  5. #5
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    Re: Locating a dust bunny

    Wow! Thanks, Colin. I have to admit, it sounds very scary. I have to read this a few more times and see if I have the nerves to do it.

    Thanks again!
    Last edited by McQ; 10th September 2009 at 09:26 PM.

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    Re: Locating a dust bunny

    Quote Originally Posted by Alis View Post
    Wow! Thanks, Colin. I have to admit, it sounds very scary. I have to read this a few more times and see if I have the nerves to do it.

    Thanks again!
    Nah - the thought of performing neurosurgery on someone is scary - cleaning a focusing screen is a piece of cake.

    Here's an idea - do it "doctor" style ... take it down to the OR - cover all but the lens mount with green cloths - don masks/gloves etc (complete with scrub nurse) - and do the clean.

    Oh - and be sure to video the who thing so we can all watch it on youtube -- would be quite funny actually

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    Re: Locating a dust bunny

    Yeah, yeah, just remember not to drip perspiration onto the mirror or that'll be another job.

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    Re: Locating a dust bunny

    Quote Originally Posted by Dave Humphries View Post
    Yeah, yeah, just remember not to drip perspiration onto the mirror or that'll be another job.
    That's what the theatre nurses are there for

    ... just so long as they remember not to suture the lens mount closed when they've finished!

  9. #9
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    Re: Locating a dust bunny

    Actually last night I took the lens off and took a look inside! Never done that before since I always hold the camera face down when changing the lens; and I do it so quickly, there is not time to actually look inside. You camera people have scare us.

    Anyway, I saw the tab you were talking about and I think I can see the dust on the screen.

    No Broadcasting though.

    Alis

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    Re: Locating a dust bunny

    This is something i've thought about. Would you guys do this cleaning as a regulaur thing or when needed. On my camera there is a thing that says shutter up to clean sensor. But after this thread, does this mean in a clean room with loads of people in space suits or should i leave that to nikon
    rob

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    Re: Locating a dust bunny

    Quote Originally Posted by bucketman View Post
    This is something i've thought about. Would you guys do this cleaning as a regulaur thing or when needed. On my camera there is a thing that says shutter up to clean sensor. But after this thread, does this mean in a clean room with loads of people in space suits or should i leave that to nikon
    rob
    Hi Rob,

    We're talking about 2 different things here - Ali is talking about cleaning the focusing screen, but I think your talking about cleaning the sensor.

    Cleaning the focusing screen is optional because it doesn't affect image quality - so it's really only necessary when the "annoyance factor" exceeds your personal threshold. I used to get annoyed at dust on mine, but then the "lazy factor" masked off the "annoyance factor", and I haven't needed to do it for a while!

    Sensor cleaning is another issue altogether; a clean room and a space suit would be nice, but unless you know anyone at NASA (or in the russian space program) then I suspect we might have to make do with more conventional methods! Similar stimulus though (when they start to annoy). Again, I don't clean mine that often anymore -- they only show up at F16 and beyond (unless very big) - and since my shooting style dictates that I usually only post-process 1 shot in 100, it's not an issue to whip through with the healing brush and zap them.

  12. #12
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    Re: Locating a dust bunny

    Quote Originally Posted by Colin Southern View Post

    -- they only show up at F16 and beyond (unless very big) -
    Interesting! Could you please explain this briefly, Colin.

    Thakns,

    Alis

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    Re: Locating a dust bunny

    Here is a link to a pretty good treatise on cleaning DSLRs. This guy has been a camera bug since the 60s(?) or 70s(?) I use his site for info a LOT. Read it carefully, because he does talk about chemical use, but states that was before he found microfiber cloths.

    http://www.kenrockwell.com/tech/cleaning.htm

    Pops

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    Re: Locating a dust bunny

    Quote Originally Posted by PopsPhotos View Post
    Here is a link to a pretty good treatise on cleaning DSLRs. This guy has been a camera bug since the 60s(?) or 70s(?) I use his site for info a LOT. Read it carefully, because he does talk about chemical use, but states that was before he found microfiber cloths.

    http://www.kenrockwell.com/tech/cleaning.htm

    Pops
    Ken's "about" section is compulsory reading first ...

    http://www.kenrockwell.com/about.htm

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    Re: Locating a dust bunny

    While there is a strong caveat in his early writings and there are still a few jokes running about (see "left handed camera") he is now quite serious about his reporting. He does tell you loudly and often that these techniques work for him and you are to proceed cautiously and carefully. That is never a bad idea when working on cameras (or any delicate instrument.)

    Pops
    Last edited by Dave Humphries; 11th September 2009 at 03:06 PM. Reason: correct typo as intended

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    Re: Locating a dust bunny

    Quote Originally Posted by PopsPhotos View Post
    While there is a strong caveat in his early writings and there are still a few jokes running about (see "left handed camera") he is now quite serious about his reporting. He does tell you loudly and often that these techniques work for him and you are to proced=ed cautiously and carefully. That is never a bad idea when working on cameras (or any delicate instrument.)

    Pops
    Don't get me wrong, I like Ken - it's just that I only agree with about 1/2 of what he writes (sensor cleaning being one example) -- it's great that he's never cleaned one - and heaven knows that I like to put it off as long as possible ...

    ... but when the bunny count gets to over a hundred then a mans gotta do what a mans gotta do or else what a mans gotta do just doesn't get done!

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    Re: Locating a dust bunny

    Point taken. Even when I was being tutored by Bill Belknap I didn't agree with all of his stuff. Sometimes, I was wrong.

    Pops

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    Re: Locating a dust bunny

    Quote Originally Posted by PopsPhotos View Post
    Point taken. Even when I was being tutored by Bill Belknap I didn't agree with all of his stuff. Sometimes, I was wrong.

    Pops
    I find that most of the time, the advice given by someone (and I can be guilty of this more than most) is often from people with "tunnel vision" in that they present their advice based on their experiences and normal working practice on the assumption that others will be shooting the same way eg Ken might spend a lot of time shooting at F11 and wider and thus not see sensor dust - and thus assume that it's not an issue for people, whereas I might (in fact do) spend a lot of time shooting at F16 / F22 / F32 where sensor dust can really "pepper" a shot and make for - perhaps - 10 or 15 minutes work per shot (when they're printed BIG you have to pay attention to the really small details; eg I printed a version of my Lone Tree Vista shot 1.6m wide during the week - it was important to go over every inch of it at 100% magnification).

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    Re: Locating a dust bunny


  20. #20

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    Re: Locating a dust bunny

    You blokes still chasing dust bunnies? Do what I do, just throw a ferret in your camera bag.

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