The specular reflection from the blazed grating is different from the flat surface due to the surface structure, as shown in Figure 5. The specular reflection, , from a blazed grating occurs at the blaze angle geometry. This angle is defined as being negative if it is on the same side of the grating surface normal as . Performing some simple geometric conversions, one finds that

Also, since depth of field is best demonstrated with images, you’ll find some depth of field examples, in addition to a depth of field chart to make DOF simple.

As regards the lens size, bigger size/more diameter doesn’t mean brighter. My Sony 20mm f/1.8 is fairly small in diameter and size and it’s much brighter than my big Sony 200-600 mm.

hi thanks a lot for a great information but in the ” Photography – lighting ” book of David Prakel it is written that the smaller size sensor have a lard DOF . which one is correct

As with lenses, there is no such thing as the best camera for depth of field. The camera to use will depend on the DOF effect that you’re seeking. In my case, for example, I always look for a large depth of field in landscape photography (which is the main genre I shoot), so the best camera for me in terms of depth of field is a full-frame sensor camera.

Depth of field (DoF) in photography can be defined as the space in the image that is relatively sharp and in focus. It is the distance between the nearest and farthest elements that are sharp and in focus in your photos.

Guidance , tutorial and discussion is very nice. It’s not understood how to calculate the DOF and Hyperfocal distance from the table. Are Hyperfocal and zone of focusing same? How I prepare the DOF cheat sheet?

Dan, I appreciate you for the great tutorial on DoF. I learned a lot about the principles of digital cameras and images from this site.

In addition to all the information in this depth of field photography guide, I encourage you to go out and shoot as much as you can. That way you’ll know which is the best DOF in each scenario, become familiar with the differences between a shallow vs. large depth of field, and be able to calculate the DOF that you need instantly.

A good DOF tip is to adjust the depth of field before setting the tripod so you can move in case you’re too close to the foreground and need a larger depth of field. You’ll get the result you want if you move according to the depth of field and focusing distance from your main subject.

Depth of field in photography, also known as photography DOF, is one of the key elements you need to know to master the photography basics.

In photography, the aperture is linked to the DoF in your image. To put it simply, the larger the aperture you use, the shallower the depth of field will be. On the other hand, the smaller the aperture you use, the greater the depth of field will be in your image.

So here is the benefit of full frame over apsc body: 1. at the same distance 52mm lens on full frame body give shallower depth of field compare to 35mm lens on APSC body. 2. bigger sensor + bigger lens size 52mm allow more light compare to smaller sensor + smaller lens (I assume here 35mm lens is smaller than 52mm lens in glass size which not always the case with zoom lens line 70-200mm)

Both the reflective and transmission gratings suffer from the fact that the zeroth order mode contains no diffraction pattern and appears as a surface reflection or transmission, respectively. Solving Eq. 2 for this condition, = , we find the only solution to be =0, independent of wavelength or diffraction grating spacing. At this condition, no wavelength-dependent information can be obtained, and all the light is lost to surface reflection or transmission.

i think its ever best photography course I already searching 6 months in all platforms like YouTube but i have not seen this kind of explanation

Reflective grating master copies are made by depositing a metallic coating on an optic and ruling parallel grooves in the surface. Thorlabs' reflective gratings are made of epoxy and/or plastic imprints from a master copy, in a process called replication. In all cases, light is reflected off of the ruled surface at different angles corresponding to different orders and wavelengths. All of Thorlabs' ruled reflective diffraction gratings exhibit a sawtooth profile, also known as blazed, while our reflective holographic diffraction gratings exhibit a sinusoidal profile. For more information, please refer to the Gratings Tutorial tab.

A shallow depth of field is controlled by a series of elements that you’ll find below, with aperture being the most important (the larger the aperture, the shallower the depth of field).

What does depth of field mean? Depth of field, also known as DOF, is defined as the amount of the image that is considered sharp and in focus. What is a shallow depth of field? A shallow depth of field is a small amount of the image in focus. When using a shallow depth of field, the area in focus between the closest and the farthest element is very narrow. Where is the depth of field preview button? The depth of field preview button is located on the top-right front of most digital cameras, usually around the camera lens mount. What factors affect depth of field? Depth of field is determined by the lens aperture, the focal length, the focusing distance, and the sensor size. What is the best depth of field for landscape photography? The best depth of field in landscape photography is usually a large depth of field in order to make the portion of the image in focus as large as possible. Wide-angle lenses are the best lenses for taking a large depth of field image. What is the best depth of field for portrait photography? The best depth of field for portraits is a shallow depth of field when you want your subject to stand out from the background. Fast lenses with f-stops below f/2.8 are the best for taking a shallower depth of field and bokeh.

In this case, you can see an example of shallow depth of field in portrait photography. Using the biggest possible aperture, we can focus the attention on our subject, leaving the rest of the scene out of focus.

The Littrow configuration refers to a specific geometry for blazed gratings and plays an important role in monochromators and spectrometers. It is the angle at which the grating efficiency is the highest. In this configuration, the angle of incidence of the incoming and diffracted light are the same, = , and > 0 so

The best lens for depth of field depends completely on the scene that you want to capture. For example, the best lenses for a shallow depth of field are usually telephoto and fast lenses that offer a wide aperture.

The blazed grating, also known as the echelette grating, is a specific form of reflective or transmission diffraction grating designed to produce the maximum grating efficiency in a specific diffraction order. This means that the majority of the optical power will be in the designed diffraction order while minimizing power lost to other orders (particularly the zeroth). Due to this design, a blazed grating operates at a specific wavelength, known as the blaze wavelength.

A shallow depth of field is considered a short focus; that is, the line between the nearest and farthest elements that are sharp and in focus is very short, or, in other words, there’s a small portion of your image in focus.

*Please note that we’re considering the same focal length in this depth of field comparison. If we consider the same field of view, the depth of field will be narrower in cameras with larger sensors and larger in cameras with cropped sensors.

The blaze wavelength is one of the three main characteristics of the blazed grating. The other two, shown in Figure 3, are , the groove or facet spacing, and , the blaze angle. The blaze angle is the angle between the surface structure and the surface parallel. It is also the angle between the surface normal and the facet normal. Note that Figure 3 also defines the direction of the "blaze arrow"; this arrow is visibly marked on one edge of all Thorlabs' blazed transmission gratings.

Depth of field and distance are also two inseparable elements. The closer you are to the subject that you want to shoot, the shallower the depth of field will be, whereas the further you are from the main element, the greater the depth of field will be in the image.

Please note that dispersion is based solely on the number of grooves per mm and not the shape of the grooves. Hence, the same grating equation can be used to calculate angles for holographic as well as ruled blazed gratings.

When you shoot using telephotos, you can see examples of a small depth of field in landscape photography, like in the picture below. Despite the fact that I used a narrow aperture, only the foreground is acceptably in focus.

One popular style of grating is the transmission grating. The sample diffraction grating with surfaces grooves shown in Figure 1 is created by scratching or etching a transparent substrate with a repetitive series of narrow-width grooves separated by distance . This creates areas where light can scatter.

I came across this while looking for examples to show my kids about DOF; even experienced photographers can learn a thing or two from this. Thank you for the well-written and well-illustrated article.

Beyond the theory, depth of field is best demonstrated with examples, so below you’ll find a DOF comparison of different depth of field images.

Resolving Power:The resolving power of a grating is a measure of its ability to spatially separate two wavelengths. It is determined by applying the Rayleigh criteria to the diffraction maxima; two wavelengths are resolvable when the maxima of one wavelength coincides with the minima of the second wavelength. The chromatic resolving power (R) is defined by R = λ/Δλ = n*N, where Δλ is the resolvable wavelength difference, n is the diffraction order, and N is the number of grooves illuminated. Due to their low groove density, Echelle gratings provide high resolving power.

Another very common diffractive optic is the reflective grating. A reflective grating is traditionally made by depositing a metallic coating on an optic and ruling parallel grooves in the surface. Reflective gratings can also be made of epoxy and/or plastic imprints from a master copy. In all cases, light is reflected off of the ruled surface at different angles corresponding to different orders and wavelengths. An example of a reflective grating is shown in Figure 2. Using a similar geometric setup as above, the grating equation for reflective gratings can be found:

Stray Light:Due to a difference in how the grooves are made, holographic gratings have less stray light than ruled gratings. The grooves on a ruled grating are machined one at a time which results in a higher frequency of errors. Holographic gratings are made through a lithographic process, which generally creates smoother grating masters free of tool marks. Replicants made from these masters exhibit less stray light. Applications such as Raman spectroscopy, where signal-to-noise is critical, can benefit from the limited stray light of the holographic grating.

As you can see, understanding depth of field in photography is crucial in order to achieve your photographic goals. Adjusting and controlling the DOF, you’ll make sure that everything in your images is as sharp and focused as you want it to be.

In this case, the shorter the focal length, the larger the depth of field will be, whereas the longer the focal length, the shallower the depth of field. Following this logic, the depth of field in a 50 mm lens will be shallower than the DOF in a 35mm lens.

where both and are positive if the incident and diffracted beams are on opposite sides of the grating surface normal, as illustrated in the example in Figure 1. If they are on the same side of the grating normal, must then be considered negative.

The blazed grating features geometries similar to the transmission and reflection gratings discussed thus far; the incident angle () and th order reflection angles () are determined from the surface normal of the grating. However, the significant difference is the specular reflection geometry is dependent on the blaze angle, , and NOT the grating surface normal. This results in the ability to change the diffraction efficiency by only changing the blaze angle of the diffraction grating.

where is positive and is negative if the incident and diffracted beams are on opposite sides of the grating surface normal, as illustrated in the example in Figure 2. If the beams are on the same side of the grating normal, then both angles are considered positive.

The DCG film is taken through multiple quality control steps to ensure it performs up to standard and then cut into the desired size. The film is sealed between two glass covers to prevent degradation of the material. Since the DCG film is contained between two glass substrates, VPH gratings have high durability and long lifetimes, as well as easy maintenance compared to other gratings that can be easily damaged.

Most of the examples of depth of field in landscape photography are deep DoF, like in the image below. To keep everything in focus, you need to use small apertures and keep the distance from the main elements of the scene under control.

Shallow depth of field is also known as a short depth of field or narrow depth of field. The important thing is to understand what exactly is a shallow depth of field and, especially, when you should use a shallow depth of field.

Diffraction sheetcost

Holographic gratings are made from master gratings by similar processes to the ruled grating. The master holographic gratings are typically made by exposing photosensitive material to two interfering laser beams. The interference pattern is exposed in a periodic pattern on the surface, which can then be physically or chemically treated to expose a sinusoidal surface pattern. An example of a holographic grating is shown in Figure 9.

The Littrow configuration angle, , is dependent on the most intense order ( = 1), the design wavelength, , and the grating spacing . It is easily shown that the Littrow configuration angle, , is equal to the blaze angle, , at the design wavelength. The Littrow / blaze angles for all Thorlabs' Blazed Gratings can be found in the grating specs tables.

Once you know what depth of field is and understand the DOF definition, the next step is knowing which is the best DOF in photography and how you can adjust the depth of field to achieve your goals.

Polarization Dependence:Surface gratings that have high groove densities also have an issue with polarization dependent loss, often with significantly lower efficiency when exposed to parallel- versus perpendicularly-polarized light. Volume phase holographic gratings are designed for applications that require low polarization dependent loss at higher spatial frequencies.

The desired grating pattern is comprised of a repetitive series of lines separated by distance . The fringe planes for transmission gratings are perpendicular to the plane of the plate as seen in Figure 8, allowing any frequency of light to pass through the plate. Diffraction occurs as incoming light crosses through the DCG film. Therefore, the three major factors that determine performance are film thickness, bulk index (the average index of refraction between Bragg planes), and index modulation (the difference of index of refraction between the Bragg planes). The incident light enters the grating at an angle of , as measured from the surface normal. The light of order exiting the grating leaves at an angle of , relative to the surface normal. The grating expression mentioned above can be used to calculate diffraction angles for volume phase holographic gratings since dispersion is based on the line density. The quality of the grating is determined by the fringe contrast, with a poor fringe contrast resulting in low efficiency or no grating at all.

In my opinion, depth of field calculator apps are a good way to understand depth of field in photography, but once you practice and shoot for a while, you’ll learn how to calculate the depth of field spontaneously.

The depth of field preview button is located on the top-right front of most digital cameras, usually around the camera lens mount.

Figure 6 illustrates the specific case where = 0°, hence the incident light beam is perpendicular to the grating surface. In this case, the 0th order reflection also lies at 0°. Utilizing Eqs. 3 and 4, we can find the grating equation at twice the blaze angle:

Diffraction sheetnear me

You’re right, the sensor size doesn’t affect the DOF when you view it at the same focal length, same aperture and same distance.

Blaze Wavelength:Ruled gratings have a sawtooth groove profile created by sequentially etching the surface of the grating substrate. As a result, they have a sharp peak efficiency around their blaze wavelength. Holographic gratings are harder to blaze, and tend to have a sinusoidal groove profile resulting in a less intense peak around the design wavelength. Applications centered around a narrow wavelength range could benefit from a ruled grating blazed at that wavelength.

This issue can be resolved by creating a repeating surface pattern, which produces a different surface reflection geometry. Diffraction gratings of this type are commonly referred to as blazed (or ruled) gratings. More information about this can be found in the section below.

And last, but not least, knowing how to focus in photography and what are the focus modes and areas is crucial to get the pictures you want. You can get all this information by downloading my PDF photography basics guide.

known as the grating equation. The equation states that a diffraction grating with spacing will deflect light at discrete angles (), dependent upon the value λ, where is the order of principal maxima. The diffracted angle, , is the output angle as measured from the surface normal of the diffraction grating. It is easily observed from Eq. 1 that for a given order , different wavelengths of light will exit the grating at different angles. For white light sources, this corresponds to a continuous, angle-dependent spectrum.

This is a great example of a shallow depth of field. Using a small aperture and getting closer to the subject, I could focus on the glass with the logo, leaving the other glasses out of focus.

This part need to correct: “In APS-C cameras, for example, the sensor size is cropped, which means that normal focal lengths have a multiplication factor x 1.5. As we explained above in the focal length vs. DOF section, a 35 mm in a full-frame camera is roughly a 52 mm focal length in an APS-C camera, which means that the depth of field will be narrower in the cropped-sensor camera.”

As you can see, the F-stop and the depth of field will be responsible for creating whatever amount of your image is in focus. There are other elements that affect DOF, but as a depth of field photography tip, before thinking about other settings of the exposure triangle, adjust your aperture first according to the depth of field and the elements in your image that you want in focus.

Checking our guide to aperture in photography and our guide to camera sensor size is a good way to complement all the depth of field basics and examples.

Unlike traditional gratings, volume phase holographic (VPH) gratings do not have surface grooves. Instead, VPH gratings consist of a dichromated gelatin (DCG) film between two glass substrates. These VPH gratings are designed to reduce the periodic errors that can occur in blazed gratings. Surface gratings with high groove density also have an issue with polarization dependent loss. These unique transmission gratings deliver high first-order diffraction peak efficiency, low polarization dependence, and uniform performance over broad bandwidths.

On the other hand, the best lenses for having a large depth of field are wide-angle lenses, since you can focus at the hyperfocal distance and have practically your entire image in a reasonable focus.

Understanding depth of field is essential for having all the important elements that you want in your image in focus, but before diving into that, let’s get familiar with the most common depth of field terminology.

While blazed gratings offer extremely high efficiencies at the design wavelength, they suffer from periodic errors, such as ghosting, and relatively high amounts of scattered light, which could negatively affect sensitive measurements. Holographic gratings are designed specially to reduce or eliminate these errors. The drawback of holographic gratings compared to blazed gratings is reduced efficiency.

The reason for this is physical. If you think about a wide-angle lens, all the elements in the far distance are smaller and, therefore, it’s easier to focus on everything, whereas in longer focal lengths like telephoto lenses, there is a relationship between magnification and depth of field; the elements in the far distance will be larger and, consequently, it’ll be more difficult to focus on a large area.

In APS-C cameras, for example, the sensor size is cropped, which means that normal focal lengths have a multiplication factor x 1.5. As we explained above in the focal length vs. DOF section, a 35 mm in a full-frame camera is roughly a 52 mm focal length in an APS-C camera, which means that the depth of field will be narrower in the cropped-sensor camera.

It is easily observed that the wavelength dependent angular separation increases as the diffracted order increases for light of normal incidence (for = 0°, increases as increases). There are two main drawbacks for using a higher order diffraction pattern over a low order one: (1) a decrease in efficiency at higher orders and (2) a decrease in the free spectral range, , defined as:

In this guide to depth of field in photography, you’ll find everything you need to know about this topic: What affects depth of field? What is the best DOF? Should I use a shallow depth of field? All explained in a simple way so you can understand what is depth of field in photography and how it works.

The 0th order reflection from a blazed grating is shown in Figure 4. The incident light at angle is reflected at for = 0. From Eq. 3, the only solution is = –. This is analogous to specular reflection from a flat surface.

To calculate the DOF and hyperfocal distance, you can use any chart or app (I suggest the last option), and inserting your camera model, aperture, and focal length, you’ll get the focusing distance that maximizes your depth of field. The hyperfocal distance is simply that, a distance to which you direct your focus point 😉

Efficiency:Ruled gratings generally have a higher efficiency than holographic gratings. Holographic grating tend to have a lower efficiency but a broader effective wavelength range. The efficiency of ruled gratings may be desirable in applications such as fluorescence excitation and other radiation-induced reactions.

There are some exceptions and examples of large depth of field in wildlife photography; this is one of them. The goal was to have everything in focus so the grizzly bear could be integrated into the landscape, so I decided to get closer in order to use a shorter focal length and close the aperture.

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Please bear in mind that we’re considering the focal length, not the field of view. For that reason we mention the following note in the article: “*Please note that we’re considering the same focal length in this depth of field comparison. If we consider the same field of view, the depth of field will be narrower in cameras with larger sensors and larger in cameras with cropped sensors.”

The first issue with using higher order diffraction patterns is solved by using an Echelle grating, which is a special type of ruled diffraction grating with an extremely high blaze angle and relatively low groove density. The high blaze angle is well suited for concentrating the energy in the higher order diffraction modes. The second issue is solved by using another optical element: grating, dispersive prism, or other dispersive optic, to sort the wavelengths/orders after the Echelle grating.

A large depth of field is also known as deep depth of field or great depth of field, and it’s caused by different elements, with focal length being one of the most important. As an example, wide-angle lenses allow a greater depth of field.

The best depth of field in landscape photography is usually a large depth of field in order to make the portion of the image in focus as large as possible. Wide-angle lenses are the best lenses for taking a large depth of field image.

To know which is the best depth of field in your photography, the first essential thing is to learn the main factors that affect depth of field so you can adjust the DOF in your images later according to your taste and goals.

For further information about gratings and selecting the grating right for your application, please visit our Gratings Tutorial.

In photography, there is no such thing as the best depth of field; it depends entirely on the subject that you’re photographing and your artistic goals. For example, most landscape photographers aim at having the biggest possible area of their images in focus, and, therefore, they use a deep depth of field. However, when shooting a portrait, it’s common to have the background be out of focus, something that’s also known as “bokeh” effect, which is the result of using a shallow depth of field.

It’s common to see examples of small depth of field in wildlife photography, since this genre is usually shot using telephoto lenses and small apertures. In this case, everything was out of focus except the main subject.

Great posts all over this site! The visual breakdowns and infographics you’ve put together are really helpful. Thank you, this all seems like it was quite a lot of work to put together!

You can also “break the rules” to increase your depth of field by doing a focus stacking. This is, however, a more advanced technique that I don’t recommend doing if you are still starting out in photography.

Don’t forget to save and keep the depth of field cheat sheet with you, and don’t hesitate to leave any questions related to depth of field in the comments!

Diffraction gratings, either transmissive or reflective, can separate different wavelengths of light using a repetitive structure embedded within the grating. The structure affects the amplitude and/or phase of the incident wave, causing interference in the output wave. In the transmissive case, the repetitive structure can be thought of as many tightly spaced, thin slits. Solving for the irradiance as a function wavelength and position of this multi-slit situation, we get a general expression that can be applied to all diffractive gratings when = 0°,

Conversely, in this other example of depth of field in portrait photography, the DoF is large, since we want to include the subject in the landscape. Another example would be to shoot a portrait of a group of people where we want to have everyone in focus.

Thorlabs offers two types of transmission gratings: ruled and volume phase holographic. The ruled transmission gratings are created by scratching or etching a transparent substrate with a repetitive, parallel structure, creating areas where light can scatter. These gratings have a sawtooth diffraction profile and are made of epoxy and/or plastic imprints from a master copy, in a process called replication. Our volume phase holographic diffraction gratings consist of a dichromated gelatin (DCG) film between two glass substrates. These gratings have a sinusoidal wave diffraction pattern written on the DCG film using a laser setup. For more information, please refer to the Gratings Tutorial tab.

Focal length is physical property of lens that will never change despite of the camera body crop sensor or full frame. Change in field of view won’t change focal length.

The sensor size doesn’t affect the DOF when you view it at the same magnification, same focal length, same aperture and same distance. The problem is that to have the same framing to compare it, you need to decrease the focal length of the smaller sensor or increase the distance of the subject. That’s when you’ll see the difference: slightly larger DOF with the crop sensor.

The best depth of field for portraits is a shallow depth of field when you want your subject to stand out from the background. Fast lenses with f-stops below f/2.8 are the best for taking a shallower depth of field and bokeh.

Caution for Gratings with Surface Grooves:The surface of a diffraction grating with surface grooves can be easily damaged by fingerprints, aerosols, moisture or the slightest contact with any abrasive material. Gratings should only be handled when necessary and always held by the sides. Latex gloves or a similar protective covering should be worn to prevent oil from fingers from reaching the grating surface. Solvents will likely damage the grating's surface. No attempt should be made to clean a grating other than blowing off dust with clean, dry air or nitrogen. Scratches or other minor cosmetic imperfections on the surface of a grating do not usually affect performance and are not considered defects. Conversely, volume phase holographic gratings can be cleaned using standard optics cleaning procedures and have high durability.

To understand the meaning of depth of field better, it is the amount of the image that is acceptably in focus. For example, think about photographing two subjects that are at different distances from you. If only what is between one subject and the other is sharp, but everything else is blurred, the distance between the two subjects would be the definition of depth of field.

Considering we’re using the same focal length, the larger the sensor size, the larger the depth of field, and the smaller the sensor size, the narrower the depth of field you’ll see.

That said, it’s fundamental that you understand the depth of field factors and which depth of field to use depending on the situation and the subject that you’re shooting. Also, it’s crucial to understand focusing in photography and what are the focus areas and modes.

The best way to calculate the depth of field is to use a depth of field calculator in an app or a depth of field calculator online like this one.

A shallow depth of field is a small amount of the image in focus. When using a shallow depth of field, the area in focus between the closest and the farthest element is very narrow.

Conversely, a large depth of field is a greater depth of field, which means that a larger amount of the image is in focus. In this case, the line between the nearest and farthest elements that are reasonably sharp is long.

In this case, you can see an example of a large depth of field. The focal length was too long, considering the short distance from the foreground, so I had to close the aperture to increase the depth of field.

Depth of field is so important because it’s related to the sharpness of your photograph, and it’ll completely affect the way you see the final picture.

The incident light impinges on the grating at an angle , as measured from the surface normal. The light of order exiting the grating leaves at an angle of , relative to the surface normal. Utilizing some geometric conversions and the general grating expression (Eq. 1) an expression for the transmissive diffraction grating can be found:

Some of the best depth of field calculator apps for iPhone and Android are Photopills and Depth of field calculator. On these apps, you can enter your depth of field camera settings, and they’ll provide the hyperfocal distance and depth of field chart.

I’m sorry, but the part about the sensor size and DOF is just wrong. Considering we use the same lens and same distance to the subject, only swapping the camera on the back, the DOF will not change, only the field of view. DOF changes only between sensor sizes on the same lens, when you adjust your distance to subject to adjust for the framing.