[bwDraco]

This is being posted in the general DSLR discussion forum as this relates to both the K-5 and K-r.

I was messing around with the mirror and aperture control mechanisms of my K-r (it's not broken), and I found some interesting behavior which seems to be closely related to the mirror flop issue. Here are the relevant steps:

1. With no lens mounted, start Live View.
2. While the camera is in Live View, remove the battery. The shutter will close but the mirror and aperture lever will remain in the up position.
3. Push and hold the aperture lever in the down position.
4. Reinsert the battery and turn on the camera while holding the aperture lever in the down position. The camera will cycle the mirror and shutter in an attempt to reset the mirror/shutter/aperture mechanism whenever a button or other control is actuated, for as long as the aperture lever is held down. When the status display is shown in manual exposure mode, and a button (such as the Green button) is held down while the aperture lever is held down, the seconds field will read 9999". When you attempt to start Live View, the camera will cycle the mirror and shutter about 20 times before the Live View screen appears, but the Live View feed is blank, and the seconds field will read 9999.
5. When you take your finger off the aperture lever, and the camera is not in Live View, the camera recovers once you actuate any control, and will shoot normally. In Live View, the mirror/shutter/aperture mechanism resets when you do so, but the camera will cease to function properly until you remove and reinsert the battery.

If the mirror is held up while the aperture lever is held down, you'll notice that the camera keeps cycling the shutter (it'll move up and down whenever you actuate a control or do so continuously when in Live View).

I was able to replicate mirror overrun behavior on a camera that is functioning normally by holding the aperture lever in the down position. This experiment proves that the real cause of the mirror flop issue is a jammed aperture control lever.

My camera wasn't damaged when I did this and continues to function normally after the lens was put back on the camera, but I'm not responsible for any damage this procedure may cause to your equipment.

Here's a previous post I've made regarding this issue:

At 2:35 and 2:46 in the video, notice that the aperture control lever at the left side of the mount is not moving when the shutter/mirror cycles. On my K-r, this lever always moves up whenever the mirror goes up. This corresponds to the CRIS replacement of the aperture control unit on a K-5 with this problem; see post #39 of K-5 bug - Shutter going off by itself:

After 2 months a CRIS for this exact problem mine supposedly is shipping back today. They said thet they did the following

REPLACED APERTURE CONTROL UNIT
REPLACED APERTURE CONTROL CONTACT PAD AND BRUSHES

We will see if it is fixed this time....

It appears that the aperture control assembly has failed on your K-r. Try pushing up the aperture control lever in the left side of the lens mount. If this doesn't help, your camera is defective and needs to be repaired or replaced.

--DragonLord

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Last edited by bwDraco; 06-12-2012 at 10:52 AM.

[PPPPPP42]

Hmm, I could see the power guzzling live view causing a brownout with a low battery when a person presses the shutter button and if it blinked back on immediately after that might do the same thing as your test without actually pulling the battery. Maybe some people have run into that.

[Giklab]

The mirror flop issue happens with the battery fully charged, not empty. And it's not because of a stuck aperture lever, but a faulty electronic component. Our importer/service company said that a PCB replacement is needed.

[sterretje]

And it's not because of a stuck aperture lever, but a faulty electronic component.

Which results in a stuck aperture lever if I understand DragonLord's post correctly.

[Giklab]

It's a voltage regulator.

[PPPPPP42]

Ah, so his test is accidentally simulating the power cut out from a faulty voltage regulator.

[Giklab]

I'm not saying it's impossible, but that the known issue in the K-5 is not proven yet to be related to the aperture mechanism. However, this might be a different path to the same result, OR it might be that the battery overcharge (which was said to cause this effect) actually effects the shutter via the aperture mechanism.