FOV tofocal length

In short, they help photographic subjects appear closer than they are, achieving a beautiful compression for that desirable blurred background. There is a wide range of telephoto lenses on the market, including:

Prime lenses are the unsung heroes of the photography world. Fixed in focal length, they don't have the zoom capabilities of their counterparts, but what they lack in flexibility, they make up for in quality. Because they contain fewer glass elements, prime lenses can capture images that are not only sharper but also more vibrant.

The dioptric power (also called focusing power) of a lens is defined as the inverse of the effective focal length (which is the same is the front and back focal length if the median on both sides of the optics is the same). This means that a strongly focusing lens has a small focal length, but a large dioptric power. For prescription glasses, it is common the specify the dioptric power, whereas the focal length is specified for standard lenses, microscope objectives, and photographic objectives.

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AMS Techno­logies offers a wide range of optical lenses manufactured from high-quality optical glass, but also crystals and other optical materials:

The Model 02-014-1 is an air spaced, computer designed multi-element lens that is diffraction-limited when used with fibers having core diameters as large as 1200 microns. Operational wavelength is 1064 nm. The 02-014 reimages the emitting surface of the fiber with a 0.67× demagnification. Focused spot sizes are significantly smaller than those achievable with single-element lenses used in a similar collimating/focusing configuration. All optical elements are fabricated from high laser-damage resistant glasses and are anti-reflection coated to reduce reflectance per surface to 0.13%. The working distance between the lens and the target is sufficiently large to allow use of a gas nozzle to enhance the cutting or welding process and to prevent debris from depositing on the lens surface.

Explore the world in creative new ways with exceptional G Master performance in a 16-35mm F2.8 wide-angle zoom. This lens delivers consistently superb resolution from corner-to-corner, no matter what ...

A lens with a given focal length <$f$> (taken as positive in the case of a focusing lens) creates a radially varying phase delay for a laser beam according to the following equation:

Various types of optical systems (e.g. microscope objectives and curved laser mirrors) can focus or defocus light, and the focal length is used for quantifying such effects. The simplest case is that of a thin focusing lens (Figure 1a). If a sufficiently large collimated beam of light is incident on the lens, the beam will be focused, and the focal length is the distance from the lens to that focus (assuming that the lens is surrounded by vacuum or air, not by some dense substance with a significant refractive index). For a defocusing lens (Figure 1b), the focal length is the distance from the lens to the virtual focus (indicated by the dashed lines), taken as a negative value. Some authors use different sign conventions, however, in particularly concerning the front and back focal length (see below).

Focal lengthformula

Whether this rule can also be applied to an extended optical system with focal length <$f$> depends on the applied definition of <$f$>. It is useful to specify an effective focal length which is valid for such relations.

If a divergent (rather than collimated) beam hits a focusing lens, the distance <$b$> from the lens to the focus becomes larger than <$f$> (Figure 2). The lens equation states that

Curved mirrors are often used for focusing or defocusing light. For example, within laser resonators curved laser mirrors with dielectric coatings are more commonly used than lenses, mainly because they introduce lower losses.

Note that the locations of the left and right edges of the optical system (e.g. positions of outer lens surfaces, optical windows etc.) or its housing are not relevant for those definitions.

The magic of a prime lens lies in its simplicity. The straightforward optical design enhances light transmission, allowing for incredibly clear and precise images. This can make a noticeable difference in your photography, especially when shooting in low light conditions. Moreover, with minimal distortion and chromatic aberration, your photos will have a professional sleekness that’s hard to achieve with a standard zoom lens.

For a focusing lens, this means a reduced phase delay for increasing <$r$> coordinate. Note that there are different sign conventions in wave optics, where a phase delay can correspond to a positive or negative change of a phasor (complex amplitude).

The equation shows that what determines the minimum possible beam radius is not the focal length <$f$> alone, but rather the ratio of <$f$> to the radius of the open aperture of the lens, which sets a maximum to the input beam radius <$w_0$>. For a focusing or collimation lens, that ratio is essentially the numerical aperture of the lens.

The angle of view of the camera is determined by the ratio of the image size on the film and the focal length. Film-based cameras have for a long time mostly used 35-mm film (also called 135 film according to ISO Standard 1007), where the image size on the film is typically 36 mm × 24 mm. (The width of the film spool is 35 mm, somewhat larger than 24 mm, as the picture does not extend to the edges of the spool.) A standard objective then has a focal length of 50 mm. However, modern digital cameras (particularly the more compact ones) often contain image sensors which are smaller than 36 mm × 24 mm, so that an objective lens with a correspondingly smaller focal length (e.g. 32 mm instead of 50 mm) is required for obtaining the same field of view. As many photographers are still used to the previously valid relation between focal length and angle of view, it has become common to specify the effective focal length of an objective of a digital camera as that focal length which would give the same angle of view in combination with ordinary 35-mm film. For example, an objective with a true focal length of 32 mm may then be said to have an effective focal length of 50 mm and thus function as a standard objective, rather than e.g. a macro or tele objective.

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Unfortunately, the terms are also used differently by other authors. For example, it happens that a focal distance is assumed to be the same as a focal length. Therefore, some product catalogs specify focal lengths, which should actually be called focal distances, and in addition the effective focal length.

Edmund Optics offers the world’s largest inventory of off-the-shelf optical components, which includes an extensive selection of stock optical lenses such as achromatic lenses or aspheric lenses. Many of Edmund Optics’ lenses are offered with a variety of coating options for the ultraviolet (UV), visible, or infrared (IR) spectrum.

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The following equation allows one to calculate the dioptric power and thus the focal length of lens made of a material with refractive index <$n$> and with curvature radii <$R_1$> and <$R_2$> on the two surfaces:

Prime lenses are usually more compact and lighter than zoom lenses, making them convenient for travel and long shooting sessions. Their smaller size and weight are due to the absence of the extra glass and mechanics needed for zooming.

For some applications, in particular for focusing of imaging systems, it is essential than the focal length of an optical system can be fine adjusted. The following physical principles can be used:

A wide-angle lens is often characterized by a focal length of 35mm or shorter, giving the photographer a wide field of view. The wider your field of view, the more of the scene you'll effortlessly capture in the frame. These lenses are ideal for many scenarios, and most photographers have at least one trusty wide-angle lens in their kit. If you’re a beginner photographer or want the first lens for a camera camera, it’s wise to go with a nifty 35mm lens focal length.

Focal lengthcamera

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Note that the lens equation applies for rays, assuming that the paraxial approximation is valid, i.e., all angles relative to the beam axis remain small.

EKSMA Optics offers standard plano-convex, plano-concave, biconvex, biconcave, cylindrical lenses and lens kits made of BK7, UVFS or CaF2 optical materials. EKSMA Optics also has an extensive experience in manufacturing of custom optical lenses from a variety of other optical materials. Lenses of custom design can be produced in our CNC lens polishing facility and later coated for your application.

Then there's the standard lens, around 50mm, often hailed as the "nifty fifty." It’s akin to the human eye in how it captures the world, making it incredibly versatile. It’s perfect for everyday shooting and portraits, blending background and foreground elements naturally. As a beginner, using a 50mm lens encourages you to physically move around, engaging more with your environment, which can lead to more thoughtful compositions.

where it is assumed that the beam radius at the focus is much smaller than the initial beam radius <$w_0$>. (This condition is violated for beams with a too small incident radius; the focus is then larger than according to the given equation.) Also, it is assumed that the beam radius is significantly larger than the wavelength <$\lambda$>, so that the paraxial approximation is valid.

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Considerable confusion arises from the fact that in the context of photo cameras the term effective focal length is also used with an entirely different meaning, as explained in the following.

We offer precision optics lenses from 0.5 mm to 500 mm diameter. Surface quality can reach λ/10. All optical materials available.

While there is a broad range of pricing for prime lenses, they can be less expensive than zoom lenses of comparable quality, especially at wider apertures. This cost-effectiveness stems from the more straightforward construction and fewer materials required.

focallength中文

One may eliminate chromatic aberrations altogether by using optical systems with mirrors only. A curved mirror with radius of curvature <$R$> has a focal length <$f = R / 2$> (for normal incidence), determined only by the geometry and thus independent of the wavelength. On the other hand, for non-normal incidence the focal length in the tangential direction is decreased by the cosine of the angle of incidence, and increased by the inverse cosine of that angle in the sagittal direction. Therefore, such mirrors can introduce astigmatism.

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A mirror with a curvature radius <$R$> of the surface has a focal length <$f = R / 2$>, if the beam axis is normal to the mirror surface. (We take positive signs for concave curvatures and focusing mirrors.) If there is some non-zero angle <$\theta$> between the beam axis and the normal direction, the focal length is <$f_{\tan} = (R / 2) \cdot \cos \theta$> in the tangential direction (i.e., within the plane of incidence) and <$f_{sag} = (R / 2) / \cos \theta$> in the sagittal direction.

The differences between cropped (APS-C) and full-frame sensors are significant in digital photography, influencing various aspects of image quality, field of view, depth of field, and camera system size and cost.

With ten years under my belt as a professional photographer, I've found that telephotos are better than wide for my work — here's why.

focallength是什么

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Getting into the art of photography? Just upgraded to a new camera body and need to decide which lens to purchase? Finding the right lens for your needs depends entirely on the focal length. Are you shooting portraits, weddings, sports, or wildlife? Street? Food?

If the lens marking is unclear or you want more details, the lens manual or the manufacturer's website will provide specifications, including the focal length.

Lens compatibility is another consideration; full-frame lenses can be used on both sensor types, but APS-C lenses on full-frame bodies may result in vignetting. Finally, while full-frame cameras are more expensive, they are preferred for their superior image quality and flexibility in various shooting conditions. Conversely, due to the crop factor, APS-C cameras are favored for their affordability, compactness, and built-in telephoto advantage, making them a versatile choice for many photographers.

The explained definition delivers a focal length which can also be used in equations for the size of the focus (see below), for example.

Different sign conventions for focal lengths are used in the literature. For example, one may have a negative front focal length if the front focal point lies before the front principal plane. Obviously, any equations involving focal lengths should be used with the assumed sign conventions.

If a collimated Gaussian beam with beam radius <$w_0$> hits a focusing lens with focal length <$f$>, the beam radius of the beam waist (focus) after the lens can be calculated with the equation

Focal length in photography refers to the distance between the lens and the image sensor when the lens is focused on infinity. It's typically measured in millimeters (mm) and is a key determinant of a lens's angle of view — the extent of the scene captured by the lens — and its magnification.

The formula ignores the constant part of the optical phase change as well as optical aberrations. Note that depending on the function of the lens – for example, focusing collimated input beams or refocusing divergent light –, higher-order terms in the phase profile may be required to avoid optical aberrations.

Our spherical lenses are widely used in a variety of industrial and detection cameras, microscopic objectives, spectral imaging, machine vision, infrared night vision and sensing, thermal imaging, environmental protection and biology. Lenses can be equipped with anti-reflective coatings, HR coatings and metallic mirror coatings, dielectric films and spectroscopic films.

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A common (but not universally used) approach for the definition of focal lengths of extended systems is based on geometrical optics. For finding the front focal point, one calculates rays which are horizontal on the back side (see Figure 2), using the paraxial approximation. The optical system is considered as a “black box”, where one does not care about the actual ray paths; instead, one works with internal rays which are extrapolated from the outer rays. Based on those extrapolated rays, one can define the front principal plane (or first principal plane). The front focal length is then the distance between the front focal point (in the front focal plane) and the front principal plane (see Figure 2). Some authors define the focal length to be negative in the situation of Figure 2 because the focal point is located before the front principal plane; others take the absolute value.

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DPM Photonics offers precision lenses for collimating the output of high power fiber devices. We also sell focusing objective lenses.

For an optical system, which may consist of multiple lenses and other optical elements, the above definition of the focal length cannot be used, as it is not clear a priori for an extended system where to measure the distance to the focus: from the entrance into the optical system, from the exit, the middle, or some other position? In principle, an arbitrary definition of a reference point (e.g. the entrance or the middle) could be used, but that would in general mean that some common rules can not be applied, which e.g. hold for the radius of the beam waist at a focus behind some lens with a given focal length (see below), or the possible magnification of a telescope containing that optical system.

Any 24mm and 16mm lens is an excellent option if you want something extra wide. Focal lengths below 16mm are considered ultra-wide angles.

OPTOMAN's AR-coated lenses are optimized for high laser power applications. These lenses can be used for intracavity, multi-kW CW, and ultrafast pulse applications. Sputtered anti-reflective coatings feature reflectance per surface down to R < 0.01%.

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Capture distant subjects while keeping your camera lightweight with the FE 70-200mm f/4 G OSS Lens from Sony. This full-frame lens is designed for use with mirrorless E-mount cameras where it delivers...

Knight Optical has an extensive lens portfolio which are suitable for a variety of applications. Our stock lenses included aspheric, achromatic doublet, ball & half ball, biconvex, cylindrical, condenser, Fresnel, planoconcave/convex, plastic and rod lenses. Knight Optical also offers custom lenses if our stock optics do not meet our customer’s requirements.

Ecoptik produces a wide range of spherical lenses of different types (including meniscus lenses, half ball lenses, custom hyper-hemisphere lenses and achromatic lenses). We are happy to produce custom lenses of many types.

Let’s break it down: Wide-angle lenses (under 35mm) are your go-to for capturing vast landscapes and bustling street scenes. They fit more into the frame, which is great for sweeping views and architectural photography. Meanwhile, telephoto lenses (over 70mm) excel in bringing distant subjects into sharp relief. They're ideal for zeroing in on distant details, perfect for sports or wildlife photography, and they add a dramatic flair by compressing space, making elements in the photo appear closer together.

Long-focal length lenses range in the 100-600+ range and appear to bring far away objects close to the camera. Made swimmingly for the landscape photographers in mind, long lengths are perfect for wildlife, the bird on the backyard feeder, the child at the top of a water slide, or athletes on the other side of the football field. Lenses longer than 70mm focus on infinity after 100 feet. This infinity-focusing distance means a couple of different things.

They typically have larger maximum apertures (e.g., f/1.4, f/1.8, f/2.8), allowing more light to reach the sensor. This makes them excellent for low-light situations and for achieving shallow depth-of-field effects where the subject is in sharp focus against a smoothly blurred background.

In contrast to focal lengths, focal distances are related not to the principal planes but rather to the vertex points of lenses (not caring about a housing, which may be further extended). The front focal distance is thus the distance between front focal point and the entrance surface of the optics, while the back focal distance is the distance between the back surface and the back focal point.

Curved laser mirrors usually have a curvature radius somewhere between 10 mm and 5 m. The fabrication of dielectric mirror coatings can be more difficult for very strongly curved mirror substrates, but with refined techniques it is possible to reach focal lengths of only a few millimeters, as required for some miniature lasers.

The most popular wide-angle zoom range is 16-35mm. Most kit or standard zoom lenses go down to 24mm or28mm. The widest lenses on the market are 10mm (rectilinear) and 8mm (fisheye).

PPD manufactures custom, high precision optical components including spherical lenses, lens assemblies and spherical mirror substrates for imaging, machine vision and high energy laser applications from the ultraviolet (UV) through the near-infrared (NIR). Coated and uncoated optics are available from 2 mm to 8” in diameter and in a wide range of materials including fused silica, infrasil, N-BK7, YAG, SF11 and other high index glasses. If your radius of curvature is not yet determined, contact us for information on existing fabrication tooling and test plates, or send us your design specifications for a fully custom lens or mirror quotation.

For a defocusing system, the front focal plane can be located on the output side; it contains a virtual focal point. Again, the focal length is the distance between principal plane and focal plane.

Similarly, one can define the back focal plane (or second focal plane) and back principal plane (or second principal plane), where horizontal rays occur on the left side, while on the right side one has converging rays for a focusing system and diverging rays for a defocusing system. If the refractive index is the same on the input and output side (e.g. ≈1 for air), the front focal length and back focal length are identical (apart from possible sign differences used by some authors) and can thus simply called the focal length. The two principal planes, however, generally do not coincide for thick lenses, and they can even lie outside a lens.

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On the other hand, the smaller APS-C sensors come with a "crop factor" of about 1.5x to 1.6x, effectively increasing the focal length of lenses and providing extra "reach," which can be beneficial for telephoto photography such as sports or wildlife. Despite potentially higher noise levels in low light, APS-C cameras offer a more compact and affordable option for those seeking a balance between performance and portability. This makes them attractive to amateurs, enthusiasts, and even professionals who value a lighter system.

The curvature radii are taken as positive values for convex surfaces and negative for concave surfaces. Positive results are obtained for focusing lenses, negative results for defocusing lenses. The last term is relevant only for thick lenses with substantial curvature on both sides. The formula delivers the focal length within the paraxial approximation, not considering spherical aberrations, for example.

Remember that all focal lengths depend entirely on the photographer’s vision or personal preference. Like all art forms, there are no steadfast rules to abide by. This article is merely a guideline for the purpose of each focal length, including some technical differences between the various offerings you see today.

Ordinary lenses, working on the basis of refraction, have a focal length which is slightly wavelength-dependent due to the wavelength dependence of the refractive index (–> chromatic dispersion). This effect leads to chromatic aberrations of imaging systems and similar problems in other applications where an optical system is used for a wide range of optical wavelengths. Lens combinations (e.g., objectives for photographic cameras) can be designed such that chromatic aberrations are minimized. Most common is the use of achromatic doublets, i.e., lenses consisting of two different glass materials chosen such that the overall chromatic aberrations are largely canceled.

Lastly, fisheye lens are a super fun addition to the camera bag if you’re into the widest view possible. Their angle of view is usually 180°, allowing you to see half of a full rotation and offering a distinctive, hemispherical lens distortion. They cram in as much information as possible; thus, they don’t produce straight lines. These are awesome for creative, experimental photography projects, especially within fashion portraits or skateboarding content.

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Additionally, the larger size of full-frame sensors allows for better low-light performance and less noise at high ISO settings, enhancing image quality in challenging lighting conditions.

Avantier is proficient in producing customized lenses for all kinds of applications, ranging from prototyping to large-scale production.

Human eyesfocal length

where <$a$> is the distance from the original focus to the lens. This shows that <$b \approx f$> if <$a \gg f$>, but <$b > f$> otherwise. That relation can be intuitively understood: a focusing power <$1 / a$> would be required to collimate the incident beam (i.e. to remove its beam divergence), so that only a focusing power <$1 / f - 1 / a$> is left for focusing.

Generally, choosing a long focal length lens, like 70mm, 135mm, or 200mm, is wise to isolate textures and distant features to create dramatic backgrounds. Wide focal length lenses, like 16mm, 24mm, or 35mm, thrive when you want the entire scene in focus, like when shooting simple landscapes with long leading lines.

Focaldistance vsfocal length

Wide-angle camera lenses are a fan-favorite among most lifestyle bloggers and everyday shooters; they’re perfect for capturing an entire scene and confined spaces if you want to show how the entire bedroom looks or the whole restaurant with the crowds of customers — the shorter focal length lens will be your best bet.

A lens focal length combines various elements that help to focus the light and minimize distortions. The location where all the light rays converge to form a sharp image is known as the optical center of the lens.

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Low-loss ion-beam-sputtered anti-reflection (AR) coatings with reflectivity less than 0.1% per surface and low-absorption high reflector mirror coatings are available on PPD lenses or can be applied to customer supplied substrates. PPD uses only IBS thin film deposition technology because it is a repeatable process which results in coatings that are durable, stable and easy to clean.

Focal length

Focal length might sound technical, but it's really your secret weapon in framing the perfect shot. It's measured in millimeters and determines not just the angle of view—how much of your scene is captured—but also how your images are magnified. As a beginner, understanding this can transform the way you approach photography.

The focal distance should also not be confused with the working distance, which is the distance between a specimen and the lens housing. Note that a specimen is not necessarily placed in the focal plane, e.g. when the input light to an objective is not collimated.

Beyond the technical benefits, using a prime lens influences your creative process. Without the ability to zoom, you’re encouraged to physically move around your subject to compose the perfect shot. This often results in more thoughtful framing and a better connection with your subject. Whether you’re shooting portraits, street scenes, or landscapes, a prime lens can push you to explore new perspectives and enhance your compositional skills.

Laserton offers various types of lenses, including plano-convex, plano-concave, double convex, double concave, meniscus, ball, achromatic and cylindrical lenses.

The simplest way to find the focal length of a lens is to look at its specifications. Most lenses have the focal length marked directly on them. For prime lenses, it will be a single number (e.g., 50mm), while zoom lenses will show a range (e.g., 24-70mm).

Artifex Engineering offers customised optical lenses such as achromatic or cylindrical lenses for almost any application in the UV to IR spectrum. Special requirements such as segmenting and black painted edges can be made on request. Visit our product page for more information. We look forward to your inquiry.