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Blades covering mirror don't close - help!


proust

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If I take the lens off my Xsi camera, the blades covering the mirror don't close and I can see the mirror. The

camera is turned off and the battery is charged.

 

When I first got the camera (a month ago), I remember that they were closing when there was no lens mounted. Any

idea why they're not closing now?

 

Thanks,

Kunal

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If I remember correctly I (think) I saw that when the lens was taken out, the camera would automatically spin little plastic blades into place to cover the mirror (and to ostensibly prevent dirt from hitting the mirror). But if the mirror is always supposed to be exposed when the lens is off (which sounds a bit scary to me), then I guess it's not malfunctioning...
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<P>Kunal writes, <I>"If I remember correctly I (think) I saw that when the lens was taken out, the camera would automatically

spin little plastic blades into place to cover the mirror (and to ostensibly prevent dirt from hitting the mirror)."</I></P>

 

<P>Whatever you were smoking, I want some of that!. Musta been killer sh!T!</P>

Sometimes the light’s all shining on me. Other times I can barely see.

- Robert Hunter

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Laugh if you want, everyone, but I think Kunal inadvertently "invented" a feature that could be enormously useful in DSLR design. Imagine the implications! As you twist the lens, protective blades shield the mirror box from air currents and dust. By the time you pull the lens off, the box is completely covered. Then have the "sensor clean" function open the blades for access -- or perhaps have a separate "mirror box clean" function for blowing out any dust that might have made it past the blades.

 

Brilliant!

 

If this feature were combined with lens/body design that wouldn't draw air through the mirror box (when the lens is zoomed and focused), that would be a winning combination.

 

Kunal, that one might be worth a patent. Of course defending the patent against the likes of Nikon and Canon would be pretty tough.

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Well, at-least I know that the camera isn't malfunctioning. Phew!

 

And actually, like Sarah says, the idea isn't all that far-fetched. My simple Sony P&S camera already does that. Granted, a lens can't be mounted on it and so it *needs* to have a protective covering keeping the lens safe but as far as the technology goes, it isn't something that's way out-of-the-box. I live in the rainy pacific Northwest and the idea of changing lenses while I'm hiking in the rain w/o having a basic level of protection to prevent water from getting to the mirror is actually quite unnerving.

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"the idea of changing lenses while I'm hiking in the rain w/o having a basic level of protection to prevent water from getting to the mirror is actually quite unnerving."

 

Well, if I were you, I wouldn't change lenses in sprinkly conditions, unless you're standing under a very large umbrella. Moisture inside a camera is a horrible thing!

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Wouldn't be too great with rain as the drops would drain inside the mirror box once the lens is mounted. Also, the additional

bulk and cost of a front shutter would be prohibitive--especially all the repairs of EF-S and other protruding rear element designs as they

crash through the shutter...

Sometimes the light’s all shining on me. Other times I can barely see.

- Robert Hunter

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It seems like it would be a cool idea to have protective covers over the lens, but really it would only be another thing to break. If it was made of a very heavy metal it would be safe, but way too expensive and would add lots of bulk. If it was just like the little plastic shutters on point and shoots it would fail quickly. I've seen MANY point and shoots with the front lens cover jammed. People would think they were safe from dust, but after a day at the beach the "protective" shutter would be stuck, and the camera would need repairs.
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No Puppy, there's room. If you think about it, a front shutter could sit back in the mirror box a short distance, so long as the mirror isn't raised. Thus it would clear the lens and the mirror. When the lens is mounted, the shutter opens, creating an opening for the mirror to articulate through it. It wouldn't have to be a robust or elaborate mechanism. Plastic parts would do. So long as people don't get stupid and let sand and water inside, it should be a nice dust barrier during lens changes. Of course this is a moot issue until the manufacturers can devise solutions to the issue of lenses drawing dust through the mirror box. Nevertheless, that's a solvable problem too.
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