Getting up close to birds and other wildlife requires a special type of telephoto lens: a super telephoto lens. You may want to combine it with an extender for even further reach.

For any giv­en cam­era, the fac­tors in deter­min­ing hyper­fo­cal dis­tance are the lens focal length and aper­ture size. Adjust­ments to the aper­ture will change the hyper­fo­cal dis­tance: a larg­er aper­ture diam­e­ter will pro­duce a hyper­fo­cal dis­tance that is far­ther out and a small­er aper­ture diam­e­ter will move the hyper­fo­cal dis­tance clos­er to the cam­era. Sim­i­lar­ly, a longer focal length will increase your hyper­fo­cal dis­tance while a short­er focal length will bring it clos­er. Since the hyper­fo­cal dis­tance describes the dis­tance to which your lens must be focused, sub­ject dis­tance isn’t a fac­tor.

Depth of fieldgithub

Due to physics, a lens with a shorter focal length has a wider angle of view, and one with a longer focal length has a narrower angle of view. And that’s how we came to use focal length to describe the angle of view of a lens!

Also see: Why Is a Super Telephoto Lens Necessary for Sports Photography? What is the difference between a 200mm and 300mm telephoto lens?

Crit­i­cal focus may only be achieved at pre­cise­ly one plane of focus. All sub­ject points that align with this plane will also be in sharp focus (assum­ing your lens does­n’t exhib­it cur­va­ture of field); any devi­a­tion from this plane results in pro­gres­sive defo­cus­ing since the light rays no longer con­verge at the focal plane. Nev­er­the­less, in prac­tice, there’s an area just ahead of and behind the plane of focus that will be ren­dered as accept­ably sharp in the pho­to­graph because the devi­a­tions from absolute con­ver­gence are too small to notice. The depth of field describes the total region sur­round­ing the plane of focus in which objects are ren­dered as accept­ably sharp accord­ing to the sub­jec­tive stan­dards estab­lished for a par­tic­u­lar pho­to­graph.

Learn composition techniques that leverage on the characteristics of different lenses in: Professional Composition Techniques (3): Making Good Use of Lenses

A longer focal length… - Captures less of the scene (= has a narrower angle of view) - Makes distant objects appear bigger (= has a higher magnification)

Telephoto lenses provide an angle of view that is much narrower than human vision. 70-200mm lenses provide the classic telephoto focal range.

Pho­tog­ra­phers exploit the depth of field all of the time to achieve effects such as deep or shal­low focus. Deep focus pho­tog­ra­phy relies on a con­sid­er­able depth of field to achieve accept­able sharp­ness in the fore­ground, mid­dle-ground, and back­ground of the pic­ture. This effect is often asso­ci­at­ed with land­scape pho­tog­ra­phy (where much of the image appears in sharp focus) and some forms of street pho­tog­ra­phy. Shal­low focus pho­tog­ra­phy fea­tures a nar­row or small depth of field, which is char­ac­ter­ized by a sharply focused sub­ject and an out of focus, or blurred, back­ground and fore­ground. This tech­nique is fre­quent­ly used by por­trait photographers—especially those work­ing on loca­tion as opposed to in studio—because it visu­al­ly sep­a­rates the sub­ject from the scene. Bokeh describes the aes­thet­ic qual­i­ty and char­ac­ter of how lens­es ren­der the out of focus ele­ments in a pic­ture.

Light from any point in object space emerges from the rear ele­ment of a lens as a cone. When a sub­ject point is in focus, the apex of its light cone coin­cides with the focal plane, which forms an image point in the pho­to­graph. If the sub­ject point does­n’t come into per­fect focus on the image sen­sor, it cre­ates a small blurred cir­cle called a cir­cle of con­fu­sion. The three fac­tors that con­trol the depth of field—the aper­ture, focal length, and sub­ject distance—do so by vary­ing the size of the blur cir­cles. The diam­e­ter of the cir­cle of con­fu­sion with the res­o­lu­tion of the image sen­sor is used to cal­cu­late the depth of field.

In pho­tog­ra­phy, space ahead of a lens is known as object space, while space behind is called the image space. In the­o­ry, rays of light from any point in object space should con­verge, or focus, at some point behind the lens. As the dis­tance between the lens and sub­ject changes, the dis­tance behind the lens at which the sub­ject is focused also changes. A sub­ject far­ther from the cam­era will focus clos­er behind the lens than a near­by sub­ject. [This is why macro lens­es are capa­ble of such a long exten­sion: to bring very close objects into focus.]

Depth of fieldsimulator

Sub­ject dis­tance. As the sub­ject (on which you’re focused) moves pro­gres­sive­ly clos­er to the cam­era, the depth of field decreas­es.

depth offield中文

In prac­tice, pho­tog­ra­phy is a two-dimen­sion­al medi­um that projects light onto a flat image sen­sor for record­ing. The posi­tion of the image sensor’s sur­face deter­mines the focal plane. When rays of light from a sub­ject point con­verge to a point on the focal plane, they’re con­sid­ered in focus. A sub­ject point that’s in focus is sit­u­at­ed along an imag­i­nary two-dimen­sion­al plane, known as the plane of focus, which rep­re­sents the the­o­ret­i­cal plane of crit­i­cal focus. [The plane of focus is par­al­lel to the image sen­sor and per­pen­dic­u­lar to the opti­cal axis.] Focus­ing the lens adjusts its dis­tance to the image sen­sor and shifts the plane of focus either toward or away from the cam­era in object space.

Depending on the scene and your intentions, you might not need to go ultra-wide to frame what you want to show perfectly.

When you look straight ahead with your bare eyes, the field of view in focus is around 50° to 60°. Wide-angle lenses are any lens that gives a field of view wider than that. Ultra-wide-angle lenses are a special kind of wide-angle lens.

Light entering the lens converges (crosses) on its way to the image sensor. This convergence point is known as the optical centre of the lens and has the sharpest focus. The focal length is the distance between this convergence point and the image sensor.

Telecentriclens

Shallowdepth of field

At 16mm, we can capture the entire façade of the fire station as well as the road and the hedge in the foreground. As the focal length increases, details appear bigger in the frame while more of the foreground and the building is cropped out. 200mm gives us a good close-up of the building name and the crests below it.

Notice how the buildings don’t appear to converge towards the top. They would on a wide-angle lens due to perspective exaggeration.

Learn the best ways to create amazing images and videos, share your works with the community and be inspired by our community.

Aper­ture. An essen­tial prop­er­ty of all lens­es is that chang­ing the aperture’s diam­e­ter when adjust­ing expo­sure also affects the depth of field. Increas­ing the aper­ture diam­e­ter results in less depth of field and decreas­ing the aper­ture diam­e­ter results in more depth of field. Keep in mind that effects of dif­frac­tion still apply, and it may not be prac­ti­cal to use the small­est aper­ture diam­e­ter pos­si­ble in all sit­u­a­tions (see Reci­procity Law).

Depth of field

Lenses are classified as wide-angle, standard, or telephoto depending on their focal lengths. Ultra-wide-angle lenses are a subset of wide-angle lenses, whereas medium telephoto and super telephoto lenses are subsets of telephoto lenses.

The hyper­fo­cal dis­tance is the clos­est focus dis­tance at which the depth of  field’s far lim­it of accept­able sharp­ness aligns with infin­i­ty. When a lens is focused to the hyper­fo­cal dis­tance, its near lim­it of accept­able sharp­ness will reside at half that dis­tance to the cam­era. If your lens has the depth of field scale, the sim­plest method for focus­ing to the hyper­fo­cal dis­tance is by rotat­ing the focus ring until the line cor­re­spond­ing to your f‑stop’s far lim­it of accept­able sharp­ness aligns with the infin­i­ty mark.

Learn more about how to make the most of wide-angle lenses in: Exploring Wide Angle Lenses Part 1: Photo Effects of Wide-Angle Lenses 24mm Closeups: 3 Simple Exercises for Mastering Wide-Angle Perspective

Any focal length above 135mm full-frame equivalent is considered telephoto. However, 70 to 135mm (full-frame equivalent) is considered short or medium telephoto. These are popular for portrait and product photography due to their natural perspective and comfortable working distance for close-up shots.

Focal length. Lens focal length is a sig­nif­i­cant fac­tor in man­ag­ing the depth of field. Short focal length lens­es pro­duce greater depth of field, while long focal length lens­es pro­duce shal­low depth of field.

Depth of fieldcalculator

The focal length also affects many other aspects of your image, such as perspective and depth of field. To find out more,  see 4 Lens Concepts to Revolutionise Your Photos.

Some lens­es have a depth of field scale print­ed direct­ly on their bar­rels or under a trans­par­ent plas­tic win­dow. The depth of field scale con­sists of sev­er­al pairs of num­bers on either side of the dis­tance index, with each pair rep­re­sent­ing an f‑stop of cor­re­spond­ing val­ue. When the aper­ture is set to one of the f‑stops indi­cat­ed on the scale, the range on the dis­tance scale that lies between this pair is con­sid­ered the depth of field. The f‑stop lines on the far side of the focus index rep­re­sent the far lim­its of accept­able focus and the lines on the near side of the focus index rep­re­sent the near lim­its of accept­able focus.

Learn the best ways to create amazing images and videos, share your works with the community and be inspired by our community.

This focal length is measured when the lens is focused to infinity (far into the distance). This is because when the lens is focused to infinity, light rays enter the lens almost parallel. When focused on a nearby subject, they enter the lens at an angle.

We usually describe a lens by its focal length. What does it refer to and how does it affect your images? Find out in this article.

You need a very long focal length to capture a detailed close-up picture of the moon without cropping. The image above was captured at 1600mm using an 800mm lens and a 2x extender.

A standard or “normal” lens gives a perspective that is very close to that of human vision. Most kit lenses are standard zoom lenses. The popular RF50mm f/1.8 STM “nifty fifty” lens is a standard lens on a full-frame camera, whereas the RF28mm f/2.8 STM is a slightly wider standard lens on an APS-C camera.

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When picking a lens, one of the first things you must decide on is the focal length or focal range that you want. This is because the focal length describes the angle of view, i.e., it tells how much of the scene in front of you the lens can capture.

FOVand focal length

Ultra-wide-angle lenses take in so much that they are perfect for capturing grand scenes and large objects that are right in front of you, especially in tight spaces where you cannot move further back.

It’s impor­tant to under­stand that the depth of field is a the­o­ret­i­cal cal­cu­la­tion that does­n’t take into account lens aber­ra­tions, light dif­frac­tion, and post-cap­ture manip­u­la­tions such as sharp­en­ing and crop­ping.

Let’s look at what happens when we shoot at different focal lengths from the same position. Note: For ease of illustration, the angles shown in this article are the horizontal angle of view.

The depth of field is com­mon­ly expressed using units of length. The sub­ject dis­tance is mea­sured from the focal plane of the cam­era (whose posi­tion is indi­cat­ed on top of your cam­era with the focal plane indi­ca­tor, ɸ) to the point in object space on which the lens is focused. The total depth of field is the entire range of accept­able focus. it’s mea­sured from the near lim­it of accept­able focus, which lies between the cam­era and sub­ject, and the far lim­it of accept­able focus, which lies between the sub­ject and infin­i­ty.

There’s no tru­ly objec­tive mea­sure for what qual­i­fies as an accept­able degree of sharp­ness con­cern­ing the depth of field. A pho­to­graph that looks ade­quate­ly sharp when enlarged to fit a 15-inch note­book dis­play may appear slight­ly unsharp when expand­ed to a 30-inch desk­top dis­play. A 24×36 inch print may look sharp from across the room, less sharp from a com­fort­able read­ing dis­tance, and down­right blur­ry from the tip of your nose.

Learn more about what you can do with a standard lens in: Standard Lens Techniques: Using the Point of View to Draw the Viewer In 50mm Portraits, My Style: Creating A Picture of a Memory

Ultra-wide-angle lenses exaggerate perspective so distances between objects look bigger. When combined with the wide field of view, it can bring out a sense of space.

A shorter focal length… - Captures more of the scene (= has a wider angle of view) - Makes distant objects appear smaller (= has lower magnification)