Landmannalaugar Sheep and Cotton Grass

What Focal Length is Closest to Human Eyesight? (Podcast 591)

Following a recent question, today we're going to explore how we see and how we perceive a scene, in relation to the focal length numbers we are familiar with from our camera lenses. Before we start, I'd like to apologize for skipping last week's episode. I'm still working heavily on...

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Martin Bailey
Martin Bailey is a nature and wildlife photographer and educator based in Tokyo. He's a pioneering Podcaster and blogger, and an X-Rite Coloratti member.
  • Steve Jarrell
    Posted at 21:37h, 02 October Reply

    Very nicely done and thought provoking.



    • Martin Bailey
      Posted at 22:45h, 02 October Reply

      Thanks, Steve! I’m pleased you enjoyed it.

  • Joshua Kuhn
    Posted at 04:01h, 05 October Reply

    Thank you for this write up. Next time I see a silly argument about what length focal represents our eye, I can just link this blog.
    I completely agree with you. The first time I heard the idea about 35mm or wider representing the natural view from our eyes I thought about it the next time I was out with my camera. What??? They must have very different eyes from me. To me it actually feels more like 80-90mm is that natural view.

    You hit the nail on the head talking about perspective. I think this is where others get confused. The photo is all about perspective, but they want to compare field of view which doesn’t mean much when comparing our vision to a photo. We have a huge field of view of about 210 degrees, A 10mm lens gives a fov of 121 degrees on a full frame camera.

    Of course human vision is much more complicated. We can really only look at one point at a time, and our eyes are constantly moving and focusing on whatever point we are looking at. It it pretty hard to compare a photo to human vision at all really, but you did a great of thinking it through and trying to explain it.


    • Martin Bailey
      Posted at 09:49h, 08 October Reply

      THanks for the comment Josh! I’m pleased this rang a bell with you.

      One comment I had on Twitter was interesting too. When viewing very large prints from wide angle lenses, we tend to walk right up to them and explore the details. Because you can actually crop areas out of wide-angle photographs and they look the same as images shot with long lenses if you shoot from the same distance, you can enjoy both aspects from a wide shot if printed very large. But if you step back, and look at the entire print, you are back to having too much for it to feel totally natural. Although, as I mentioned above, I do still like the wide angle shot and feel they are important as part of the storytelling experience too.

      It’s all fun to think about! 🙂


  • Stefan
    Posted at 21:50h, 13 October Reply

    Hey your 5dsr has a viewfinder magnification of 0.71x that would be why you get a result of ~70mm instead of 50 right?

    • Martin Bailey
      Posted at 16:53h, 14 October Reply

      Hi Stefan,

      No, I don’t believe that’s the case. Although the 5Ds R has a 0.71x magnification, it still only has a 100% field of view. My photos are not 0.71% of what I see through the viewfinder, they are 100%, so if I align the edges of the frame with what I see in real life, I am seeing 100% of what the photograph will include, which in this case, gives me approximately 68mm. I’ll do some more tests when I have time, but I’m pretty sure the magnification doesn’t affect the test that I did.


  • Chas
    Posted at 05:02h, 23 May Reply

    Your final advice to put the camera up to the eye and zoom until the viewfinder image is the same size that you see with the unaided eye ignores the fact that virtually all modern cameras have some magnification factor in the viewfinder. those I currently have access seem to be somewhere between 0.8 and 0.7. There are optical devices that attach to the back of the lens that project the image onto a ground glass and have a magnification of 1.0, sadly I don’t have one to try.

    • Martin Bailey
      Posted at 08:59h, 26 May Reply

      Hi Chas,

      It’s more about the field of view of the viewfinder than the magnification. If you have a field of view 100% viewfinder, then regardless of what you see, you will get everything in the frame in your final image, so using those image boundaries is completely valid. Granted, if you have a camera that does not have 100% field of view in the viewfinder, that advice is not going to help, but only in that case.

      Also, regarding adding a physical diopter to adjust the viewfinder, that is for eyesight correction. It won’t make the field of view of a sub-100% finder wider, as far as I’m aware.


  • Paul Mundell
    Posted at 17:07h, 07 April Reply

    Just read this post and thoroughly agree. I’ve done this in the past for landscapes. Look through the view finder with one eye while observing with the other. Adjust the zoom until both images superimpose. For me it’s around 55mm. I’ve never thought of trying for near distance to see if it’s different.

    • Martin Bailey
      Posted at 20:09h, 07 April Reply

      Good to hear Paul.

      Thanks for taking the time to comment.

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