Nikon patent for ON/OFF optical low-pass filter (OLPF)

Nikon filed a patent application in Japan (2011-97288) for an optical low-pass filter OLPF (aka as anti-aliasing filter) that can be turned ON or OFF depending on the need of the photographer:

"The imaging device by the invention according to claim 1 receives object light via a photographing optical system, The low pass filter component which is arranged in the optical path between the imaging means which outputs image data, and a photographing optical system and an imaging means, and contains the birefringence optical member of a couple."

"The figure showing the important section composition of the electronic camera by an embodiment of the invention"

"The switching means which carries out relative rotating of the birefringence optical member of a couple, and changes the low pass filter characteristic of a low pass filter component between the 1st characteristic and the 2nd characteristic."

"The figure explaining the details of the optical low pass filter in an embodiment and an actuator"

The ON/OFF implementation is mechanical - here is the detailed description of the above drawing:

"The actuator 103 is constituted including the motor 103a, the base 103b, and the transmitting part 103c. The motor 103a is driven according to the driving signal from the control circuit 111. Rear filter 102AFT mentioned above was provided, for example, the base 103b is a disc-like plate. The opening is provided in the center section of the base 103b at the form which is mostly in agreement with the rectangular shape of rear filter 102AFT. And rear filter 102AFT is embedded at this opening, and it is made and joined. The transmitting part 103c is a disc-like plate, and tells rotation of the motor 103a to the base 103b. In accordance with each circumference, the gear etc. are formed so that engagement of the base 103b and the transmitting part 103c may become possible mutually. As a result, if the transmitting part 103c rotates according to rotation of the motor 103a, it will interlock and the base 103b will rotate."

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  • NikonD80Still

    Something might be very useful 🙂

    First one. Where is everyone ???

  • this is interesting….

  • Petia

    Fun, but I’m unsure whether this can have any commercial interest.

    • It’s comparable to the gridlines we can switch on and off in most Nikon bodies. We have the option to chose what we want, which is great.
      Canon bodies don’t have this, they can also get gridlines if they want, but they’ll have to change the focus screen.

      Same with the anti-alias filter, but now everyone who doesn’t want its effect needs to physically remove it…
      Some people don’t care, some people do. Having the choice allows you to experiment and allows you to make sure your camera does exactly what you want. I’d say this is a great option!

      • j

        7D can have gridlines and such on the viewfinder I think (without changing focus screen I mean.

  • some people are paying for removing AA filter, this is a nice feature.

    • M Jesper

      Exactly. I like it ! More control over the crispyness of sharpness. And i love that it’s ‘mechanical’ and not just a post-processing filter. ‘I’d turn the AA way up because i really hate jagged edges, and i think (that much) sharpness is overrated. Put it in the D800 please !

  • kede

    This looks like there will be some really nice video functionnality on the new cameras.

  • Jabs

    Seems like Nikon is returning to the flexibility of the F thru F5 series and giving us many more options but now electrically done instead of mechanical things.
    This looks good and should make for a more versatile camera as far as the diverging needs of photography and video go.
    Can’t wait to see what they ‘cook up’ in the D4 line and later.

  • Imagine the fun when you’re trying to clean your sensor 😉

    • BornOptimist

      You mean? elaborate…
      The filter is not removed, it’s just rotated. It’s described in text above.
      There are also filters in front of, and behind the low pass filter, so you’re never in contact with the low pass filter when cleaning the sensor.

      • Yup… my bad. Didn’t see 102FWD.

        Still… I’d like them to make a working prototype and have it tested out in the field. That would be the day.

  • Sam

    This could be awesome, using the filter when shooting clothes, screen doors, etc. And turn it off when you want that extra sharpness (although you’ll have to deal with the line aliasing then). Hoping this makes it on to the D800 & D4.

  • longzoom

    There will be always regular glass plate to cover the sensor, in case the AA filter is lifted.

    • longzoom

      And extra moire could be removed by camera itself as it is done with CA now.

      • Lawliet

        Removing CA is easy. You have all the information, its just that a clearly defined subset is shifted a bit.
        With moire you have a blend of real and false information and no way to separate that groups reliably. Some educated guesses are possible, but thats not a safe bet. You could just as well end up with more details lost then through an AA filter – but you wouldn’t get the chance to repair the damage via sharpening.

        • Soap

          The camera body has all the information needed to remove moire to any arbitrary frequency cutoff . You are absolutely right in that one can not blindly remove moire without either compromising potential sharpness or failing to remove all aliasing, but what is to stop in-camera processing from low-passing at exactly the same cutoff as the physical filter?

        • Btw CA can’t be removed… only it’s side effects (fringes) can be hidden. The data lost from CA is… well… lost data.

          Shoot the same scene with a lens without CA and you’ll see the difference.

  • Dave

    Obviously good news for the IR crowd.

    • D-7

      Irreveland for the IR crowd (happy crowd member myself too). AA filter is not the same as the hotmirror.

    • Lawliet

      While the hot filter and AA filter often are the same assembly you won’z get a thing. That setup doesn’t remove the filter, but rather works like a polarizer. The strength of the low pass effect depends on the angle of rotation between the layers of the AA filter.

  • gallon

    Low pass filter? Does that mean this thing switches IR?

    • D-7

      It’s not the hotmirror that gets removed, as far as I understand.

    • Soap

      IR is below the visible part of the spectrum.
      The hot mirror (IR filter) is a HIGH PASS filter.

      • gallon

        Sez in the title that this contraption is low pass.

        • Soap

          and it is.

          I was answering the confusion about IR filters, which ARE high pass.

  • Jeff1

    This sounds like a great idea! I hope this patents gets put into production soon.

  • big eater

    It cannot come too soon. This is the kind of flexibility that would make Nikon stand out from the other camera makers once again. Combined with the great Nikkors, this could get us very close to medium format quality.

  • Hope this makes to new generation of Nikon cameras!

  • Great! Whatever when this would be implemented, will wait for this.

  • cool idea, so i will not be forced to disassembly the camera.

  • Hmmm…if 102 AFT rotates and 102 FWD stays put, the only filter that already does that kind of thing is a polarizer. So are they putting in a polarizer? Or perhaps a vari neutral density filter, which also does that.

    • Lawliet

      The only commonly used kind is a polarizer – but you can create microstructures that do different things. Think of microlenses/beam splitters that either spread the light in a two stage process or cancel each other out if reorientated.

    • Soap

      Variable ND = two polarizers. This is not based on polarization but (as Lawliet says) aligning and unaligning microstructures in two films to achieve variable “milkiness” (which is what an AA filter is).

  • longzoom

    If it is a pola system, what about fishes and ultra-wide lenses? I am not sure I fully got the idea, then…

    • Even with ultra-wides you sometimes need to decrease amount of reflections. In the forest, for example, where the sky is closed by high crowns of trees.

    • Soap

      It isn’t a polarizer. Think of it as a variably milky filter.

  • Camaman

    So one or two important questions:
    How do I know if I won’t ruin my photo by lifting the filter?
    Will the camera judge the scene and beep if potential moire occurs?

    • Lawliet

      You won’t know until you have a picture, in a suspicious scene a slight nudge one on the zoom or focus ring or even the aperture setting might tip the scales the one or the other way.

      With LV or after the shot the camera could warn you about certain color patterns. But it can’t tell for sure if its moire or a funny fabric

  • longzoom

    Camera already shows washed out highlights. But moire, as noted above, is much more difficalt problem.

  • MW

    Wouldn’t a ND Filter instead be more interessting? 1 to 5 stops maybe???
    That would make flash photography much easier in sunlight

  • regular

    The next one which makes a stupid comment and hasnt read the wikipedia article about ‘birefringence’ will get a punch in the nose!

    • Rude-olf

      Wikipedia: The source of all confusion.

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