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Author Topic: Patent: A Pellicle Mirror by Canon  (Read 9341 times)

neuroanatomist

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Re: Patent: A Pellicle Mirror by Canon
« Reply #30 on: November 01, 2013, 01:00:29 PM »
If canon made a mirrorless 6D - size, etc being the same with a really good EVF...

Well, much like avoiding Imperial entanglements, that's the real trick, isn't it?
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Re: Patent: A Pellicle Mirror by Canon
« Reply #30 on: November 01, 2013, 01:00:29 PM »

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Re: Patent: A Pellicle Mirror by Canon
« Reply #31 on: November 01, 2013, 01:17:51 PM »
If canon made a mirrorless 6D - size, etc being the same with a really good EVF...

Well, much like avoiding Imperial entanglements, that's the real trick, isn't it?

Yep, maybe Canon will surprise.  I won't buy one, but I'm really interested in seeing what the new retro Nikon looks like. They blew it with the 1 series.
« Last Edit: November 01, 2013, 02:13:27 PM by pharp »

hpjfromdk

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Re: Patent: A Pellicle Mirror by Canon
« Reply #32 on: November 01, 2013, 03:07:56 PM »
Have been surveying the machine translation of JP2013-218241 from Japanese into English as provided by JPO a bit...

In terms of prior art JP2013-218241 initially references JP2002-182268 which deals with a DSLR having a 45deg fixed half mirror. This patent does not deal with the half mirror as such but with the fact that a fixed half mirror does not exhibit a “mirror slab” and combined with a low noise shutter the photo taking can be made less intrusive. JP2013-218241 however uses said patent as an example of the inherent light sharing compromise between the OVF and the image sensor and states that a “modulated” mirror is a solution for this problem. As for an example of a modulated mirror JP2013-218241A refers to JP2007-102197 aka US75541551 which deals with electrochromic thin film/multilayer constructs, aimed at controlling heat transfer trough windows in houses and vehicles - in other words sun filters. By applying voltages of different polarity to the appropriate layers, the optical properties of the construct can be changed between a state with transmittance/reflectance of 0%/27% and another state with 48%/6% respectively - with one caveat though, the switch from low to high transmissivity takes about 40secs @ λ = 670nm (red/NIR) and the other from high to low transmissivity about 15secs. 

JP2013-218241 in its embodiment goes on to state that since light measurement is made on the OVF path and to ensure adequate OVF brightness at low light levels the reflection towards the finder should not be less than 60% (40% left for phase detection on the image sensor). An interesting aspect of the patent app is that the modulated mirror not only removes the mirror slab but also replaces the shutter – thus constituting a virtually noise free DSLR. The patent mentions both a still and an “animated” mode with up to 15 frames/sec.

For those interested there is also the Canon patent app US20130002925 which also deals with a modulated mirror, or in this case referred to as “variable translucency” mirror. The technology used to achieve any level of translucency/reflectance between 100%/0% and 0%/100% respectively is based on so called “Micro blinds”, aimed at windows and automotive use as detailed in US7684105.

Surely, - only Canon knows what is going on in their “skunkworks”, but I see some substantial challenges for this type of modulated mirror technology that need to be overcome before a camera using this principle will materialize. For JP2013-218241 would include optical state switching speed, transmissivity, durability (i.e. lifetime), environmental sensitivity, and color casts and for US20130002925 the most obvious ones would include durability (i.e. lifetime), diffraction (even though this is considered US7684105), light incident angles when applied to a 45 deg mirror.

I personally would therfore not bet on seeing a camera based on either of these patents anytime soon, and view this mostly as a “possibly applications of technologies not initially intended for use in cameras and hence preventing others from doing it first” type of patent apps..

But as we all know however, prediction is a skilled art, especially when it comes to the future..
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Re: Patent: A Pellicle Mirror by Canon
« Reply #33 on: November 02, 2013, 05:45:36 AM »
MILC sales numbers are low due to one reason only: rather unattractive MILCS so far. EOS-M ... Nikon 1 ... or mFT.
As soon as really good MILCs are availbale, DSLR sales will fall, MILC sales will rise. As simple as that.
Sony A7/R are the turning point, even if their sales should turn out to be disappointing. Why? Because it has been proven, that cameras with large and good sensors don't need to be large, clunky and heavy.
As afra as lenses are concerned: probably 90% of all images are captured at focal lengths that can be build into small and light lenses. Only a small minority of photographers really NEED to use longer focal length lenses that will be large and heavy as long as glass-based optics are not replaced by something better.

As far as the "variable transmission tech" is concerned: I would prefer Canon to look into this NOT for pellicle mirrors but for fully electronic shutters and possibly also for fully electronic lens apertures, perfgeclty round at any opening - instead of mechanical iris / blades.

I'd love to finally get a 100% digital, electronic camera, devoid of any pre-historic mechanical ballast from the phtographic stone-age. No mirror slap. No shutter-cracking, no shutter-cocking/re-winding. No vibrations. No noise. That is my idea of "pure photography" [ (c) Nikon ;-)] ... in "pure silence".

Imaging with light. Arranging incoming photons. Rather than wielding mechanical and chemical contraptions. Luckily we got rid of the chemical stuff. Now it's time to unload the mechanical stuff too.

dgatwood

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Re: Patent: A Pellicle Mirror by Canon
« Reply #34 on: November 03, 2013, 08:38:01 PM »
Mirrorless offers the potential for no shutters....

AFAIK, there's no reason you couldn't do a shutterless traditional DSLR.  Honestly, I'm surprised DSLRs even still have a shutter.  It's a vestigial organ that can be made completely unnecessary by proper buffering (which is also the way you fix the rolling shutter problem in video mode).

eninja

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Re: Patent: A Pellicle Mirror by Canon
« Reply #35 on: November 03, 2013, 09:08:05 PM »
Please explain to me how adding a partially reflective surface into the optical path, and at an angle to boot, is going to improve image quality?

This is a bad idea. Period.


Um.. Technology Improvement?
Partially reflective surface: When light hits an object part of it is reflected, transmitted, and absorb by the object. You ask how adding an object into optical path improve image quality, isn't it longer lens got more elements on it than a prime lens, but we never question its optical transmission quality.
Similarly with this scenario, adding an high light transmittivity material wont affect image quality much. if we can possible vary the reflectivity/transmittivity of material in a high quality, then i dont see any problem.

I hope I got a point. But cheers.

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Re: Patent: A Pellicle Mirror by Canon
« Reply #36 on: November 10, 2013, 07:22:46 AM »
Done right it could be a perfectly good idea where the gains far, far outweigh the loss of a little bit of light. Even the Sony SLTs weren't that bad imo.

Some people go anal over 1/3 stop of light. OK I obviously understand the significance of light in general, but if a camera this mirror thing improved ISO to compensate, I'd gladly take the very high FPS, no "mirror blackout" and if armed with a (very fast and hi-res) EVF it'd also have a live view of the exposure.
And all the above will improve, because technology always does ...

As for that bit of light loss, different lenses, different brands already can vary by 1/3 stop if not more of light anyway in their native designs. So you better check all your lenses if you're that paranoid losing light  ;)

(cue usual elitist posts on how such "features" are a crutch and not real photography)
Hurry up Canon and do something with your sensors! :P

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Re: Patent: A Pellicle Mirror by Canon
« Reply #36 on: November 10, 2013, 07:22:46 AM »

rsdofny

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Re: Patent: A Pellicle Mirror by Canon
« Reply #37 on: November 11, 2013, 08:09:49 AM »
Canon needs a WOW product badly: maturing DSLR market, smartphone undercutting all the compacts, Sony groundbreaking products like RX100, A7, etcs.  I sense that simply changing color of the body of same old boring products will not cut it.

AvTvM

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Re: Patent: A Pellicle Mirror by Canon
« Reply #38 on: November 11, 2013, 10:39:50 AM »
Done right it could be a perfectly good idea where the gains far, far outweigh the loss of a little bit of light.

No. Pellicle-mirrored = does nothing, a mirrorless camera will not do much better.

Mirrorless actually combines EVF (considered as a disadvantage by many DSLR users) and all the bulk of a DSLR. Plus light loss and possible degradation of IQ due to reflections on top. That's one of the reasons, why Sony is quitting their SLT line of cameras. Dead end!

jrista

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Re: Patent: A Pellicle Mirror by Canon
« Reply #39 on: November 11, 2013, 07:09:55 PM »
They won't be much smaller, the geometry for a pellicle mirror is the same as a swinging mirror, they should be lighter and less complicated.

However, the "issue" for pellicle mirrors was always durability and light loss, the silvering had to be on the frontside of the mirror so was very delicate, and even the best lost the film about 1/2 a stop, also the light going up to the viewfinder is lost to the exposure. Now if they have come up with an electronically switching mirrored surface that is silvered on the backside they have cracked it and I for one, would find that more interesting than the EVF's around so far.

Totally agree. Some kind of piezoelectric pellicle mirror would certainly tickle my fancy! I'd pick up one of those, for almost any cost, before even looking at a mirrorless with an EVF. I wonder if it is possible, though...to use some kind of electrostatically activated mirror that doesn't result in any light loss when deactivated for exposure...
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Re: Patent: A Pellicle Mirror by Canon
« Reply #40 on: November 11, 2013, 07:22:32 PM »
... Are they there yet? No! But they are getting closer and how long will it be until EVF is superior to optical....

Regarding the emphasized part above...I would say never. I think an EVF could get very close to being "as good as" an OVF, but an optical viewfinder is ultimately only going to be limited by the viewers eyes. There is going to be no limit on dynamic range, only the lens will limit resolving power, it will always work in any light level (i.e. I use my OVF to find stars when doing astrophotography...stars, which have about 0.0020-0.0025 lux), and always updates instantaneously when your scene changes. No matter how you slice it...an EVF will never be "superior" to those things.

Given that an EVF is ultimately dependent upon the sensor for low-light sensitivity, barring some unbelievably radical change in how low light sensitivity is achieved, I don't foresee an EVF ever supporting astrophotography...even with 100% Q.E., more than half the stars in the night sky that are visible with an OVF are going to be lost to noise with an EVF. Dynamic range will never be infinite with an EVF, as the sensor's DR will never be infinite. For an EVF's pixels to be invisible to an eye with 20/20 vision, they would need to be so small that they would filter out a moderate amount of red light, and to be invisible to an eye with 20/10 vision, they would need pixels so small that they would filter out most red light.

I'll probably have no choice, at some point in the future, but to switch to mirrorless. When that day comes, I'll do it as begrudgingly as a human being can begrudge...as from a technical standpoint I do not see how an EVF will ever even be as good as an OVF, let alone superior to one. Personally, I am hoping the classic slap-happy, noisy DSLR lasts for another 50 years...after which point I'll probably be dead, and will no longer care.  :P ;D
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Woody

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Re: Patent: A Pellicle Mirror by Canon
« Reply #41 on: November 11, 2013, 07:42:28 PM »
Mirrorless actually combines EVF (considered as a disadvantage by many DSLR users) and all the bulk of a DSLR. Plus light loss and possible degradation of IQ due to reflections on top. That's one of the reasons, why Sony is quitting their SLT line of cameras. Dead end!

No, the reason Sony quit SLT is simpler than that: poor sales. Cannot touch the sales of Canikon DSLRs. They are now going the route of MILCs... which are... surprise, surprise... not selling well outside Asia either.

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Re: Patent: A Pellicle Mirror by Canon
« Reply #42 on: November 11, 2013, 07:45:57 PM »
...I do not see how an EVF will ever even be as good as an OVF, let alone superior to one.

Well said. That is the reason I sold my entire OMD mirrorless stuff.

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Re: Patent: A Pellicle Mirror by Canon
« Reply #42 on: November 11, 2013, 07:45:57 PM »

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Re: Patent: A Pellicle Mirror by Canon
« Reply #43 on: November 11, 2013, 08:52:00 PM »
as from a technical standpoint I do not see how an EVF will ever even be as good as an OVF, let alone superior to one. Personally, I am hoping the classic slap-happy, noisy DSLR lasts for another 50 years...after which point I'll probably be dead, and will no longer care.  :P ;D
I agree that for the applications you cite an EVF would not be the solution. However I think that we are not likely to see the abandonment of EVFs but rather further improvement.
Perfection is not really necessary to be able to achieve 98% of what a photographer needs to know before pressing the shutter.
I have been photographing a series of jobs over the last week where I dearly would have loved to pre-chimp my shots.
I was in a variety of fast moving situations with varying light brightness and color temp that necessitated rapid shooting and chimping to ensure that the exposure was ok.For the most part I was doing well but I would have realized a whole lot less PP had I gotten closer in camera.

I acknowledge the shortcomings but like RF finders, EVFs have their uses.

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Re: Patent: A Pellicle Mirror by Canon
« Reply #44 on: November 12, 2013, 01:12:52 AM »
as from a technical standpoint I do not see how an EVF will ever even be as good as an OVF, let alone superior to one. Personally, I am hoping the classic slap-happy, noisy DSLR lasts for another 50 years...after which point I'll probably be dead, and will no longer care.  :P ;D
I agree that for the applications you cite an EVF would not be the solution. However I think that we are not likely to see the abandonment of EVFs but rather further improvement.
Perfection is not really necessary to be able to achieve 98% of what a photographer needs to know before pressing the shutter.
I have been photographing a series of jobs over the last week where I dearly would have loved to pre-chimp my shots.
I was in a variety of fast moving situations with varying light brightness and color temp that necessitated rapid shooting and chimping to ensure that the exposure was ok.For the most part I was doing well but I would have realized a whole lot less PP had I gotten closer in camera.

I acknowledge the shortcomings but like RF finders, EVFs have their uses.

Oh sure. I'm not advocating abandoning EVFs. I'm all for technological improvements when and where we can make them. I think EVFs can and will be quite useful in certain circumstances. Some EVFs in use for high end cinematography are already quite good, and excessively expensive on a per-part basis. Those costs will come down, and they service their niches quite well.

My concern is that someday EVFs will ultimately replace OVFs.

There is this strange fervor over miniaturization and elimination of the mirror. Its like a fashion fad that just won't die. I don't quite understand it. Not one single mirrorless camera that I've ever held felt good in my hands. I feel cramped, I have to compress my hands in a weird way, and compress the camera and my hands against my face in an uncomfortable way. Miniaturization certainly has its uses in some areas...we don't want our processors to take up warehouses worth of space, so miniaturization does wonders for computing chips. A reduction in weight is useful as well, however not at the cost of having to work contortionist magic on my hands in order to hold a camera to my face. IQ aside, unless some pros have figured out the magic of one-handed photography, I cannot fathom what it is about these microscopic little cameras that has everyone so radically excited, even raving.

Yet...that's the trend. Fad or otherwise, I do have some honest concerns about EVFs and MILCs replacing good old OVF DSLR cameras WAY too soon. I could possibly get used to a mirrorless camera for landscapes...hell, 90% of that work is done with a tripod and a remote shutter release. But wildlife? Birds? Any kind of action whatsoever? Ergonomically, mirrorless cameras (at least as they are designed today), in their diminutive size with their lackluster EVFs, are an utter disaster....
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Re: Patent: A Pellicle Mirror by Canon
« Reply #44 on: November 12, 2013, 01:12:52 AM »