# How do I calculate the field of view of a 50mm focal length biconvex lens with the retina as sensor?

Hi I need to know the field of view of a 50mm focal length lens.

I know the field of view is dependent on focal length of the lens and the image format dimension (i.e., dimensions of the sensor).

If the sensor is our eye (retina) how do I calculate the field of view?

• you mean extracting the retina and making a photo camera of it or replacing our eye lens and cornea with 50mm lens? the effect will be different because of the vitreous body inside our eyes. Jan 26, 2016 at 9:26
• Ok what would be the Field of View angle of there is no vitreous body? @szulat Jan 26, 2016 at 9:34
• taking the eyeball diameter of ~22mm it would be 25° FOV - the formula is 2*arctan(dimension/(2*focal)) - with most of the field being out of focus because of the curved retina surface Jan 26, 2016 at 9:59
• What are you trying to figure out by asking this question? How big the retina is? What the actual focal length or field of view of the eye is? Or, something about the 50mm lens? Jan 26, 2016 at 12:00
• Possible duplicate of What is "angle of view" in photography? Jan 26, 2016 at 12:00

## 2 Answers

There's a quite good article here about the human vision system in comparison with photographic ones.

The human vision system is not complete considering only a lens and a retina. Your vision is highly interpreted by your brain, and for this reason you can't make direct comparisons.

From long experience the focal length generally used to produce a field of view and perspective that is "comfortable" for humans is the 50mm focal length combined with a "full frame" sensor. Some people prefer the 43mm focal length as it is a perfect normal for the full frame sensor. On crop frame 28mm is roughly equivalent to 43mm, and 35m is generally considered a reasonable choice for a this purpose. But human vision has quite different properties for a 2D image and this does not work perfectly.

This question deals with the same problem and you'll see how contentious this all is from the answers and comments.

• and since the question was about applying 50mm lens to a human retina, note that the effect would be very different from using 50mm lens on a full frame camera, even though 50mm is considered "normal" or "human equivalent" focal length Jan 26, 2016 at 11:32

A picture paints a thousand words

• While a picture might paint a thousand words, the picture assumes the sensor and lens are separated by air. But the OP's question was about the human retina, which is normally separated from the lens by vitreous humor, not air.
– scottbb
Nov 30, 2018 at 20:24
• A frame of 35mm film is actually 36mm wide, so the angle of view would be 40°, not 39. The vertical angle I've the 24mm height of the frame would be 27°
– scottbb
Dec 1, 2018 at 1:03