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09-17-2016, 09:07 PM   #1
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How torquey is your K-1's mirror?

Does anyone notice their body skip a bit when the mirror goes up and down? I can feel it in my K-1. The motor moving it up and down must have twin turbo scrolls inside of it!

09-17-2016, 09:38 PM   #2
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Yes, coming from the K5 the movement from the mirror is really noticeable. MUP gets a good work out.

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09-17-2016, 10:01 PM   #3
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I was only noticing this yesterday when doing some slow and deliberate shooting.....
09-17-2016, 10:38 PM   #4
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The floating sensor block can also be felt when SR is fixing it or releasing it. That's ok, I like that feeling and I'm still amazed that Pentax are able to have a floating sensor block and no vibration, reliability or thermal issues (what Canon are concerned with). What's interesting to me is that Nikon had issues (light leak, and oil on sensor) that Pentax (smaller company) does not seem to have.

09-18-2016, 01:52 AM   #5
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QuoteOriginally posted by 6BQ5 Quote
The motor moving it up and down must have twin turbo scrolls inside of it!
It could actually be caused by less efficient counterweights. Canon and Nikon does counterweight and dampen the mirror shake extremely well. Thats why their top full frame models can do 10+ fps with mirror flapping and still get reliable AF detection. Quite incredible.

QuoteOriginally posted by biz-engineer Quote
That's ok, I like that feeling and I'm still amazed that Pentax are able to have a floating sensor block and no vibration, reliability or thermal issues (what Canon are concerned with).
I think Sony sensors are much more resistant to thermal noise then Canon sensors, so that would make sense.
09-18-2016, 05:34 AM - 4 Likes   #6
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Mmmmm. Torquey.

09-18-2016, 08:00 AM   #7
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Nice one, @dcshooter!

I'm glad to hear I'm not the only one noticing the movement of the mirror and feeling its inertia. My hope is that this will be a reliable system. I mean, nobody could have guessed the aperture lever system in the K-30 would start breaking down until it did.
09-18-2016, 10:39 AM - 1 Like   #8
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QuoteOriginally posted by 6BQ5 Quote
Does anyone notice their body skip a bit when the mirror goes up and down? I can feel it in my K-1. The motor moving it up and down must have twin turbo scrolls inside of it!
Pentax K-1 uses different mirror movement mechanism than previous cameras. More info here: Challengers | PENTAX K-1 Special site | RICOH IMAGING

At the same time, the engineers in charge of developing a new mirror-driving mechanism faced the difficulty of designing the ideal mechanism from the very beginning. The space given to them was simply too small. Although they were initially hoping to adopt a simple mechanism that drove the mirror along a single axis of rotation, they immediately found out that the installation of such a mechanism would be impossible.

There were two reasons behind this. The first was that the PENTAX K-1 had no spare room in its fringe back — the distance from the imaging plane to the lens mount. Since the fringe back is the base of all K-mount lenses, it is unchangeable. In the case of digital cameras, however, a filter is placed in front of the image sensor. Coupled with the thickness of the SR unit, the shutter unit must be offset toward the lens mount. As a result, the distance from the lens mount to the shutter becomes shorter.

The second reason was PENTAX’s insistence in providing a nearly 100-percent field of view. In order to assure a light flux large enough for such a wide-view finder, the camera must be equipped with a large main mirror. Since the PENTAX K-1’s SR unit shifted the image sensor horizontally and vertically, however, its shutter window became larger. In order to cover such a large opening, the main mirror had to be driven over a greater distance.
“In this case, the main mirror bumped against the lens mount,” explained one of the team members.“With some lenses, the rear optical elements may penetrate into the mirror box. In order to design a lens mount that could accommodate this problem, we decided to adopt a link mechanism in the earliest stages of development.”

In the link mechanism, the pivot shifts its position as the mirror swings up and down. Since it requires a complex mechanism, very few cameras use it these days. The task assigned to the PENTAX engineers was how to refine and advance this mechanism to meet today’s demands.
On one engineer’s desk, you can still find the paper model of the mechanism he created for team discussions. His paper model was helpful for the team members in visualizing the mirror movement, and greatly contributed in drawing them to the conclusion: the pivot of the main mirror would be positioned inside the shutter window before exposure, and would be lifted diagonally and backwards as the mirror swung up. This action would be regulated by a mechanism consisting of a motor, cams and levers.

What makes this mechanism so special is its remarkable position control accuracy since the lever is used to support the pivot, and the lack of positioning errors since no spring is used. “By using the advantages of the link mechanism and optimizing the motor’s regulation and transmission mechanisms, we succeeded in minimizing mirror bounce caused at the swing-down position,” said an engineer in charge of mirror mechanism development. In fact, the PENTAX K-1’s mirror bounce is even smaller than that of the APS-C-sized PENTAX K-3, which is theoretically easier to regulate because of its lighter mirror. In the end, the PENTAX engineers gave birth to the innovative Floating Mirror Structure, which drives a large mirror efficiently in a limited space, without the aid of an additional bounce-regulation mechanism or damper.

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