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02-22-2016, 01:39 AM   #1
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Floating Mirror Structure

”Floating Mirror Structure
In order to accommodate the 35mm full-frame image sensor and cover the light flux of the large viewfinder with a nearly 100-percent field of view, it was necessary to increase the size of the main mirror and mirror box. To minimize the size of the mirror box, PENTAX has developed a new mechanism that retracts the main mirror as it swings upwards.”

Features4 | PENTAX K-1 | RICOH IMAGING
Interesting innovation. Hope it won’t provide extra shaking and mirror slap.

02-22-2016, 02:05 AM   #2
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looks like it will also provide a better light seal during long exposures, possibly negating the need for a viewfinder blind.
02-22-2016, 02:44 AM   #3
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QuoteOriginally posted by Digitalis Quote
looks like it will also provide a better light seal during long exposures, possibly negating the need for a viewfinder blind.
Agree
02-22-2016, 08:04 AM - 1 Like   #4
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I'm impressed at the engineering effort Pentax went to with this, to achieve their intent of making the K-1 more compact.

02-22-2016, 08:24 AM   #5
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Something like this was already done on the Minolta SR-T 101
02-22-2016, 11:10 AM   #6
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Also somewhat similar I think to the swiss alpa 35mm, where they did it to reduce registration distance, enabling (standard design) shorter FL lens.
02-22-2016, 10:23 PM   #7
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QuoteOriginally posted by Tjompen1968 Quote
Something like this was already done on the Minolta SR-T 101
Well, it still takes engineering feasability study, mechanical design and development cost to actually implement it in one's own product.

Last edited by KDAFA; 02-22-2016 at 10:29 PM.
02-22-2016, 11:13 PM - 1 Like   #8
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This floating mirror structure, plus the addition of a 2nd reflex mirror to the new AF sensor module in the K-1 to help make the necessarily larger FF autofocus system more compact, highlights the considerable effort the Ricoh engineers put into the K-1. I'm starting to better understand why it took so long to develop.

02-23-2016, 12:24 AM - 1 Like   #9
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QuoteOriginally posted by rawr Quote
his floating mirror structure, plus the addition of a 2nd reflex mirror to the new AF sensor module in the K-1 to help make the necessarily larger FF autofocus system more compact
It will also relieve users of DA lenses from the concern of the larger mirror hitting the rear elements of DA lenses which protrude into the mirror chamber.
02-23-2016, 04:02 AM   #10
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QuoteOriginally posted by Digitalis Quote
It will also relieve users of DA lenses from the concern of the larger mirror hitting the rear elements of DA lenses which protrude into the mirror chamber.
This has never been an issue due to the fact that the flange focal distance is the same on all Pentax and M42 cameras.

---------- Post added 02-23-16 at 12:03 PM ----------

QuoteOriginally posted by KDAFA Quote
Well, it still takes engineering feasability study, mechanical design and development cost to actually implement it in one's own product.
Offcourse.
02-23-2016, 04:22 AM   #11
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QuoteOriginally posted by Tjompen1968 Quote
This has never been an issue due to the fact that the flange focal distance is the same on all Pentax and M42 cameras.
Incorrect - while it is true that the flange is unchanged: the mirror for a full format camera is much bigger than the mirror used in APS-C camera bodies. Certain lenses like the 40mm f/2.8 XS, DA21 or the DA15 have rear elements that protrude further than FA lenses do into the mirror box. The larger mirror, if it remained on its typical arc of movement would in all probability strike the rear element or the surrounding area of certain DA lenses when they are focused at infinity. So Pentax sought to modify the arc of the mirror so DA lenses could be used - it is an elegant solution.

The other upshot of this is that some of the energy from the mirrors upward momentum will be redirected and damped through its movement arc - reducing the effects of mirror slap.

Last edited by Digitalis; 02-23-2016 at 04:31 AM.
02-23-2016, 04:31 AM   #12
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QuoteOriginally posted by Digitalis Quote
Incorrect - while it is true that the flange is unchanged: the mirror for a full format camera is much bigger than the mirror used in APS-C camera bodies. Certain lenses like the 40mm f/2.8 XS, DA21 or the DA15 have rear elements that protrude further than FA lenses do into the mirror box. The larger mirror, if it remained on its typical arc of movement would in all probability strike the rear element or the surrounding area of these lenses when they are focused at infinity. So Pentax sought to modify the arc of the mirror so DA lenses could be used - it is an elegant solution.

The other upshot of this is that some of the energy from the mirrors upward momentum will be redirected and damped through its movement arc - reducing the effects of mirror slap.
In that case I stand corrected
02-25-2016, 12:06 AM   #13
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Actually, Sony had done basically the same thing to provide space for the SteadyShot system in the old A900 full-frame DSLR back in 2008. Sony launches flagship, full-frame Sony Alpha DSLR-A900


Last edited by bwDraco; 02-25-2016 at 12:20 AM.
02-25-2016, 12:16 AM   #14
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QuoteOriginally posted by bwDraco Quote
Sony has done basically the same thing to implement SteadyShot in the old A900 full-frame DSLR
Except that it isn't the same thing. The K-1 mirror is moving slightly backwards as it moves upwards, All SONY has done is add an extra pivot point with two armatures controlling the mirrors movement in parallel, so it doesn't have to move as far.
02-25-2016, 12:32 AM   #15
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Hmm. I took a closer look and it seems they did this to accommodate a larger viewfinder and therefore mirror without the mirror colliding against the mount...

I'm rather confused as to why this is necessary. Perhaps the SR system requires that much more space, similar to Sony's design? (The shutter does need to be large enough to cover an almost medium-format area...)
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