Here you can see how the 135mm telephoto lens has the narrowest angular field of view at 12 degrees. A 35mm lens has a considerably larger conical visual field with a 46-degree FOV. A focal length of 16mm in with a FOV of 84 degrees.

Beam dumpprice

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 distortion than its wider cousins.

The math behind field of view in photography is a tricky topic, but understanding the concept is pretty simple. This guide breaks it down for you the easy way!

Bumping up to a full-frame sensor, you can see that it takes a longer focal length to get the same angular field of view:

One thing to keep in mind is that inside your camera we’re actually working with circular images. Because your sensor is a rectangle, it captures the rectilinear portion of this cone. That rectangle comprises your field of view.

Extremely high-power beam dumps have been made using water with controlled amounts of colored salts (e.g., copper (II) sulfate) to give a moderate absorbance of the beam. The water is circulated through a long pipe with a window at one end, and chilled using a heat exchanger.

Well, sensor size isn’t standardized. Not only is a full-frame sensor on a Canon camera likely to be a slightly different size than a sensor on a Nikon FX camera, but even next-generation cameras of the same line can employ different sensor sizes.

The most important thing to remember is that shorter focal lengths have a larger angle of view. Conversely, longer focal lengths will have a narrower angle of view. This holds true for both prime lenses and zoom lenses.

Smaller sensors capture a smaller portion of the image cone and therefore have a smaller FOV than a full-frame sensor camera. A medium format camera, having a larger sensor, will have a larger FOV than a full-frame.

NewportBeam Dump

We can also go backwards: if you know your field of view and your sensor size, you can figure out what focal length of lens to use. Pretty nifty, no?

The more experience you get with different lenses and shooting in different environments, the more intuitive the relationship between field of view and lens focal length will become.

For example, shorter lens focal lengths (i.e. 16mm, 24mm, and 35mm) have a larger angular field of view, hence the term “wide-angle” lens.

Put another way, the focal length is simply the distance from the camera sensor to the place where the light rays converge after going through the lens elements.

(Most of the time horizontal FOV is all we need to know. The exception is the example given above where you need to shoot in a very confined area. In that case, you may need to know your field of view exactly.)

Laserbeam Dumpdesign

Speaking of magnification, another important concept to understand when looking at field of view is field size or how much of the subject and background are visible in your camera’s field of view.

The only camera lens that can achieve a 180-degree field of view is a super-wide fisheye lens. Be prepared for plenty of distortion, though.

The angle of view is the angular size of the view cone. (See diagram above.) You might also see it referred to as the angular field of view.

Teryani Riggs (they/them) is an adventure, who loves all things wild and free. Teryani can often be found in the midst of a social/eco-justice campaign, hiking through wild backcountry, or hitchhiking around the world listening to other people’s stories. While their focus has historically centered on landscape, travel, and wilderness photography, they’ve also been hired to shoot genres as varied as historical fiction reenactments in the studio to product and food photography.

Since this equation has the sensor size as one of the factors, it also covers crop factor. (Remember, the smaller the sensor size, the smaller the FOV.)

All of the images above were taken from the same location on a full-frame Sony A7 III. The only thing that changed was the focal length of the lens. Here you can clearly see the differences between the camera FOV.

If the particles in the beam are energetic enough, induced radioactivity, production of neutrons by spalling, radiation embrittlement, and production of secondary particles can also be issues. Considerable quantities of material may be put around the beam dump, especially "downstream" of the beam dump, to serve as radiation shielding. Also, the beam may be carefully not aimed at anything critical (such as people or particle detectors), and angled down into the earth before it hits the beam dump, so that dirt serves as a radiation shield.

The overall field of view is the maximum area your sensor can capture at a given lens focal length of a lens. It’s the lens focal length combined with the size of your camera’s sensor that determines the camera field of view. It is easy to figure out what is field of view of the camera by knowing the focal length.

Some of the calculators even allow you to enter in other variables, too, like the camera distance from the subject, the distance from the subject from the background, etc.

Say you want to know field of view of a 35mm lens mounted on an FX body, find the “Lens Focal Length” column and look down to the row marked “35mm” and then over to the green area 35mm & FX-format cameras.

Wide-angle lenses will expand a perspective, providing a larger field size. Telephoto lenses will compress a perspective, thereby magnifying the subject.

When the FOV is measured in degrees, like on the manufacturer’s lens specs, they’re referring to the angular field of view in the horizontal dimension – from the right to the left edge of the frame. Vertical FOV is measured from the top to the bottom. Diagonal FOV is measured from corner to opposite corner.

On a full-frame camera, a 200mm lens would get a 12-degree FOV, a 50mm lens would come in at 46 degrees, and a 24mm lens would come in at 84 degrees. It would take a 16mm fish-eye to get the full 180-degree horizontal FOV.

A commonly available type of beam dump suitable for most medium-power lasers is a cone of aluminum with greater diameter than the beam, anodized to a black color and enclosed in a canister with a black, ribbed interior. Only the point of the cone is exposed to the beam head-on; mostly, incoming light grazes the cone at an angle, which eases performance requirements. Any reflections from this black surface are then absorbed by the canister. The ribs both help to make light less likely to escape, and improve heat transfer to the surrounding air.

Laserbeam dumpmaterial

So, what is a field of view exactly? Simply defined, field of view (FOV) in photography is the observable world you can see through your camera at any given moment. It’s usually expressed in terms of degrees, referring to the literal angle of view your lens allows your sensor to see. This is the widely accepted field of view definition in photography.

Different camera sensor sizes have innately different fields of view. Smaller sensors will have a narrower FOV. Larger sensors will innately have a wider FOV.

Don’t worry if math isn’t your thing. We’re including a field of view chart down below. This section is really more for those who love to geek out on how things work.

High energy laserbeam dump

A closer look shows us that the angle of view is actually the angle between any light captured on the horizontal dimension, and any light captured at the edge. (The red lines mark the edge.)

This chart covers the focal lengths of normal, rectilinear camera lenses. Fisheye FOV is a bit different. | Credit: Nikonians (Click to Enlarge)

The field of view for a 35mm Nikon lens turns out to have a horizontal FOV of 54.5 degrees, 37.8 degrees of vertical range, and 63.4 degrees diagonally. This is the maximum area your camera can “see.”

Unsurprisingly, many beginner photographers only think about focal length when they go to purchase a new camera lens. In reality, field of view is actually what’s guiding their decision.

For example, if you want a lot of the background included in an image, you’ll want to choose a lens with a larger field of view (and a shorter focal length).

Since 35mm film cameras were the norm back in the 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.

Materials used for such beam dumps include blocks of copper, aluminum, carbon, beryllium, and tungsten. The block often has a long conical hole where the beam hits it, so as to spread the heating over a larger region of the block. If the beam to be absorbed is high powered, these blocks may be up to several meters long and water cooled. Pools of mercury have also been used.

Well, what most of us are doing when buying a lens according to focal length is imagining what field of view it will create. It’s ultimately what determines what kind of lens you’re going to buy.

If you want to go the whole hog and capture a 180-degree view, you’d need a 10.5mm full-frame fisheye lens. That will, of course, give you plenty of distortion, but some actually like the effect.

Camera lenses, with the exception of some fisheye lenses, see much less than that. Knowing just how much of the world your camera will see is a key factor in choosing which lens to use.

Humans have binocular vision, meaning that we see with two eyes, not just one. This allows us to have a fairly wide field of view: 180 degrees, give or take a few degrees of peripheral vision.

“Long lenses” (including telephotos) have longer focal lengths than either a normal or wide-angle lens, and therefore a narrower angle of view. Telephotos, in particular, have a degree of magnification that makes it easier for a subject to upfill more of the frame.

Here’s how to calculate field of view: FOV = 2 * arctan (S / 2f) Where S is the size of the sensor (diagonal size in millimeters) and f is the focal length of the lens (also in millimeters).

The most challenging beam dump design to date is that of the Large Hadron Collider, which must dissipate 725 MJ of beam energy in the 90 μs circulation time, which equates to a power of 8 TW.

Water-cooledbeam dump

It’s also useful to know the field of view if you have a limited space to work in and you need to decide which lens to use. Say, for example, you’re shooting portraits in a small garage and want to use a prime lens. Knowing the FOV will help you know exactly what focal length will work for you.

Of course, you won’t ever have to do the math yourself (unless you want to). There are plenty of field of view charts (like the ones below) and online field of view calculators available.

Let’s take a look at just what field of view is, how it relates to lens focal length, and how it ultimately can guide you in knowing which lenses are best for which situations.

Laserbeamblock

Please note that all of these images were taken on a full-frame camera. Crop-sensor cameras will have a smaller angular field of view using the same focal length.

This is pretty much all there is to it…with the exception of a few adjustments to be made for the distortion of super wide-angle lenses (fish-eyes) and the magnification factor of macro lenses.

Many things in this world go hand-in hand: cookies and cream, peanut butter and jelly, bagels and salmon… In the photography world, we’ve got field of view and lens focal length.

For example, a 200mm lens will enlarge objects 2x more than a 100mm lens does and 4x more than a 50 mm lens does. The field size is the reciprocal, in this case, either 1/2 or 1/4 of the dimension.

Using the image above and the magic of trigonometry, we can calculate the overall field of view with the equation below:

An optical beam dump is an optical element used to absorb a beam of light. Major design concerns in a bump dump typically include the management and reduction of back reflections and scattering as well as the dissipation of heat generated by absorption. For low-power systems and less demanding applications, the device can be as simple as a piece of black velvet or flock paper glued onto a stiff backing, but higher-power beam dumps must often incorporate more elaborate features to avoid back-reflection, overheating, or excessive noise. Dumping the beam with a simple flat surface may scatter unacceptably large amounts of light for some applications, even though the direct reflection may be effectively reduced. To minimize scattering, it is common to use deep, dark cavities lined with an absorbing material to dump the beam. A particularly simple and relatively inexpensive approach is to use a stack of razor blades with the sharp edges facing the beam, so that the spaces between the blades form very deep cavities from which little light escapes.

Focal length, on the other hand, is the same regardless of sensor size – it will always be the distance 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 we get into the longer lenses the level of compression and magnification goes up as well. A little bit can actually be quite flattering in portraits, which is why 100mm, 105mm, and even up to 135mm can be found in a portrait photographer’s lens collection.

The answer is simple: sensor size and lens focal length. Distance from your subject (i.e. “zooming with your feet”) may look like it’s affecting your field of view, but it’s not really changing the angle of view inside your lens.

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.

Beam dumpsizes

This will 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 crop sensors.

If you’re always shooting with the same sensor (i.e. the same camera), then the main thing that will change your field of view is the lens and what lens focal length you choose to use.

A beam dump is a device that absorbs a beam. This may be a beam of photons ("light") such as a laser beam, or a beam of electrically charged particles.

For a 50mm lens on an APS-C/DX sensor, the FOV comes out to 26.3 degrees horizontally, 17.7 degrees vertically and 31.4 degrees diagonally.

The purpose of a charged particle beam dump is to safely absorb a beam of charged particles such as electrons, protons, nuclei, or ions. This is necessary when, for example, a circular particle accelerator has to be shut down. Dealing with the heat deposited can be an issue, since the powers of the beams to be absorbed can run into the megawatts.

Now the confusing thing is that angle of view and field of view are often used interchangeably, and it’s how most manufacturers refer to field of view, but they’re not quite the same thing.

A “normal” lens is one where the FOV looks natural and is more or less what the human eye would expect from an image – there’s no noticeable expansion or compression. The nifty-fifty (50mm) is considered normal in 35mm (full-frame) photography and an 80mm lens hits the mark for those shooting medium format.

To make things that are far away fill your camera’s 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 nice level of magnification. These are the lenses that wildlife and sports photographers favor.

Remember, not all camera manufacturers use the same sensor size when they refer to “full-frame” or “crop sensor,” so the numbers will usually be slightly different when using other brands.

The math behind field of view in photography is a tricky topic, but understanding the concept is pretty simple. This guide breaks it down for you the easy way!

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These lenses also tend to have a level of distortion that needs to be addressed in post-processing, but they capture a large amount of the scene in front of them.

This is determined by the distance between the camera and the subject and the focal length of the lens. A wider field of view will have a larger field size; a narrower field of view will have a smaller field size.

For an image with a “natural” look – one without a lot of distortion or magnification – the FOV offered by a 50mm or even an 85mm lens will do the trick. In fact, 85mm prime lenses are favorites of many portrait photographers.

Note: You only need the (180/π) part if your calculator is working in radians. If yours is working in degrees, leave that part out!