background preloader

Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks
Diffraction is an optical effect which limits the total resolution of your photography — no matter how many megapixels your camera may have. It happens because light begins to disperse or "diffract" when passing through a small opening (such as your camera's aperture). This effect is normally negligible, since smaller apertures often improve sharpness by minimizing lens aberrations. However, for sufficiently small apertures, this strategy becomes counterproductive — at which point your camera is said to have become diffraction limited. Knowing this limit can help maximize detail, and avoid an unnecessarily long exposure or high ISO speed. Light rays passing through a small aperture will begin to diverge and interfere with one another. Large Aperture Small Aperture Since the divergent rays now travel different distances, some move out of phase and begin to interfere with each other — adding in some places and partially or completely canceling out in others. Diffraction Pattern Airy Disk Related:  Camera Optics Theory

Photon Nomenclature[edit] In 1900, Max Planck was working on black-body radiation and suggested that the energy in electromagnetic waves could only be released in "packets" of energy. In his 1901 article [4] in Annalen der Physik he called these packets "energy elements". Physical properties[edit] The cone shows possible values of wave 4-vector of a photon. A photon is massless,[Note 2] has no electric charge,[13] and is stable. Photons are emitted in many natural processes. The energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ): where k is the wave vector (where the wave number k = |k| = 2π/λ), ω = 2πν is the angular frequency, and ħ = h/2π is the reduced Planck constant.[17] Since p points in the direction of the photon's propagation, the magnitude of the momentum is The classical formulae for the energy and momentum of electromagnetic radiation can be re-expressed in terms of photon events. Experimental checks on photon mass[edit]

Curso de Cromado, Niquelado, Cobrizado, Cromo en Plásticos Lens Genealogy LENS GENEALOGY Part 1by Roger Cicala Where do new lens designs come from?I knew that today’s lenses are all designed using computer programs, but I was surprised to find new lenses aren’t designed from scratch. So camera lenses, like Darwin’s finches, obey a very strict “survival of the fittest” law. Even knowing this, when I wrote a series of articles on the development of camera lenses, I was amazed to find that virtually every camera lens in use today can trace its heritage back to one of five lenses, four of which were developed by 1900. Does the pedigree of a lens matter? Knowing the ancestry of a lens can be interesting from a historical standpoint. Early Lenses DesignsThe first lenses were rather simple things. A mensicus lens (left) and an achromatic doublet After the invention of the Daguerrotype camera lens design improved rapidly and literally hundreds of photographic lenses had been marketed by the early 1900s. The Lens Family Tree The Petzval Portrait lens Advantages: Duh!

Cape Fear Press DSLR Magnification By: Nick Rains We live in ‘interesting times’. Not since colour film was introduced has so much controversy raged about photography. The Internet has allowed vast global discussions to ebb and flow like never before and whilst this is great in some respects, the downside is that there is a whole lot of misinformation floating around. Problem: How to sift the simple facts and truths from the myths and rumours? Answer: With a basic knowledge of certain aspects of photography, especially basic lens theory. Rainbow Lorikeet Canon D60 with Canon 300/2.8L IS lens and 2x Extender (960mm Equivalent Focal Length). The ‘Focal Length Multiplier’ is one of the most easily misunderstood characteristics of the some of the new breeds of DSLR and so I would like to offer a brief look at this aspect of digital imaging and attempt to lay to rest some of the myths. OK, firstly, when you put a 300mm lens on a D60 you do NOT get a 480mm lens – it is still a 300mm lens. Here is the rub. All is not gloomy though.

Dictionnaire raisonné - Taille-douce Previous subarticle GRAVURE, EN TAILLE - DOUCE, | |PLANCHE III. (Page 22:5:3) Les Graveurs sont quelquefois dans la nécessité de réduire les desseins ou les tableaux qu'ils gravent: on trouvera dans nos Planches de dessein les instrumens dont on se sert pour ces sortes de réductions, Pl. II. fig. 16. & Pl. Fig. 1. 2. 3. Nous ne donnons cet exemple que comme une simple ébauche, afin qu'on puisse juger des cho - ses qui doivent être réservées à faire au burin, & en même tems pour suivre l'ordre des opérations. La figure 3. ayant été préparée à la pointe, ainsi qu'on la voit, sera passée à l'eau - forte, c'est - à - dire que l'on la fera mordre, ce qui se fait avec de l'eau - forte à couler, ou avec l'eau - forte de départ; c'est ce qu'on verra dans la Pl. 4. 5. g la même main vûe dans l'action de graver; i le burin vû par le dos; p la planche; o la matiere que le burin enleve, qui se roule en forme de copeau; n la table. 6. 7. 8. 9. 10. 11. 12. 13. Next subarticle

Circle of confusion In photography, the circle of confusion (“CoC”) is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement. Properly, this is the maximum permissible circle of confusion, the circle of confusion diameter limit, or the circle of confusion criterion, but is often informally called simply the circle of confusion. Real lenses do not focus all rays perfectly, so that even at best focus, a point is imaged as a spot rather than a point. The smallest such spot that a lens can produce is often referred to as the circle of least confusion. The depth of field is the region where the CoC is less than the resolution of the human eye (or of the display medium). Two uses[edit] Two important uses of this term and concept need to be distinguished: Circle of confusion diameter limit in photography[edit]

Depth of field and your digital camera What is depth of field? A photographic lens renders a sharp image of points at one given distance, measured along the lens axis. This distance can be adjusted (the process of focusing). Any points at a different distance will be rendered more or less unsharp, and this unsharpness increases gradually as we move away from the "sharp" focus plane. We are talking here only about the unsharpness due to the subject being out of the focused distance. The term depth of field (DOF) is often used to refer to the fact that points not exactly in focus are rendered acceptably sharp in the image. Is it good or bad for your pictures? For many types of photography we would like to have everything in the frame as sharp as possible. In some cases, however, we may want to use a more creative approach, with the main subject of the picture being sharp, while the background (and, if applicable, the foreground) is fuzzy, out of focus. What is "acceptably sharp" — circle of confusion Basic facts The M×A Rule

Sunny 16 rule The basic rule is, "On a sunny day set aperture to f/16 and shutter speed to the [reciprocal of the] ISO film speed [or ISO setting] for a subject in direct sunlight."[1] For example: On a sunny day and with ISO 100 film / setting in the camera, one sets the aperture to f/16 and the shutter speed to 1/100 or 1/125 second (on some cameras 1/125 second is the available setting nearest to 1/100 second).On a sunny day with ISO 200 film / setting and aperture at f/16, set shutter speed to 1/200 or 1/250.On a sunny day with ISO 400 film / setting and aperture at f/16, set shutter speed to 1/400 or 1/500. As with other light readings, shutter speed can be changed as long as the f-number is altered to compensate, e.g. 1/250 second at f/11 gives equivalent exposure to 1/125 second at f/16. An elaborated form of the sunny 16 rule is to set shutter speed nearest to the reciprocal of the ISO film speed / setting and f-number according to this table:[2][3] References[edit] External links[edit]

Lens speed A fast prime (fixed focal length) lens, the Canon 50mm f/1.4 (left), and a slower zoom lens, the Canon 18–55mm f/3.5–5.6 (right); this lens is faster at 18mm than it is at 55mm. Lens speed refers to the maximum aperture diameter, or minimum f-number, of a photographic lens. A lens with a larger maximum aperture (that is, a smaller minimum f-number) is called a "fast lens" because it delivers more light intensity (illuminance) to the focal plane, achieving the same exposure with a faster shutter speed. A smaller maximum aperture (larger minimum f-number) is "slow" because it delivers less light intensity and requires a slower shutter speed. A lens may be referred to as "fast" or "slow" depending on its maximum aperture compared to other lenses of similar focal length designed for a similar film format. Lens speed is important in taking pictures in dim light, or with long telephoto lenses. With 35 mm cameras, the fastest lenses are typically in the "normal lens" range near 50 mm.