What's more important; wide angle lenses or telephoto lenses?

Started Jan 25, 2013 | Questions thread
Gerry Winterbourne Forum Pro • Posts: 13,189
Re: What's more important; wide angle lenses or telephoto lenses?

hikenhi wrote:

Gerry Winterbourne wrote:

hikenhi wrote:

I'm not sure if you know this but each of our eyes have about a 50mm view in FF or 35 mm in APS-C.

He can't know it because it's not true. Those lenses have a diagonal AOV of about 45 degrees. Our eyes each have an AOV of over 120 degrees horizontally, a bit less vertically. Both eyes together cover a horizontal AOV of about 220 degrees.

But this is what I actually saw crisply - at 70mm



Peripheral vision doesn't count.

Ah - a new rule ... If you meant "our visual acuity is strongest over a relatively narrow angle" why didn't you say so?

Rods & Cones man, anatomy 101

There isn't a crisp cut off between acuity across one's FOV. Rods are relatively sparse in the central area of vision, cones are concentrated there: but their concentrations taper in opposite directions so there's no point you can define an actual "angle of view" for an eye.

Two things make what you say effectively irrelevant anyway. First, we very rarely look with just one eye: what matters is the combined vision of both eyes working together. Where the two AOVs overlap is roughly an ellipse that's longer vertically. As my final illustration (which I've left here) shows, the area we really see is narrower than you say.

Second, we never actually keep our eyes and heads still so the area we "see" depends on what we move our heads-eyes to look at. Indeed, if we keep them perfectly still - and it has been done in laboratory conditions - we lose all vision after about 1/2 minute: fortunately it returns on release. Take a middle course and keep the head still but move the eyes and we can actually cover most of the wider area I described.

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Gerry
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First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne

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