I'm probably going to regret this, but at the link supplied in the previous post, particularly relevant information is found in the section labeled "Diffraction-limited imaging."
Anyone can read that whole section — it isn't too long — but here's a crucial fact:
"Thus, the larger the aperture of the lens compared to the wavelength, the finer the resolution of an imaging system. This is one reason astronomical telescopes require large objectives, and why microscope objectives require a large numerical aperture (large aperture diameter compared to working distance) in order to obtain the highest possible resolution." [emphasis added]
To anticipate misinterpretation, this does not mean that one must always choose the very largest aperture, nor that the largest aperture will always be the sharpest one on a given lens for reasons relating to other aspects of lens design and construction. In addition, digital sensors are limited in their ability to record image detail by the nature of digital sampling — in short, higher photo site density, all else being equal, will let the sensor take advantage of higher resolution lenses and apertures.
Also to anticipate misinterpretation, this does not mean that there are never reasons to choose a smaller aperture that will produce an image that is affected more by diffraction blurring. In this thread, I and others have been crystal clear about this. If the only concern is maximum resolution in the center of the frame, then using an excellent lens at its diffraction-limited aperture could make sense. But other photographic concerns, such as a desire for thinner DOF or thicker DOF (and various exposure-related issues) may lead a photographer to choose other apertures than the diffraction-limited aperture.
I'm probably going to regret this, but at the link supplied in the previous post, particularly relevant information is found in the section labeled "Diffraction-limited imaging."
Anyone can read that whole section — it isn't too long — but here's a crucial fact:
"Thus, the larger the aperture of the lens compared to the wavelength, the finer the resolution of an imaging system. This is one reason astronomical telescopes require large objectives, and why microscope objectives require a large numerical aperture (large aperture diameter compared to working distance) in order to obtain the highest possible resolution." [emphasis added]
To anticipate misinterpretation, this does not mean that one must always choose the very largest aperture, nor that the largest aperture will always be the sharpest one on a given lens for reasons relating to other aspects of lens design and construction. In addition, digital sensors are limited in their ability to record image detail by the nature of digital sampling — in short, higher photo site density, all else being equal, will let the sensor take advantage of higher resolution lenses and apertures.
Also to anticipate misinterpretation, this does not mean that there are never reasons to choose a smaller aperture that will produce an image that is affected more by diffraction blurring. In this thread, I and others have been crystal clear about this. If the only concern is maximum resolution in the center of the frame, then using an excellent lens at its diffraction-limited aperture could make sense. But other photographic concerns, such as a desire of thinner DOF or thicker DOF (and various exposure-related issues) may lead a photographer to choose other apertures.
I'm probably going to regret this, but at the link supplied in the previous post, particularly relevant information is found in the section labeled "Diffraction-limited imaging."
Anyone can read that whole section — it isn't too long — but here's a crucial fact:
"Thus, the larger the aperture of the lens compared to the wavelength, the finer the resolution of an imaging system. This is one reason astronomical telescopes require large objectives, and why microscope objectives require a large numerical aperture (large aperture diameter compared to working distance) in order to obtain the highest possible resolution." [emphasis added]
To anticipate misinterpretation, this does not mean that one must always choose the very largest aperture, nor that the largest aperture will always be the sharpest one on a given lens for reasons relating to other aspects of lens design and construction. In addition, digital sensors are limited in their ability to record image detail by the nature of digital sampling — in short, higher photo site density, all else being equal, will let the sensor take advantage of higher resolution lenses and apertures.
Also to anticipate misinterpretation, this does not mean that there are never reasons to choose a smaller aperture that will produce an image that is affected more by diffraction blurring. In this thread, I and others have been crystal clear about this. If the only concern is maximum resolution in the center of the frame, then using an excellent lens at its diffraction-limited aerate could make sense. But other photographic concerns, such as a desire of thinner DOF or thicker DOF (and various exposure-related issues) may lead a photographer to choose other apertures.
