Focal length of the lens

Focal length of the lens Is one of the most important lens parameters. The focal length of a lens indicates how far or close (wide) the lens can 'see'.

Focal length of the lens

Focal length of lenses - article from Radozhiva

Focal length is measured in millimeters, centimeters and meters. For example, the designation of the fixed lens Nikon 85mm F / 1.8D AF Nikkor says that his focal length is fixed and is 85 millimeters. A designation Tamron 28-200mm 1: 3.8-5.6 Macro AF Aspherical XR (IF) A03 suggests that the focal length of the lens can vary from 28 millimeters to 200 millimeters. Lenses in which the focal length can vary are called zoom lens (zoom lens, zoom lens). Zoom ratio is calculatedI am dividing a larger number by a smaller one, in this example 200mm \ 28mm = 7 times.

Usually, the larger the focal length of the lens, the larger the size of the lens itself, especially its length.

Focal length Is the first thing to look for when choosing a lens. It shows what angle of view the camera will capture when working with one or another lens.

Attention: the focal length of the lens is the physical size of the lens itself, it does not change and does not depend on the type of cameraon which the lens is used. But for cropped cameras and for cameras with different physical matrix sizes, the parameter EGF (Equivalent focal length), it shows the real viewing angle for a 35mm film, which is obtained when using one lens or another on cameras with different matrix sizes. More details in the section crop factor.

Here is an example of how the space that the camera can cover when using lenses with different focal lengths changes.

17mm

Focal Length 17mm

Focal Length 17mm

24mm

Focal Length 24mm

Focal Length 24mm

35mm

Focal Length 35mm

Focal Length 35mm

50mm

Focal Length 50mm

Focal Length 50mm

70mm

Focal Length 70mm

Focal Length 70mm

85mm

Focal Length 85mm

Focal Length 85mm

100mm

Focal Length 100mm

Focal Length 100mm

135mm

Focal Length 135mm

Focal Length 135mm

200mm

Focal Length 200mm

Focal Length 200mm

300mm

Focal Length 300mm

Focal Length 300mm

For examples, I used a camera Nikon D200mounted on a tripod. All photos were taken at F / 5.6, the following lenses were used:

It is often said that the photographer should have a set of lenses that covers the desired range of focal lengths and thus covers all possible situations in the work of the photographer. One of the most classic sets for full-frame cameras can be considered: 14-24mm, 24-70mm, 70-200mm, 200-400mm. For cropped cameras, usually a good set consists of 11-16mm, 16-50mm, 50-135mm lenses. Covering the entire range of focal lengths is not worth chasing; you can safely do without a single fixed lens. The division into different types of lenses can be found here.

In addition to the angle (field) of view, the focal length affects the perspective of the image (due to the difference in distance to the subject with equal proportions of the subject). At different focal lengths, the sizes of objects are correlated differently in photographs. Long-focus lenses bring closer not only the subject itself, but also the entire space behind the subject and in front of the focus subject. And wide-angle lenses average the sizes of all elements in photographs. Also, different focal lengths affect to blur the background.

17 mm

Aspect ratio at 17mm

Aspect ratio at 17mm

24 mm

Aspect ratio at 24mm

Aspect ratio at 24mm

35 mm

Aspect ratio at 35mm

Aspect ratio at 35mm

50 mm

Aspect ratio at 50mm

Aspect ratio at 50mm

70 mm

Aspect ratio at 70 mm

Aspect ratio at 70 mm

85 mm

Aspect ratio at 85 mm

Aspect ratio at 85 mm

100 mm

Aspect ratio at 100 mm

Aspect ratio at 100 mm

135 mm

Aspect ratio at 135 mm

Aspect ratio at 135 mm

200mm (195)

Aspect ratio at 195 mm

Aspect ratio at 195 mm

300 mm

Aspect ratio at 300 mm

Aspect ratio at 300 mm

Personal experience:

I do not like to convert the focal length from millimeters to degrees of field of view, who is interested, then there is an article on Radozhiv 'Relationship between focal length, viewing angle, and focus distance'. In practice, it is enough to understand what the approximate angles are given by a lens with a certain focal length in order to intuitively know how another longer or wider lens will behave on the camera. Advise experiment with the lens simulator. There is still an interesting article about dependence of the focal length of the lens on the focusing distance.

Conclusions:

The choice of a lens, first of all, entails determining the desired focal length range. Focal length indicates how wide or narrow the lens 'sees'. Focal length is very important to the blur zone of the blur zone and perspective images.

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Comments: 122, on the topic: Focal length of the lens

  • Andrei

    Super, as always! Thank you so much: -D

  • Lenin Ulyanov

    Accept my thanks too! Very grateful!

  • Alexander

    Thank you Arkady!

  • Vasil

    Tsіkava stattya, so such a little little tip for upcoming promotions, have people more precisely identified the focus of the show?

    • Arkady Shapoval

      Just to have an understanding about the viewing angles :) The watch is collectible, a gift from America.

      • Vasil

        Zrozumіlo (:

  • I saw your

    A telephoto lens does not have to be a telephoto lens. These concepts do not coincide somewhat :-)

    • Arkady Shapoval

      I agree, here the format of the light receiver also plays a role.

  • Andrei

    Arkady, your advice is very necessary. I have a Nikon 5100 with a whale 18-55 VR, you need to take pictures from a decent distance (from the rostrum of a hockey court, the distance in the approximate range to the object is 30-40 meters) ..
    I read your articles, made some conclusions, now I decided to try the tele lens.
    found a couple of budget options, help me choose, and if possible, the difference between the lenses in 2 words:
    Tamron AF 70-300mm F / 4-5.6 Di LD
    Nikon AF-S DX VR 55-200mm f / 4-5.6G VR
    Nikkor 55-200mm AF-S DX VR F / 4-5.6G IF ED
    Quantaray (Sigma) 80-200 mm F3.5-4.5 Nikon Ais

    and if it’s not difficult, say that it doesn’t work for 5100 and that it’s not worth considering from this + if you know a better solution with a minimum budget, let me know. Thank you in advance.

    • Arkady Shapoval

      Tamron AF 70-300mm f / 4-5.6 Di LD - full frame w / o stabilizer
      Nikon AF-S DX VR 55-200mm f / 4-5.6G VR and Nikkor 55-200mm AF-S DX VR F / 4-5.6G IF ED are the same lens - https://radojuva.com.ua/2011/03/obzor-nikon-55-200-dx-vr-otzuvu/
      Quantaray (Sigma) 80-200 mm F3.5-4.5 Nikon Ais is a manual focus lens

      The best solution is the native Nikon 55-200 f / 4-5.6G IF-ED AF-S DX VR Zoom-Nikkor with a stub, if a little more money, then the Nikon 55-300 f / 4-5.6G DX VR Zoom-Nikkor.

      • Andrei

        Thank you for your prompt reply. Now I would like to know what settings of aperture, shutter speed and ISO would you recommend for shooting with the 5100 camera with the Nikon 55-200 f / 4-5.6G IF-ED AF-S DX VR Zoom-Nikkor lens, which you recommended in the conditions of a hockey rink ? And this is dynamic lighting, the movement of players and a decent distance to them (20-40 meters). I would like to get minimally noisy photos at the maximum possible zoom (by the way, can you tell me the working zoom limit of this lens, if any?). I understand that I will not get exquisite photos, but to maximize the quality I need your advice on setting, at least can you tell me the ranges from which it is advisable not to go out when shooting in such conditions? + I understand that it is better from the "A" mode will repel when set up, right?

  • alik7ey

    much depends on the scene you want to see ...

  • Vladimir

    Tell me which lens is better to take on the Nikon 3100 Nikon 80-200 f / 2.8D ED AF Zoom-Nikkor
    Tamron SP AF 70-200 f / 2.8 Di LD (IF) Macro
    SIGMA AF 70-200 mm f / 2.8 APO EX DG HSM MACRO II

    • Arkady Shapoval

      Nikon 80-200 f / 2.8D ED AF Zoom-Nikkor will not work autofocus on your D3100 - I do not recommend it.
      Tamron SP AF 70-200 f / 2.8 Di LD (IF) Macro or SIGMA AF 70-200 mm f / 2.8 APO EX DG HSM MACRO II will need to look for a good one.

  • Elvira

    When shooting helios-81H and world-24 of the starry sky, the first gave a very clear picture and the second stars turned into spots, both lenses stood at infinity, and the question arose whether the lenses have such a characteristic as the maximum focusing distance at infinity. I don’t know how to correctly express it, but for example, one lens can focus on infinity at a distance of 100 meters, while another lens focuses on infinity after 20 meters?

  • Marat

    Arkady, please explain, do I understand correctly that the lens, for each focal length in mm, has an equivalent distance in meters and how can it be calculated? That is, say for a 50mm fixed lens, you can always calculate the distance (from the lens to the subject), regardless of the camera, where the subject will be in focus? Thank you in advance.

    • Arkady Shapoval

      You do not understand correctly. You are talking about the focusing distance, each lens can focus from infinity to the minimum focusing distance, it does not depend on the focal length in mm. Focal length shows the angle of the field of view.

  • Marat

    "Every lens can focus from infinity to closest focusing distance."

    Well, then, then you can calculate this minimum distance?
    and if everything can focus to infinity, then why say superzoom?

    • Arkady Shapoval

      The minimum distance is not necessary to calculate, it is indicated on each individual lens. Superzoom is needed for convenience. Focal length affects the angle of view of the lens and some additional factors, do not confuse it with the focusing distance.

  • Oleg

    Arkady is such a question when you put manual optics on pentax when you turn it on, you need to set the focal length, so if I have a lens of 135, and since on crop matrices it increases somewhere to 200, what needs to be set?

    • Arkady Shapoval

      It is necessary to set the real value of the focal length, i.e. 135mm.

  • Vitalik

    Please explain - (quote) "The focal length of the lens indicates how far, close (wide) the lens can see." For example 85mm.

  • qrus

    decided to purchase another lens in addition to the whale, there was a choice: Nikon AF-S DX NIKKOR ED 55-200mm 1: 4-5.6G or VIVITAR 70-200mm 1: 3.8G 58mm help, please, decide which one to choose? Prices from them identical, nikkora has problems with autofocus (manual only), but there is no information about vivitare (manual af)

  • Valery

    Hello. I'm a beginner and don't understand much. I have a Nikon D5100 camera, I bought it recently. A month ago. I have already taken many pictures. At home, the photos are worse than on the street. In general, the pictures are of high quality, rich and clear. I am satisfied. I am interested in the possibilities of this object. This is a standard lens included in the kit. AF-S NIKKOR 18-55mm 1: 3,5-5,6G And yet, is there a universal lens for all occasions. Capabilities. What is it called and its approximate price. You can BU. Where can you buy one. Thank you so much.

  • Valeri.

    Thank you.

  • Irina

    Hello! Tell me which lens is better whale 18-55 or 18-105. I will photograph mainly a child at home and outdoors?

    • Arkady Shapoval

      It will be better 18-105.

      • Katherine

        Arkady, tell me please, Nikon D3200 Camera KIT + 18-55VR + 55-200VR
        The lens model is written by AF-S Nikkor 18-55mm f / 3.5-5.6G VR DX, AF-S Nikkor 55-200mm f / 4-5.6 VR DX will autofocus work with these lenses ??? And are these lenses better or one 18-105. We choose simply for beautiful family photos. Tortured to choose what to buy))))

        • Arkady Shapoval

          Yes, it will work. 18-105 is more convenient, but in the general case it is better 18-55 + 55-200

  • anonym

    Thank you very much)))) You are super)

  • levani

    SW Arkady, hello. I wanted to ask why precisely a large focal length is suitable for shooting portraits? I have never done portraits and do not quite understand this. Do you have articles about portraiture? really want to learn.

    • Arkady Shapoval

      This is due to the psychological perception of the photographer by the model, that is, with the telephoto lens of the model, you do not need to poke lenses in the nose. Also, mostly telephoto lenses practically do not have distortion, that is, they do not distort the face. Also, with a telephoto lens, for a number of cases, a more interesting transmission of perspective and blurring of the background is achieved. Of course, a portrait can be shot on any lens, it all depends on the idea.

  • levani

    Thank you, very intelligible)

  • Victor

    Arkady, hello. Your website is like a handbook. I am looking for answers to most of the questions in your articles and reviews. Another question :). Since all problems with picture quality usually creep along the edges of the frame, isn’t it better to pick lenses over the entire range of focal lengths taking into account crop, but from glasses for a full frame? After all, only the central part of the lens will be involved. Or am I misunderstanding?

    • Arkady Shapoval

      You understand correctly. You can get out of this logic.

  • Nicholas

    Normal lenses with a focal length equal to the diagonal of the frame, short-focus lenses are smaller than the diagonal of the frame, and telephoto lenses with focal length are larger than the diagonal of the frame (matrix)

  • Andrei

    Hello, the 50mm lens is said to be the closest to the human eye. Do you mean “full” 50mm without crop factor? So let's say on NIKON it will be about 35mm, right? I mean, the overwhelming majority of people do not have full-frame cameras, but so much noise because of “fifty dollars” when 35mm “drives”! What does “fifty kopeck” have to do with it….

    • Anatoly

      focus on crop

  • Andrei

    Good afternoon!
    I just study the photo and its attendant, therefore, I'm sorry for the question:
    You write that “For the examples I used a Nikon D200 camera mounted on a tripod. All photos were shot at f / 5.6 using the following lenses: "
    But the list of lenses does not have F5.6, only one and all…. Did you have to enter that on any lens you shot at the maximum (large) focus value?

  • Alexander

    Good evening, Arkady !!
    Do you only advise on Nikon (s)? If so, please tell me, where can I find the same advice as your professional one?
    Yours faithfully,
    Alexander

    • Arkady Shapoval

      I do not advise. The articles provide general information on photographic equipment and techniques.

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