Telephoto Lens Focal Length Comparison

Although I have already done a focal length comparison from 12mm to 500mm focal length before, I decided to do it once again for telephoto lenses. I receive quite a few emails from our readers, asking about telephoto lenses and focal lengths, specifically whether a focal length of a lens is going to be sufficient for bird and wildlife photography. The below images should give you a pretty good idea about field of view when using particular focal lengths, from 70mm all the way to 1200mm:

70mm-400mm FoV

600mm-1200mm FoV

The above images are not cropped in post-production and represent equivalent focal lengths relative to 35mm. The longest field of view of the 1200mm shot was captured with the Nikon 200-400mm f/4.0 + TC-20E III TC @ 400mm (800mm effective) on a DX body, which is equivalent to 1200mm. The shortest focal length was captured with the Nikon 70-200mm f/2.8G VR II at 70mm.

  • Wouter

    Thank you!

    Wat was the distance between you and the birds? (preferably in meters- I’m a Metric Man :-) )


    • Nasim Mansurov

      Wouter, you are most welcome!

      Unfortunately, the subject distance information is not available in EXIF… I can only give you a rough estimate – I would say around 15 meters from me to the birds.

      • Aaron Priest

        KUSO Exif Viewer (free) can usually tell you the distance in meters for a raw file. The field is FocusDistance and is in meters. I have found KUSO and FxIF, a plugin for FireFox, to be invaluable. :-)

        • Nasim Mansurov

          Aaron, an EXIF viewer can only show the info if it is available :) The distance information is typically reported by a lens and if you are shooting with teleconverters and shooting over a certain distance, the information can fail to come through. If that happens, the camera will show a really large number or “unknown” for distance.

          • Aaron Priest

            Haha, I didn’t consider that the teleconverters might mess with that. I figured the camera would factor it in with the newer electronic ones and D/G lenses, but I guess not huh?

  • Wouter

    Close enough, thank you!


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  • Christine

    Wow, thanks! Just the info I was looking for. Can you explain what you mean by 800mm effective with a 200-400mm lens? How do you get a 1200 mm focal length with a 200-400mm lens? Thanks! I will definitely buy my telephoto lens by clicking on the B&H link on your website!

    • Raymond

      thanks, nasim.
      great comparison. i’ve been a fan for reading reviews on your website regularly.

      you can get 800mm effective from a 200-400mm lens by using TC-20E III just like nasim wrote before. TC-20E is a 2 times teleconverter combine with 400mm focal length it becomes 800mm and when 800mm lens mounted at DX cameras (crop factor 1.5x body, series other than D700, D800, D3, D3x, D3s, D4) then it becomes 1.5 x 800mm = 1200mm lens.


      • Christine

        Thanks Raymond. I understand the teleconverter, Nasim was saying 400 mm is 800 mm effective. What I don’t understand is why this is 1200 mm equivalent… What is the mechanism? Is it that those cameras are at normal lens at 50mm rather than 35 mm?