How far can we see with our eyes? How far can 300mm lens 'see'?

[Pikme]

Sometimes I am just amazed at how far away the 300mm end of the 75-300mm lens can photograph objects in the landscape. On a clear day, I can easily photograph the San Francisco skyline from Mt. Diablo, a distance of more than 30 miles, or cars on the highway, boats in the bay, trees and shrubs from more than 15 miles away, etc. I can spot (visually and with lenses) coyotes, deer and even birds from many miles away in the hills.

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

 

[Trafford]

Sometimes I am just amazed at how far away the 300mm end of the 75-300mm lens can photograph objects in the landscape. On a clear day, I can easily photograph the San Francisco skyline from Mt. Diablo, a distance of more than 30 miles, or cars on the highway, boats in the bay, trees and shrubs from more than 15 miles away, etc. I can spot (visually and with lenses) coyotes, deer and even birds from many miles away in the hills.

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

 

[Pikme]

Well the Sun is a few million miles away, the galaxies in the Milky Way farther still.

thanks!

 

[Paul Auclair]

Sometimes I am just amazed at how far away the 300mm end of the 75-300mm lens can photograph objects in the landscape. On a clear day, I can easily photograph the San Francisco skyline from Mt. Diablo, a distance of more than 30 miles, or cars on the highway, boats in the bay, trees and shrubs from more than 15 miles away, etc. I can spot (visually and with lenses) coyotes, deer and even birds from many miles away in the hills.

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

 

[Iskender]

The implication being, that only dimness and angular size are the only limits - we can't see things below a certain width, and we can't see things that are too dim. Point sources (stars) muddle things a bit, but they aren't the farthest objects we can see in any case.

The best guess is probably Messier galaxy 81:

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messier.seds.org

Several people claim it to be naked-eye visible. Estimated distance is 12 million light years, or about 1000000000000000000000000 metres from here. Hobbyist astronomers often consider this the farthest object anyone can see with the naked eye.

A more conventional candidate, which is readily visible to most people under dark skies, is Messier object 31, better known as the Andromeda Galaxy:

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en.wikipedia.org

This one's more than two million light years from here.

 

[Pikme]

a 300mm focal length will simply enlarge an object 6X...6X50=300.

Thanks, that is helpful.

I'm not a scientist, so maybe I am just being like a child, amazed that we can actually see so far away when the air is clean.

 

[Iskender]

...to my understanding....a (35mm film equivalent) 50mm focal length lens is standard. the term standard means the 50mm focal length captures an image which appears to us the same as we see it (how our human eyes see the world).

Which is, of course, a very nebulous concept. The human eye is a single-lens fisheye optic, which one source described as suffering from "all possible optical aberrations". Our brain takes that input, and rams it until we get excellent optical output. There are black holes right in the original signal!

And while we have a fisheye angle of view, the direct vision angle of view is very small, and may feel smaller still if we concentrate. So, depending on perception, out vision goes between fisheye/ultra wide angle view, and probably something like 1000 mm equivalent.

And then there's the silly dynamic range which allows us to see stars and craters on the moon within a few degrees of each other.

Closer to everyday photography, I've heard some photographer say that 35mm was more like the way he sees the world. But for some, 50mm no doubt feels the most natural, even if "natural" is a really strange thing in this case!

 

[Klarno]

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

The most distant object visible to the naked eye is the M81 galaxy. So we can see up to...70 quintillion miles away.

--

http://www.photoklarno.com

 

[Michael M Fliegel]

Good answer! :-D

 

[Colin K. Work]

...to my understanding....a (35mm film equivalent) 50mm focal length lens is standard. the term standard means the 50mm focal length captures an image which appears to us the same as we see it (how our human eyes see the world).

Which is, of course, a very nebulous concept. The human eye is a single-lens fisheye optic, which one source described as suffering from "all possible optical aberrations". Our brain takes that input, and rams it until we get excellent optical output. There are black holes right in the original signal!

And while we have a fisheye angle of view, the direct vision angle of view is very small, and may feel smaller still if we concentrate. So, depending on perception, out vision goes between fisheye/ultra wide angle view, and probably something like 1000 mm equivalent.

And then there's the silly dynamic range which allows us to see stars and craters on the moon within a few degrees of each other.

Closer to everyday photography, I've heard some photographer say that 35mm was more like the way he sees the world. But for some, 50mm no doubt feels the most natural, even if "natural" is a really strange thing in this case!

 

[Anders W]

Sometimes I am just amazed at how far away the 300mm end of the 75-300mm lens can photograph objects in the landscape. On a clear day, I can easily photograph the San Francisco skyline from Mt. Diablo, a distance of more than 30 miles, or cars on the highway, boats in the bay, trees and shrubs from more than 15 miles away, etc. I can spot (visually and with lenses) coyotes, deer and even birds from many miles away in the hills.

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

 

[Michael M Fliegel]

I also find 35mm more natural than 50mm, but for wide angle, the wider the better. I prefer 22 and 24 to 28mm any day.

 

[bidule5]

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

The most distant object visible to the naked eye is the M81 galaxy. So we can see up to...70 quintillion miles away.

--

http://www.photoklarno.com

Not sure that M81 is visible with naked eyes, but M31 (Andromeda), 2.5 million light-years away, clearly is.

 

[edwin willis]

The eye has no control of where the photons come from If enough photons reach your eye the eye will register them with no distance being measured

 

[Klarno]

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

The most distant object visible to the naked eye is the M81 galaxy. So we can see up to...70 quintillion miles away.

--

http://www.photoklarno.com

Not sure that M81 is visible with naked eyes, but M31 (Andromeda), 2.5 million light-years away, clearly is.

M81 is just under the magnitude threshold for what is considered visible to the naked eye, but supposedly it's visible to experienced astronomers under "exceptional conditions".

 

[bidule5]

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

The most distant object visible to the naked eye is the M81 galaxy. So we can see up to...70 quintillion miles away.

--

http://www.photoklarno.com

Not sure that M81 is visible with naked eyes, but M31 (Andromeda), 2.5 million light-years away, clearly is.

M81 is just under the magnitude threshold for what is considered visible to the naked eye, but supposedly it's visible to experienced astronomers under "exceptional conditions".

 

[Paul Auclair]

a 300mm focal length will simply enlarge an object 6X...6X50=300.

Thanks, that is helpful.

another point about these super teles not meant for shooting 'only' far away stuff is their minimum focus distance.

the 40-150Pro is less than 3 feet.

the 50-200 is less than 4 feet.

shooting a hummingbird or a flower or a caterpillar or a bumble bee or a butterfly at these close distances makes for some pretty nicely detailed and 'uncropped' images.

I'm not a scientist, so maybe I am just being like a child, amazed that we can actually see so far away when the air is clean.

 

[boxerman]

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

Bottom line first: If you mean "how much bigger are objects in the viewfinder with a 300 mm lens compared to with the naked eye?" then, sadly, the answer is only about 7.5X. So, objects at 7.5x the distance will appear as they do with our naked eye. If you mean "how much farther away can objects be to resolve small detail (e.g., how much farther away can you be and still determine the digits on a watch or clock), then the answer is less, depending on the resolution of the digital display (VF or LCD). With current technology, this ranges from about 4x to a sad 2.5x. With an optical viewfinder, you aren't limited by pixel size so you get the full 7.5x advantage.

Here are three different reasoning paths that lead to some surprising results, including what I'll call for dramatic effect "the myth of the normal (35-50) lens."

FIRST: It's true that if you are interested only in registering the existence of a point source of light, then all you need is to find the existing thing in the universe that is farthest away yet emits a sufficient amount of light to be detected. Hence, we just ask the astronomers. And I think we got some pretty good input on that.

However, if you ask "what impressions was the OP registering that he wanted to have a better take on," the point source answer is not very responsive. A better technical question in the vicinity of what the OP was reacting to would be "what's the farthest thing on earth that one can see?" Taking a cue from the astronomical version of the question, one might ask "what's the farthest city (i.e., the city for which register that there is some light there) that one can see at night? This gets mucky since it obviously depends on where you are, but also on horizons, etc. Since it's already not a very good rendering of the OPs experiential question (in my opinion), I'll drop it.

SECOND: Here's what I think is a pretty good rendering of the OPs question in technical terms. "If I put the eyepiece of my camera to my eye, what's the magnification of a 300mm lens, compared to using my unaided eye?" Having an experimental nature, I just pulled out my E-M5 and looked through the viewfinder to see at what FL the image appeared the same size as with my unaided eye. This is pretty easy to tell by picking a goodly-sized reference object, and systematically looking through the viewfinder and then pulling the camera away to judge whether the object appeared bigger or smaller. It turns out, surprisingly, that 40mm (plus or minus 10 percent) does it! So, 80mm is "normal" as determined with this method! Sadly, this means that the 300 mm. lens is only 7.5x. So, using a 300 mm lens, objects appear only 7.5x closer.

I think this probably answers the OPs question pretty well, corresponding to the impression he has that things get bigger, so you can see farther. It probably answers the question "if I can see (so as to recognize) X at a certain distance, then how much farther away can I see (recognize) X with a 300mm lens?"

The myth of the normal lens, of course, is just mixing apples and oranges. As a few others have noted, the "normal lens" is derived (I'm pretty sure) from what a "normal" print looks like from a "normal" distance, an obviously fuzzy concept. What's the new normal in print sizes and distances of view? It is NOT "what is my impression of size, looking through the viewfinder?" which leads to different results (and depends on the camera's viewfinder's optical specs, of course). This "normal" probably also has nothing much to do with the experience that the OP is reacting to.

THIRD: One could ask a yet different, and equally sensible question. If I can just resolve features at distance D when looking with the naked eye, what's the distance I can resolve them with a 300 mm lens?" It's more like "if I can read the numerals on a clock as far as D away, how far away can I see them with a 300mm lens?" Here, visual acuity is in play.

According to Wikipedia (donate today!), 20/20 vision corresponds, roughly, to being able to resolve objects that subtend an arc second. You'd know what this means if you have paid attention to Apple advertising. A "retina" display has a resolution better than the human eyes, which happens to be about 600 pixels per inch when viewed at about one foot distance. If the viewfinder is optical, we've already answered the "how much farther" question: 7.5x the distance. Sadly, viewfinder are still limited by pixels; current camera pixels are generally NOT "retina" quality.

Looking into my E-M5 viewfinder, I see that the vertical size of the viewfinder covers about three inches of real image at one foot (using a 40 mm focal length). So, that should require about 1800 pixels. The vertical dimension of the E-M5 viewfinder is about 600+ pixels, so we're short by about a factor of three. Instead of 7.5x, the limits of viewfinder pixels brings us down to only 2.5X the distance. Oof. If you're looking to see as much detail as possible, then the 300mm does not really do all that well. It DOES give you the impression (in terms of size of moderately large objects) of giving you 7.5x, though. (Sensor resolution is plenty, here. It's like 6x that of the viewfinder, so it is not a limiting factor.)

As Anders points out, you can crank up the magnification of the viewfinder, and you'll then get effect of the full 7.5x optical equivalence as far as resolving detail goes.

Using the LCD is better. It lays out about 650 pixels over the roughly 2 vertical inches of the display, so is just a factor of 2 short of retina resolution. Still, you don't get the full optical advantage in seeing small features, but only about half of it (unless you use the "magnify" feature of he camera). As soon as displays offer truly retina resolution, then the optical computation is all we'll need to do.

By the way, as Anders pointed out Paul did the optical calculation incorrectly, coming up with 6x. Anders did it correctly, coming up with 12x, although the main point here is that the usual "normal" does not relate, I don't think, to the OPs experiential basis for asking.

--
The BoxerMan

 

[honeyiscool]

...to my understanding....a (35mm film equivalent) 50mm focal length lens is standard. the term standard means the 50mm focal length captures an image which appears to us the same as we see it (how our human eyes see the world).

Which is, of course, a very nebulous concept. The human eye is a single-lens fisheye optic, which one source described as suffering from "all possible optical aberrations". Our brain takes that input, and rams it until we get excellent optical output. There are black holes right in the original signal!

Not only that, we have awful resolution in any one image, but our eyes are in constant motion, and that helps us achieve much greater resolution.

So, basically we're an E-M5 II. We use sensor shift to increase maximum resolution, and software correction to make up for flaws in our lenses.

 

[Anders W]

So I am curious - does anyone know how far we can actually see with our eyes? Or how far these telephoto lenses can 'see'?

Bottom line first: If you mean "how much bigger are objects in the viewfinder with a 300 mm lens compared to with the naked eye?" then, sadly, the answer is only about 7.5X. So, objects at 7.5x the distance will appear as they do with our naked eye. If you mean "how much farther away can objects be to resolve small detail (e.g., how much farther away can you be and still determine the digits on a watch or clock), then the answer is less, depending on the resolution of the digital display (VF or LCD). With current technology, this ranges from about 4x to a sad 2.5x. With an optical viewfinder, you aren't limited by pixel size so you get the full 7.5x advantage.

Here are three different reasoning paths that lead to some surprising results, including what I'll call for dramatic effect "the myth of the normal (35-50) lens."

FIRST: It's true that if you are interested only in registering the existence of a point source of light, then all you need is to find the existing thing in the universe that is farthest away yet emits a sufficient amount of light to be detected. Hence, we just ask the astronomers. And I think we got some pretty good input on that.

However, if you ask "what impressions was the OP registering that he wanted to have a better take on," the point source answer is not very responsive. A better technical question in the vicinity of what the OP was reacting to would be "what's the farthest thing on earth that one can see?" Taking a cue from the astronomical version of the question, one might ask "what's the farthest city (i.e., the city for which register that there is some light there) that one can see at night? This gets mucky since it obviously depends on where you are, but also on horizons, etc. Since it's already not a very good rendering of the OPs experiential question (in my opinion), I'll drop it.

SECOND: Here's what I think is a pretty good rendering of the OPs question in technical terms. "If I put the eyepiece of my camera to my eye, what's the magnification of a 300mm lens, compared to using my unaided eye?" Having an experimental nature, I just pulled out my E-M5 and looked through the viewfinder to see at what FL the image appeared the same size as with my unaided eye. This is pretty easy to tell by picking a goodly-sized reference object, and systematically looking through the viewfinder and then pulling the camera away to judge whether the object appeared bigger or smaller. It turns out, surprisingly, that 40mm (plus or minus 10 percent) does it! So, 80mm is "normal" as determined with this method! Sadly, this means that the 300 mm. lens is only 7.5x. So, using a 300 mm lens, objects appear only 7.5x closer.

When looking through the EVF, you need to take the magnification of the viewfinder into account. On the E-M5, it is 0.575 for a 25 mm "normal" lens. Hence there is nothing surprising about the fact that you need to get to 40 mm (43.48 to be more exact) before things look the same size when seen through the EVF as with your naked eyes.

I think this probably answers the OPs question pretty well, corresponding to the impression he has that things get bigger, so you can see farther. It probably answers the question "if I can see (so as to recognize) X at a certain distance, then how much farther away can I see (recognize) X with a 300mm lens?"

The myth of the normal lens, of course, is just mixing apples and oranges. As a few others have noted, the "normal lens" is derived (I'm pretty sure) from what a "normal" print looks like from a "normal" distance, an obviously fuzzy concept. What's the new normal in print sizes and distances of view? It is NOT "what is my impression of size, looking through the viewfinder?" which leads to different results (and depends on the camera's viewfinder's optical specs, of course). This "normal" probably also has nothing much to do with the experience that the OP is reacting to.

THIRD: One could ask a yet different, and equally sensible question. If I can just resolve features at distance D when looking with the naked eye, what's the distance I can resolve them with a 300 mm lens?" It's more like "if I can read the numerals on a clock as far as D away, how far away can I see them with a 300mm lens?" Here, visual acuity is in play.

According to Wikipedia (donate today!), 20/20 vision corresponds, roughly, to being able to resolve objects that subtend an arc second. You'd know what this means if you have paid attention to Apple advertising. A "retina" display has a resolution better than the human eyes, which happens to be about 600 pixels per inch when viewed at about one foot distance. If the viewfinder is optical, we've already answered the "how much farther" question: 7.5x the distance. Sadly, viewfinder are still limited by pixels; current camera pixels are generally NOT "retina" quality.

Looking into my E-M5 viewfinder, I see that the vertical size of the viewfinder covers about three inches of real image at one foot (using a 40 mm focal length). So, that should require about 1800 pixels. The vertical dimension of the E-M5 viewfinder is about 600+ pixels, so we're short by about a factor of three. Instead of 7.5x, the limits of viewfinder pixels brings us down to only 2.5X the distance. Oof. If you're looking to see as much detail as possible, then the 300mm does not really do all that well. It DOES give you the impression (in terms of size of moderately large objects) of giving you 7.5x, though. (Sensor resolution is plenty, here. It's like 6x that of the viewfinder, so it is not a limiting factor.)

As Anders points out, you can crank up the magnification of the viewfinder, and you'll then get effect of the full 7.5x optical equivalence as far as resolving detail goes.

Using the LCD is better. It lays out about 650 pixels over the roughly 2 vertical inches of the display, so is just a factor of 2 short of retina resolution.

The EVF pixel count of the E-M5 is actually a bit higher than that of the rear display (800x600 for the EVF versus 640x480 for the display). I guess you ended up with about 650 pixels vertically for the rear display based on its total dot count of 610,000. But those dots are not to be confused with pixels. On a normal LCD screen, you have to divide the dot count by three to get the pixel count. But due to the special display technology used in the E-M5 OLED, you should instead divide by two, for a pixel count of 305,000, corresponding to the VGA resolution of 640x480.

Still, you don't get the full optical advantage in seeing small features, but only about half of it (unless you use the "magnify" feature of he camera). As soon as displays offer truly retina resolution, then the optical computation is all we'll need to do.

--
The BoxerMan