Thread: Lenses, are they infinite in resolution?

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  1. #1 Lenses, are they infinite in resolution? 
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    Hi, I had a discussion with a photographer who just bouht a new phantom camera, a 2K+ camera. And he more or less laught at me of the 4K hysteria, telling me that the optics in a lense will not give you more then 2K. That for a 4K picture you needed to have almost a double opening of the lense. I told him "here we see differences in meanings...and teaching..., the 2K camp vs the 4K and 8K camp"

    So my question is:

    Lenses, since they are optical, do have an infinite resolution ? It is only up to the sensor, how small the "pixels" you can get out of the lights coming in, right ?

    cheers Helge
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  2. #2  
    Senior Member Karim D. Ghantous's Avatar
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    I am not an optics expert, but I can tell you that lenses do have limits on their resolution. I can also tell you that the person you were talking to is unintelligent. What he said can be true. But (I am simplifying, now) it depends on the lens and it depends on the width of the photosites on the sensor.
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  3. #3  
    Senior Member Pascal Scheffers's Avatar
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    You cannot have infinite resolution, that physically impossible. Theoretical lenses are mathematical games. In the real world, for starters, each ray of light has a certain size which is small, but not zero. More relevant to lenses is the fact that each color as we record it is a different wavelength and therefore bends differently through the glass. You can fix this to certain degree, which is what 'low dispersion glass' or 'LD' is all about in lenses, and then you stack them (lens elements) to try to get them back together... but you always end up losing resolution. And this isn't the only contributor, heck, I'm not even sure if this is the biggest component of resolution 'loss' in optical lenses.
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  4. #4  
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    Quote Originally Posted by helgetjelta View Post
    Lenses, since they are optical, do have an infinite resolution ? It is only up to the sensor, how small the "pixels" you can get out of the lights coming in, right ?
    Lenses do not have "infinite" resolution. The image is always blurred as it passes through the lens (this is what we mean when we say a lens is "soft"). All lenses blur fine details at some point. Most lenses also can only resolve the finest detail in the center of the lens, and get blurry as you move away from the center.

    Recording a blurry image with small pixels does not make it less blurry. ;-)
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  5. #5  
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    Quote Originally Posted by Pascal Scheffers View Post
    In the real world, for starters, each ray of light has a certain size which is small, but not zero.
    Since light has no mass (being pure energy), I'm fairly certain that photons do not have a "size". They do have a wavelength, though, being electromagnetic radiation; this becomes important in certain situations where the wave-particle duality aspect of light comes into play.

    Point being, I think suggesting that light (photons) have a physical size is incorrect, and I can say with certainty that physical simulations of light do not take into account the "size" of a photon, only the wavelength.

    I think you're actually thinking of the circle of confusion that occurs when light passes through a lens. This may seem like a "beam", giving the appearance that "rays" have a "width", but that's not what's actually happening at the photon level. Hope this helps!
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  6. #6  
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    From Wikipedia:

    Lens resolution

    The ability of a lens to resolve detail is usually determined by the quality of the lens but is ultimately limited by diffraction. Light coming from a point in the object diffracts through the lens aperture such that it forms a diffraction pattern in the image which has a central spot and surrounding bright rings, separated by dark nulls; this pattern is known as an Airy pattern, and the central bright lobe as an Airy disk. The angular radius of the Airy disk (measured from the center to the first null) is given by

    \sin \theta = 1.22 \frac{\lambda}{D}

    where

    θ is the angular resolution,
    λ is the wavelength of light,
    and D is the diameter of the lens aperture.

    Two adjacent points in the object give rise to two diffraction patterns. If the angular separation of the two points is significantly less than the Airy disk angular radius, then the two points cannot be resolved in the image, but if their angular separation is much greater than this, distinct images of the two points are formed and they can therefore be resolved. Rayleigh defined the somewhat arbitrary "Rayleigh criterion" that two points whose angular separation is equal to the Airy disk radius to first null can be considered to be resolved. It can be seen that the greater the diameter of the lens or its aperture, the greater the resolution. Astronomical telescopes have increasingly large lenses so they can 'see' ever finer detail in the stars.
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  7. #7  
    Hei, Helge!

    You´ve gotten a lot of very technical explanations. The real world answer to your question is that any decent 35mm lens resolves more than 4K. Arri recommends at least a 4K scan of film. Those films are shot with 35mm glass. Same thing with DSLR, with the logic of your friend the 12/16/24/etc MP sensors of the cameras would be useless.

    MVH
    Fredrik
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    Quote Originally Posted by Fredrik Harreschou View Post
    Hei, Helge!

    You´ve gotten a lot of very technical explanations. The real world answer to your question is that any decent 35mm lens resolves more than 4K. Arri recommends at least a 4K scan of film. Those films are shot with 35mm glass. Same thing with DSLR, with the logic of your friend the 12/16/24/etc MP sensors of the cameras would be useless.

    MVH
    Fredrik
    You want the optics to be the limiting factor on resolution. You have problems with aliasing and moire when the sensor is the limiting factor.

    Resolution is also relative to sensor size. A lens that would resolve 4k on a 35mm sensor would only resolve half that on a 16mm sized sensor.
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  9. #9  
    REDuser Sponsor Martin Stevens's Avatar
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    Quote Originally Posted by Erich Ocean View Post
    Since light has no mass (being pure energy), I'm fairly certain that photons do not have a "size".
    Since E=mc2 or E=m, photons do indeed have mass and size.
    Regards,
    Martin Stevens

    President and Founder of Glidecam Industries, Inc.
    Producer and Director at Metaphoric Pictures Corporation.
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  10. #10  
    Senior Member Ketch Rossi's Avatar
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    NO, lenses are not made with Infinite resolution...

    Inf act more then once was said that literally all Camera companies have their Glass Obsolete by their Sensor capacity, Including Canon "L" Series, glass,
    and this is why also recent tests with EPIC show that Canon is softest when compared to Red Pro Primes or Master Primes, and that currently the new King of the Block in resolution
    are the LEICA S-C Primes made form Scratch to resolve 8K and above... ;)

    But I must add is way more complicated then this...
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