Affecting DOF are camera-to-subject distance, lens focal length, selected lens f-number, format size, and circle of confusion criterion.

The combination of focal length, subject distance, and format size defines magnification at the film / sensor plane.

For a given f-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF ; decreasing magnification increases DOF.

If, for the same focal length setting, the subject distance is adjusted to provide the same field of view at the subject, at the same f-number and final-image size, the smaller format has greater DOF, as with the “ same picture ” comparison above.

If pictures are taken from the same distance using the same f-number, same focal length, and the final images are the same size, the smaller format has less DOF.

If pictures taken from the same subject distance using the same focal length, are given the same enlargement, both final images will have the same DOF.

where λ is the wavelength of the light and N is the f-number ( focal length divided by diameter ) of the imaging optics.

In film, an insert is a shot of part of a scene as filmed from a different angle and / or focal length from the master shot.

Its design enabled construction of lenses of large size and short focal length without the weight and volume of material in conventional lens designs.

Similarly to curved mirrors, thin lenses follow a simple equation that determines the location of the images given a particular focal length () and object distance ():

The focal length f is considered negative for concave lenses.

Incoming parallel rays are focused by a convex lens into an inverted real image one focal length from the lens, on the far side of the lens.

With concave lenses, incoming parallel rays diverge after going through the lens, in such a way that they seem to have originated at an upright virtual image one focal length from the lens, on the same side of the lens that the parallel rays are approaching on.

Rays from an object at finite distance are associated with a virtual image that is closer to the lens than the focal length, and on the same side of the lens as the object.

Images of black letters in a thin convex lens of focal length f are shown in red.

Note that this equals the perpendicular distance from the focus to the directrix, and is twice the focal length, which is the distance from the focus to the vertex of the parabola.

If a point X is located on a parabola which has focal length and if is the perpendicular distance from X to the axis of symmetry of the parabola, then the lengths of arcs of the parabola which terminate at X can be calculated from and as follows, assuming they are all expressed in the same units.

It is measured in dioptres ( inverse metres ), and equals the inverse of the focal length of the optical device.

" Most of his movies are shot almost entirely with rectilinear ultra wide angle lenses of 28 mm focal length or less in order to achieve a distinctive signature style defined by extreme perspective distortion and extremely deep focus.

" This attitude markedly differs from the common definition in photography which qualifies 40mm to 65mm as the focal length of a normal lens instead due to resembling natural human field of view, unlike Gilliam's signature style defined by extreme perspective distortion due to his usual choice of focal length.

The largest and most famous of these was a reflecting telescope with a primary mirror and a 40-foot ( 12 m ) focal length.

If the beam has been collimated using a lens or other focusing element, the divergence expected can be calculated from two parameters: the diameter,, of the narrowest point on the beam before the lens, and the focal length of the lens,.

In general, the focal length or EFL is the value that describes the ability of the optical system to focus light, and is the value used to calculate the magnification of the system.

( ad 2 ) – The power density in the spot of incidence of the beam with the “ workpiece ” depends on more factors, like the size of electron source on the cathode, “ optical quality ” of the accelerating electric lens and the focusing magnetic lens, alignment of the beam, on the value of the accelerating voltage, and on the focal length.

A radio noise source is a device that emits radio waves at a certain frequency, used to calibrate radio telescopes such that received data may be compared to a known value, as well as to find the focal point of a telescope soon after construction, so that the wave guide and front end may be properly located.

The value computed according to the first definition exceeds that from the second by just one focal length.

Their focal range is about 1000 times their aperture diameter, so it makes sense as a hyperfocal distance with CoC value of f / 1000, or image format diagonal times 1 / 1000 assuming the lens is a “ normal ” lens.

( Caution: In this context, the focal length value differs with each film gauge and CCD size for optical reasons, but the angle of view is the same for any of them, so it's easier comparing the angle of view with lenses for different formats than their focal lengths.

This means the lens's F-number value is fixed to the overall designed focal ratio of the optical system ( the diameter of the primary mirror divided into the focal length ).

The strategy ’ s focal areas are divided into two dimensions: Under the headline “ more value ”, the company focuses on the areas “ social progress ”, “ safety and health ” and “ performance ”.

Recognition of these variants may have prognostic value in individuals with primary focal segmental glomerulosclerosis ( i. e. where no underlying cause is identified ).

The basic question asked by the V in the VRIO framework for internal analysis is “ Is this resource or capability valuable to the focal firm ?” In this case, the definition of value is whether or not the resource or capability works to exploit an opportunity or mitigate a threat in the marketplace.

Respecting their need, one of the major focal points of our concern is the South-Asian region.

Each one of these is, by its nature, a focal point or a point of natural congestion.

The focal point of the park is the main terrace, surrounded by a long bench in the form of a sea serpent.

On 4 March 2008, in announcing a partnership with Magna Steyr to outsource manufacture of over 2, 000 cars annually at Graz, Austria, the company stated " The continuing growth and success of the company is based upon Gaydon as the focal point and heart of the business, with the design and engineering of all Aston Martin products continuing to be carried out there.

Whereas consequentialist theories posit that consequences of action should be the primary focus of our thinking about ethics, virtue ethics insists that it is the character rather than the consequences of actions that should be the focal point.

The Secretariat of the Convention on Biological Diversity is the focal point for the International Year of Biodiversity.

For Christadelphians, this is the focal point of the gospel taught by Jesus and the apostles.

Apart from being the focus of the country's literature and theatre, Dublin is also the focal point for much of Irish Art and the Irish artistic scene.

Especially noteworthy is Matthew Tindal's Christianity as Old as the Creation ( 1730 ), which " became, very soon after its publication, the focal center of the deist controversy.

Paradoxically, it is possible to reduce the divergence of a laser beam by first expanding it with one convex lens, and then collimating it with a second convex lens whose focal point is coincident with that of the first lens.

The light is not focused to a point but forms an Airy disk having a central spot in the focal plane with radius to first null of

The distance a < nowiki ></ nowiki > e from a focal point to the centre is called the linear eccentricity of the ellipse ( f = a < nowiki ></ nowiki > e ).

( where again a and b are one-half of the ellipse's major and minor axes respectively, and f is the focal distance ) or, as expressed in terms using the flattening factor

This is demonstrated by earthquake focal mechanisms.

Seizure types are organized firstly according to whether the source of the seizure within the brain is localized ( partial or focal onset seizures ) or distributed ( generalized seizures ).

Symptomatic epilepsies arise from the effects of an epileptic lesion, whether that lesion is focal, such as a tumor, or a defect in metabolism causing widespread injury to the brain.

What can be even more confusing is that certain syndromes, such as West syndrome, featuring seizures such as infantile spasms, can be classified as idiopathic, syndromic, or cryptogenic depending on cause and can arise from both focal or generalized epileptic lesions.

Epilepsy surgery is an option for people with focal seizures that remain resistant to treatment.

In 1961, Jerry Bails ' Alter Ego, devoted to costumed heroes, became a focal point for superhero comics fandom and is thus sometimes mistakenly cited as the first comics fanzine.

In 1951, he summed up his vision as follows: " If the camera is to make a contribution at all to dance, this must be the focal point of its contribution ; the fluid background, giving each spectator an undistorted and altogether similar view of dancer and background.

Surgical removal of the overactive part of the pancreas is curative with minimal risk when hyperinsulinism is focal or due to a benign insulin-producing tumor of the pancreas.