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My main go-to equipment:

  1. Sony A7s II,
  2. Sony FE 55mm f1.8 and
  3. Sony FE 16mm-35mm f4.

Within this range of focal length I have quite a good feel for what picture is at what focal length.

I recently added a Sony FE 70mm-200mm F4 to my arsenal and must say, that my intuition regarding focal length abandons me whilst using this lens.

What I try to do is: before I look through the viewfinder, I try to draw the frame in my mind, as to what is in the shot, and how much of the total picture it is going to cover. I quite fail with the 70mm-200mm.

Now there are 2 things I thought of;

  1. The range from 16mm-55mm is more narrow than 70mm-200mm.
  2. The ultra-wide angles are more recognizable I think due to the strong surrealistic look, so that covers a few focal lengths.

My question is; how do you regard your intuition on focal lengths? What would your experience dictate on whether this can be learned/trained?

Sidenote: The idea that one could determine the focal lengths of single shots in a movie intrigues me.

Michael C
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onimoni
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2 Answers2

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Regularly using a particular focal length with a particular format size (ie. APS-C, 35mm/FF, µ4/3) will allow you to learn how to visualize the framing a little more accurately. But most of us will probably always be a little better at visualizing the difference between 16mm and 24mm than we are at measuring the difference between 200mm and 300mm with our unaided eyes, even though the ratio is the same between the two focal lengths in both cases. This is because what we are really learning and looking at isn't the focal length, per se, it is the angle of view that focal length gives with a camera having a particular frame size.

Assuming a full frame camera, a 16mm lens gives about a 100° horizontal angle of view when the camera is held in landscape orientation. A 24mm lens gives about a 74° horizontal angle of view. On the other hand, 200mm and 300mm lenses give 10° and 6.8° horizontal angles of view respectively. It's a lot easier for me to visualize the difference between 100° and 74° than it is to visualize the difference between 6.8° and 10°.

Michael C
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  • Assume a plain (no depth) background, and a 2D object (e.g. paper) facing towards the camera. Now, here we could only guess a focal length based on the distortion, given that we know how a sheet of paper should look like.

    Do you have an idea, as to how much depth an object should need, to be able to make an educated guess about the focal length?

    I'm guessing that evident distortion will take place in the lower end of the focal lengths. So, whe you're, say, above 135mm, you would need a certain depth of the object, and also knowledge of the object, to make an educated guess. Thoughts?

     – onimoni Mar 24 '17 at 14:38
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    That's really a different question and should be asked as a separate question. But realize that perspective has nothing to do with focal length, it's determined by camera position. What is the difference between perspective distortion and barrel or pincushion distortion? – Michael C Mar 24 '17 at 16:21
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You can definitely learn to visualize the framing or field of view you get from a certain focal length simply by using it a lot.
This will likely go faster if you use fixed focal lengths and preferably only one for a longer duration (a month or a couple of sessions). You could also tape your zoom at a given focal length during such a period. After you did this with a couple of focal length, you will probably have a rough feeling for the focal lengths in betweenn. This can also improve your overall photography skills, as it will force you to make do with a given focal length.

If you need some motivation to try this, maybe look for a photo challenge like this "Single in month x", where the aim is to use only one lens for a month.

Grebu
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