How To Calculate Camera Field Of View
Many things in this world go hand-in hand: cookies and cream, peanut butter and jelly, bagels and salmon… In the photography world, nosotros've got field of view and lens focal length.
Ok, these two aren't quite as tasty and the food combos, but they're notwithstanding pretty important!
You meet, humans and cameras see quite differently.
Humans accept binocular vision, meaning that nosotros run across with two eyes, not merely one. This allows us to accept a fairly wide field of view: 180 degrees, requite or take a few degrees of peripheral vision.
Camera lenses, with the exception of some fisheye lenses, see much less than that. Knowing buthow much of the world your camera will meet is a cardinal factor in choosing which lens to utilise.
Unsurprisingly, many beginner photographers merely remember nearly focal length when they go to purchase a new camera lens. In reality, field of view is really what's guiding their decision.
Simply defined, field of view (FOV) in photography is the observable earth y'all tin run across through your camera at any given moment. It'south usually expressed in terms of degrees, referring to the literal angle of view your lens allows your sensor to come across.
Why does field of view matter?
Well, what most of us are doing when buying a lens according to focal length is imagining what field of view it will create. Information technology's ultimately what determines what kind of lens you lot're going to purchase.
It'due south likewise useful to know the what field of view if you lot have a express space to work in and you need to determine which lens to employ. Say, for case, yous're shooting portraits in a minor garage and want to use a prime lens. Knowing the FOV will help you know exactly what focal length volition piece of work for y'all.
Let's have a look at just what field of view is, how it relates to lens focal length, and how it ultimately tin guide you in knowing which lenses are best for which situations.
What is Focal Length and Field of View?
Reverse to how it might seem, the lens focal length doesn't refer to how long the lens is.
Rather, it'southward the distance from the image airplane to the optical eye of the lens when the lens is focused at infinity.
(The optical center is where all the low-cal rays converge subsequently passing through the lens elements.)
Put another mode, the focal length is simply the altitude from the camera sensor to the place where the light rays converge after going through the lens elements.
One thing to keep in heed is that inside your camera nosotros're actually working with round images. Considering your sensor is a rectangle, information technology captures the rectilinear portion of this cone. That rectangle comprises your field of view.
At present the confusing thing is thatangleof view andfield of vieware often used interchangeably, and it's how well-nigh manufacturers refer to field of view, merely they're not quite the same thing.
The bending of view is the athwart size of the view cone. (See diagram above.) You might too run across information technology referred to every bit the angular field of view.
The overall field of view is the maximum area your sensor can capture at a given lens focal length of lens. It's the lens focal length combined with the size of your camera's sensor that determines this field of view.
So why do manufacturers focus more on lens focal length than field of view?
Well, sensor size isn't standardized. Non just is a full-frame sensor on a Catechism photographic camera likely to be a slightly unlike size than a sensor on a Nikon FX camera, simply fifty-fifty next-generation cameras of the aforementioned line can utilise different sensor sizes.
That means the field of view will be different in each case.
Focal length, on the other hand, is the same regardless of sensor size – it volition e'er exist the altitude from the sensor to the optical sensor. That means a 35mm lens is a 35mm lens no matter who makes it or what camera it's paired with.
As a result, information technology's much easier for camera manufacturers to reference.
What affects field of view?
The reply is unproblematic: sensor size and lens focal length. Distance from your discipline (i.e. "zooming with your anxiety") may look similar it'southward affecting your field of view, but it's not actually changing the angle of view inside your lens.
- Sensor Size
Different camera sensor sizes have innately dissimilar fields of view. Smaller sensors volition have a narrower FOV. Larger sensors volition innately have a wider FOV.
Since 35mm film cameras were the norm back in the solar day, that's the visual field all digital cameras are compared to. Full-frame sensors are more-or-less the same size as what was 35mm film.
Smaller sensors capture a smaller portion of the image cone and therefore have a smaller FOV than a total-frame sensor photographic camera. A medium format camera, having a larger sensor, will have a larger FOV than a total-frame.
- Lens Focal Length
If you're always shooting with the same sensor (i.e. the aforementioned camera), then the primary thing that will change your field of view is the lens what lens focal length you cull to utilise.
The near important matter to remember is that shorter focal lengths accept a larger angle of view. Conversely, longer focal lengths volition have a narrower angle of view. This holds true for both prime lenses and zoom lenses.
For example, shorter lens focal lengths (i.e. 16mm, 24mm, and 35mm) take a larger angular field of view, hence the term "wide-bending" lens.
These lenses as well tend to have a level of distortion that needs to be addressed in postal service-processing, but they capture a large amount of the scene in forepart of them.
A "normal" lens is one where the FOV looks natural and is more than or less what the human being centre would expect from an image – in that location's no noticeable expansion or pinch. The swell-fifty (50mm) is considered normal in 35mm (full-frame) photography and an 80mm lens hits the mark for those shooting medium format.
"Long lenses" (including telephotos) have longer focal lengths than either a normal or wide-bending lens, and therefore a narrower angle of view. Telephotos, in particular, accept a degree of magnification that makes it easier for a subject to upfill more than of the frame.
How is Field of View (FOV) Calculated in Photography?
Field of view is calculated through a fleck of simple trigonometry.
Don't worry if math isn't your matter. We're including a field of view chart downward below. This section is really more for those who love to geek out on how things work.
Permit's have some other look at the lens diagram again:
A closer await shows us that the angle of view is actually the angle between whatever low-cal captured on the horizontal dimension, and any lite captured at the edge. (The reddish lines mark the edge.)
When the FOV is measured in degrees, like on manufacturer's lens specs, they're referring to the angular field of view in the horizontal dimension – from the correct to the left edge of the frame. Vertical FOV is measured from the elevation to bottom. Diagonal FOV is measured from corner to opposite corner.
(Most of the time horizontal FOV is all nosotros need to know. The exception is the example given to a higher place where you demand to shoot in a very confined expanse. In that instance, you lot may demand to know your field of view exactly.)
Using the image above and the magic of trigonometry, we can calculate the overall field of view with the equation beneath:
Angle of view (in degrees) = two ArcTan (sensor width / ( 2 x focal length))) * (180/π)
Annotation: Y'all only need the (180/π) office if your calculator is working in radians. If yours is working in degrees, get out that function out!
Since this equation has the sensor size as 1 of the factors, it too covers ingather gene. (Think, the smaller the sensor size, the smaller the FOV.)
We tin can also go backwards: if yous know your field of view and your sensor size, you can figure out what focal length of lens to use. Pretty nifty, no?
This is pretty much all there is to it…with the exception of a few adjustments to be made for the baloney of super wide-bending lenses (fish-eyes) and the magnification gene of macro lenses.
Of course, yous won't ever have to practice the math yourself (unless yous want to). There are plenty of field of view charts (like the ones below) and online field of view calculators available.
Some of the calculators even let you lot to enter in other variables, besides, like the photographic camera altitude from the subject, the distance from the bailiwick from the background, etc.
So what does all this hateful in practical terms? Let'southward take a await.
Lens Field of View Comparing
Here'southward a field of view sampling of some of the more than mutual focal length lenses we're likely to be shooting with.
Please note that all of these images were taken on a full-frame photographic camera. Crop-sensor cameras will have a smaller angular field of view using the same focal length.
All of the images in a higher place were taken from the same location on a full-frame Sony A7 III. The only matter that changed was the focal length of the lens.
What lens you'll demand for a given state of affairs really depends on the nature of the prototype you're looking to capture.
For example, if you want a lot of the background included in an image, yous'll want to choose a lens with a larger field of view (and a shorter focal length).
The wider lenses like the 16mm or 24mm are used for landscapes, cityscapes, and astrophotography. Photojournalists often favor a 35mm lens – it's wide enough to capture a fair amount of background yet has less baloney than its wider cousins.
For an image with a "natural" wait – one without a lot of baloney or magnification – the FOV offered by a 50mm or even an 85mm lens volition do the trick. In fact, 85mm prime lenses are favorites of many portrait photographers.
Equally we become into the longer lenses the level of compression and magnification goes upward as well. A fiddling bit can actually be quite flattering in portraits, which is why 100mm, 105mm, and even upwards to 135mm can exist found in a portrait photographer's lens collection.
(Many portrait photographers favor prime number lenses over zoom lenses, equally prime lenses create sharper images.)
To make things that are far away fill your camera'due south visual field, choose something with a very narrow field of view. A telephoto lens that hits somewhere in the 200mm or 300mm range will have a overnice level of magnification. These are the lenses that wildlife and sports photographers favor.
Field Size
Speaking of magnification, some other important concept to understand when looking at field of view is field size or how much of the subject field and background are visible in your photographic camera's field of view.
This is determined by the altitude betwixt the camera and the subject and the focal length of the lens. A wider field of view volition have a larger field size; a narrower field of view will have a smaller field size.
Broad-angle lenses will aggrandize a perspective, providing a larger field size. Telephoto lenses volition compress a perspective, thereby magnifying the field of study.
For example, a 200mm lens will overstate objects 2x more than than a 100mm lens does and 4x more than a 50 mm lens does. The field size is the reciprocal, in this case, either one/2 or 1/4 of the dimension.
If you're using a 50mm lens and want an object to be 3x larger in the frame, switch to a 150mm lens. Etc.
Lens Angle of View Nautical chart Examples
Here's a different style of looking at it, this time from the perspective of a crop-sensor camera.
Here y'all can see how the 135mm telephoto lens has the narrowest athwart field of view at 12 degrees. A 35mm lens has a considerably larger conical visual field with a 46-caste FOV. A focal length of 16mm in with a FOV of 84 degrees.
If you want to go the whole grunter and capture a 180-degree view, you'd demand a 10.5mm total-frame fisheye lens. That volition, of course, give yous plenty of baloney, but some actually like the effect.
Bumping up to a total-frame sensor, you tin meet that it takes a longer focal length to become the same angular field of view:
Credit: Nikon U.s.
On a total-frame photographic camera, a 200mm lens would get a 12-caste FOV, a 50mm lens would come in at 46 degrees, and a 24mm lens would come up in at 84 degrees. It would accept a 16mm fish-eye to get the full 180-degree horizontal FOV.
For a more definitive quick reference chart, take a look at this one from Nikon, roofing FX, DX, and even CX formats:
This chart covers the focal lengths of normal, rectilinear photographic camera lenses. Fisheye FOV is a bit different. | Credit: Nikonians (Click to Enlarge)
The chart above volition give the field of view of only about whatever normal (rectilineal) Nikon lens.
Say you lot want to know field of view of a 35mm lens mounted on an FX body, detect the "Lens Focal Length" column and await down to the row marked "35mm" and then over to the greenish expanse 35mm & FX-format cameras.
The field of view for a 35mm Nikon lens turns out to take a horizontal FOV of 54.5 degrees, 37.8 degrees of vertical range, and 63.4 degrees diagonally. This is the maximum surface area your camera can "come across."
For a 50mm lens on an APS-C/DX sensor, the FOV comes out to 26.3 degrees horizontally, 17.vii degrees vertically and 31.4 degrees diagonally.
Recollect, not all camera manufacturers apply the same sensor size when they refer to "full-frame" or "crop sensor," so the numbers will usually be slightly unlike when using other brands.
Field of View FAQs
What is 'normal' field of view?
A normal field of view is one that looks totally natural to the human eye. For full-frame cameras, this would be achieved with a 50mm lens,
What field of view is 180?
The only camera lens that tin achieve a 180-caste field of view is a super-wide fisheye lens. Be prepared for plenty of distortion, though.
What is the FOV of a 24mm lens?
This volition vary depending on the size of your camera sensor, but in general, the field of view of a 24mm lens will be somewhere around 84 degrees for full-frames, and 61 degrees for ingather sensors.
Does aperture affect field of view?
In general, aperture does not affect FOV.
Final Words
To bring all the technical talk down to how field of view affects your photography world, it tin help yous
- ameliorate understand the visual abilities of any given lens
- cull which lens fits your style of photography
- figure out which lens you'll demand to use when you lot're shooting in a confined space.
The more experience yous get with unlike lenses and shooting in different environments, the more than intuitive the human relationship between field of view and lens focal length will go.
Until then, feel costless to utilise the charts above… and don't forget to have fun!
Source: https://shotkit.com/field-of-view/
Posted by: sanderscoad1958.blogspot.com
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