How Does A Dslr Camera Work

By | 24/10/2022

A camera lens is arguably the well-nigh important function of a photographers set-up, to the point where most professional person photographers would rather shoot with an ok camera body as long as they had a tiptop-quality lens rather than the other way around. Yet, if you are just entering the earth of DSLR lenses, at kickoff glance they tin be a bit overwhelming. Exactly what do all those numbers and letters on the side mean? Which lens should I go and exactly how do they work?


It may seem like magic, merely it is actually pretty uncomplicated. Read on.

Choosing the right lens can make or intermission the image that you are trying to capture. This is because the lens is the office of the camera that controls the image which is projected onto the cameras sensor. Without a lens you lot would only be able to capture white light, which is non much utilize to anyone really.

To be able to confidently choose the right lens for whatever particular photographic situation, an agreement of how a DSLR lens actually works will be invaluable. Once you can decipher the code-like inscriptions on each lens, choosing which lens to get from the vast selection each camera manufacturer produces will become less of a headache.

What Is A Camera Lens?

The lens of any camera is simple a tool which is able to focus calorie-free on a fixed bespeak. In DSLRs this stock-still signal is the digital paradigm sensor. To do this the bodily lens looks like a tube and contains multiple drinking glass plates which are either curved inwards (concave) or outwards (convex). Each blazon of lens will contain a differing number and organisation of drinking glass plates to enable y’all to capture images in different situations.  These lens elements basically serve to curve low-cal in unlike ways.

The Beefcake of a DSLR Camera Lens

The scientific discipline that makes a camera lens work is actually pretty cool. If y’all call back back to your school days when you did those little experiments where you would split white light into its different visible colours using a prism, well a lens is a more complicated version of that.

In general, you do not need to worry nearly the inside of a lens. There are not any serviceable parts to worry well-nigh. All the same, to actually understand how a lens works its important to have an thought of what actually makes upwards a DSLR lens.

At the front end of the lens yous have the front element and and then at that place is another element all the manner at the rear. These two elements basically protect the rest of the stuff within the lens. Between the two elements you will find the lens group. This is the series of concave and convex glass plates which assistance focus the lite. Inside the lens you lot will also find the aperture, which is the role of the lens which controls the adaptable opening that lets the calorie-free in.

Reflex camera simple labels

When you expect through the viewfinder on a dSLR (digital single lens reflex) camera or an SLR (single lens reflex camera), you meet the image equally it is being modified by the glass elements of the lens.  On mirrorless cameras, at that place is no mirror to reverberate this epitome upward into the viewfinder, which allows these cameras to be smaller and lighter.

Below is a cutaway photograph of a Pentax 1.4 lens using fluorescence laser imaging clearly showing the 9 glass elements inside this particular lens.

Laser Fluorescence Cutaway of Pentax Lens

Some of these parts will be fixed and some may move to assist focus, zoom, and stabilize the epitome. The moveable, stock-still and arrangement of parts changes from lens to lens.

The outside of the lens as well has several different parts to information technology and once again tin alter from lens to lens and betwixt manufacturers. At the front of the lens you have the filter thread where you adhere a circular filter followed past the lens hood mounting groove where the lens hood/shade can exist attached.

Lens hoods are important especially in sunny environments.  They help forbid flare and other unwanted effects from stray light beams.

Filter threads let you to use any of a variety of filter types, whether its uv or polarizer, etc.  Filters come in different sizes based on the bore of the lens.  They tin can be as modest as 50mm and larger than 100mm.  Because spiral on filters are not quick to have off and have to be purchased in the exact size for your lens, foursquare filters of a single size which utilize filter holders mounted on the lens are also popular, although more so in studio settings where dust and elements are not much of an issue.

Many photographers use a uv filter on whatsoever lens, especially an expensive one, to protect the lens when it bumps into something difficult, whether its from cracks or scratches.  I’ve personally had times when the lens hit a difficult sharp object and my cheap uv filter shattered.  It would have been much worse if that happened to the front element of the lens itself.


In the middle of the lens trunk at that place are several dissimilar settings and parts including the focus ring, zoom ring, lens specification markings, depth of field indicators, aperture band and image stabilisation controls. At the back of the lens you will detect the lens mount where you lot attach the lens to the camera torso (which you lot want to make sure is of the correct blazon for the camera). Y’all may as well find a “MF/AF” switch which allows you to switch between transmission and automatic focusing of the lens.

Distance indicators show in anxiety and meters what distance you are to your subject.  Not so much anymore with DSLRS, simply in the past this was of import when everything was done manually and you had to calculate hyperfocal altitude etc.

The letters “USM”  represent an ultrasonic motor and these lenses are preferrred by many due to the fact that the motors are faster to focus and quieter.  They can also be labeled as “HSM”, or high speed motor.

The letters “DX” on a camera lens stand for crop sensor lenses, discussed later in this commodity.  DX is a Nikon designation while EF-S is the one on Canon lenses.

The letters “Asph” stand for aspherical lenses,  and they basically mean some of the lenses are not spherical (only like asymptomatic ways without symptoms), which helps in limiting aberrations.

Image stabilization markings are a bit confusing to some.  VR stands for vibration reduction, IS for image stabilized, and OIS for optical prototype stabilization.  Optical prototype stabilization is better than digital paradigm stabilization and it involves a an actual floating drinking glass element and not simply digital paradigm processing.

Stabilization is a great feature and a actually clever thing really.  It allows you to photograph up to 2 stops slower, so y’all no longer need to shoot at the minimum recommended shutter speed of 1/125 second.  It basically uses sensors and motors to counteract your shaky easily or other small movements.  It is not made for large movements.

The lens mount is where the lens connects to the camera and holds it securely in place without letting in dust or dirt.  These are mostly of the bayonet blazon at present.  Each manufacturer such every bit Sony, Nikon, Catechism, etc has their own lens mount.   Adapters, discussed later on, allow one to apply lenses fabricated for ane brand of photographic camera on another make body.

Some lenses such as fisheye ones actually have filter mounts at the dorsum of the lens, since the large curvature of the lens does not allow a flat filter to be mounted up front.

How Does A DSLR Lens Piece of work?

Quite just, the series of glass plates within the lens tube allow the low-cal to be focused on the digital image sensor which then records the lite as an image.


The lens forms an epitome of the field of study that we are trying to have a photo of on the camera sensor. At present lets go a little technical for a minute.  Don’t worry, its non too complicated and will give y’all a amend understanding of how lenses work.

As light moves through a convex lens  and forms an prototype, it is afflicted by the angle of entry too equally the glass lens construction itself.  When the subject altitude to the lens is modified, the angle of light entry changes every bit well.  The image of a discipline which is far abroad from the lens forms closer to the lens and vice versa.

Lens powerThick convex lenses (with a large belly)  in plough make light bend at a sharper angle since the distance betwixt various points on the lens is increased.  Every bit a result, light will converge closer to the lens.  If the convex lens is thinner, the prototype is formed farther from the lens.  This results in an increase in the size of the image.


When y’all focus a lens, whether manually or automatically, y’all move some of the lens elements further or closer to the camera sensor (or in the case of SLRs, motion picture).  This alters how light is bent by the lens and relocates the position where light rays converge.  You practise this until you lot find a point where the object you want to be in focus is precipitous, meaning where the light rays converge where the sensor or movie is.  Manual focus is what used to be the norm for years.  Now autofocus and autofocus with manual aligning has been popularized, and for good reason.

Although not perfect, focusing technology has allowed focusing to be much faster for action photography than us manually turning the band, and many times this may hateful the difference between a sharp image or a blurry missed opportunity.  In another conditions where we cant encounter well such as in dim low-cal, the digital sensors may exist meliorate than our optics.


Autofocus is an interesting feature.  Other than having different options such as continuous or single autofocus (which usually has a selector switch and i of which using more bombardment), information technology works by the camera sending signals to the lens and vice versa.  When the indicate that the image is sharper after a focus attempt is fabricated is sent back, the camera knows in which management to turn the virtual focus ring.  This procedure is repeated until focus is accomplished, and it is much faster than i merely described.

Another thing you lot may have noticed is some lenses go longer or shorter equally you focus while others practice not.  The divergence is internal vs external focusing.

Focal Length

This length is actually calculated when the lens is focused at infinity. But what does that actually mean? Well, when light travels through your camera it is flipped upside downwards. The indicate where the image is flipped (where the light converges) is known equally the nodal point. The distance from that bespeak to the image sensor is the focal length.

This is literally how far it is between the point at which the light converges to form a sharp image of the thing you are photographing and the image sensor. It is unremarkably measured in millimeters (mm) and will exist clearly marked on the lens.

The focal length lets us know how much of the scene that we meet before us volition be captured and how large, or magnified, the parts of the scene will be. The longer the focal length the more than “zoomed in” the image will be. Whereas shorter focal lengths allow you lot to capture a much wider view with less magnification.

Focal length of a lens is what yous see when you get to buy a lens- information technology is both the magnification of a particular lens and the distance between a lens and the created image.  So a 1000mm lens will magnify much more than a 100mm lens.  If you desire a relatively neutral lens yous tin get with one that has a focal length of 50mm.  The bodily resulting prototype too will depend on whether you have a full frame or crop photographic camera, and as the proper noun suggests, it is non because of the magnification.

Crop sensors/ cameras seemingly increase the focal length of the lens considering of this cropping.  As an example, Nikon APS-C sensors have a 1.5x magnifier, so if yous attach the same lens to such a camera, the image will be ane.5x larger than if y’all attached the same lens to a total frame photographic camera, something you lot may want for details of birds simply not for wide shots of landscapes.

This multiplier will give you what is called the equivalent focal length.  That mode you can find out what lens you will demand to utilize on your item type of camera ingather as compared to someone else’south setup with a dissimilar blazon of camera.

Full frame sensors are equal to the size of 35mm flick or 24mm 10 36mm.  Crop frame sensor ways any size sensor smaller than the 35mm film frame.  Ingather frame sensors crop out the outer edges of the frame, meaning that you do not run across what would be in the image at the periphery.

Full frame lenses cost more and weigh more because they are higher quality.  So exercise full frame cameras.  There are too more lenses made for full frame cameras considering many photographers prefer them.

Back to lenses,  more convex lens element gives a wider angle and a shorter focal length (for example 35mm).  A telephoto lens with a flatter glass element gives you a narrower angle and a longer focal length (for case 200mm).

The very first lenses only had a single focus length (known today equally prime lenses) until some pretty clever people thought it would be absurd if you could have one lens that would be able to take photos of things that were shut up and far away. They came up with a fashion to exist able to modify the configuration of the lens group and and then change how close or far away the nodal point was from the paradigm sensor. This is how the “zoom lens” was born.



is one of those photographic terms that sounds really technical and tin can accept a little while to go your caput around. Still, once yous do, choosing a lens and getting the shot you desire volition become a whole lot easier and more fun!


The aperture relates to how big the opening is that lets light in. Think of it like the iris (the coloured bit of the eye) that controls how large or small the pupils are. The aperture is expressed in


and  (confusingly) the smaller the number, the larger the opening. For example, a lens which has an f-stop of f/2.viii will have a larger opening so let in more calorie-free than a lens with an f-stop of f/xi.

F-stops have a funny proper noun that many people don’t even know the meaning of.  It is actually related to the focal length which I discussed earlier.  F-Stops are simply fractions of the focal length.  The style these fractions piece of work is every bit follows:  Let’southward say y’all accept a 300mm f2.eight lens (a nice bright lens).  If you are set up up to shoot at f2.viii aperture, nosotros simply separate the 300mm focal length past 2.viii and get 107mm.  This is the size of the opening in your lens.

The discontinuity also effects the depth of field in an image, or whether the whole image is sharp and in focus or not. When you go with a loftier number f-stop, you will be letting in less light and accept a deeper depth of field.  When you go with a low number f-cease, you will be letting in more than calorie-free and have a shallower depth of field.

Adjusting this parameter will help you to create those cool looking portraits where just the person is in focus and the groundwork is blurry. A larger opening (or smaller f-stop number) will allow you to create this. Whereas a smaller opening (or larger f-stop number) will allow you to have more of the image in focus which is cracking for landscapes.


The lens’ discontinuity is the other code-similar inscription you will detect on your lens. The f-stop number that is listed on the lens next to the focal length will be the maximum aperture. A lower maximum f-end number (and so wider opening) will mean that the lens volition be better in low-light situations. So, if night or natural light (no flash) photography is your thing and then this is definitely something to consider.

A low f-finish number is besides an indication of the quality of the lens. Top-quality lenses volition have a constant f-end through the focal range every bit opposed to lower quality lens (and lower price) which will have a f-stop which varies as you lot motion through the focal range (like 3.5-five.6). In this instance you will probably lose around i stop of low-cal as you lot travel up the focal length from a broad angle to telephoto.  These are called variable discontinuity lenses while the others are sometimes called stock-still aperture lenses.

Considering of the parts and mechanics involved,  variable aperture lenses are larger and heavier.  Some camera systems exercise not take an aperture built into the lens but that is rare and they require special lenses.

Here’s Recollect Media’southward explanation that may help understand all this and become into some more than particular:

Camera Lenses and Camera Bodies

Photographers ever talk about their collection of “glass” more than than photographic camera bodies themselves. Cameras come up and go.  Lenses concluding longer.  This has some limitations of course.  While people are still using “bulletproof”  Nikon lenses from the 1970s and 1980s, which are both cheap and of good quality, they have their limits.  Many are manual focus, many with autofocus have been used for many years and may exist worn out, including what powers them, lens mounts, connectors, etc.  But you tin can nonetheless find barely used lenses that

This is not to say there are not neat  DSLR lenses coming out every year because there are.  While they may not have many new features (in that location are only and so many features a lens tin can have), as technology changes they go lighter, better performing, or less costly.  While you lot may be able to go a small lightweight 50mm prime lens for around $100 that gives really nice quality images for apprentice photographers, it will never supersede a 100-300 mm optically stabilized single focal length lens.

Just make sure that when y’all starting time your lens collection, y’all do not autumn into the trap of buying lenses with many unlike mounts, such equally Nikon or Canon.  You want to stick to one lens mountain, for case Nikon, and utilize adapters that allow other make lenses such as Canon on your camera.  These adapters are getting better every year, and while they may only give mechanical functions using a 1970 Nikkor lens, with mod lenses they may give you autofocus, light and other readings.

Adapters should not exist dislocated with tele-converters or macro rings.  These do non accommodate to dissimilar mounts just rather affect the way the lens behaves.  Teleconverters have an optical element with a magnification factor which increases the total magnification/focal length, although causing loss of light due to the actress optical element.

Macro extension rings on the other hand are just spacers which let you to put your subject much closer to the lens and notwithstanding have focus.  This is because the focusing range of your lens in decreased, no longer existence able to focus at infinity.

Camera bodies are besides replaced often (besides the fact that shutters dont last forever) because camera technology evolves so speedily.  Camera manufacturers are in a high level of competition every twelvemonth putting out new models that are ameliorate than last years, whether its the sensor, bombardment life, megapixel count, etc. Don’t forget that every time your camera body gets improve, your existing lenses will also give you ameliorate photos when used along with it.

What you should keep in mind when buying new lenses if you are serious virtually photography due to what i described and so far is you should purchase good quality lenses with quality features, such as a depression number fixed aperture.  They will terminal if you accept intendance of them, and y’all volition be able to use them on unlike photographic camera bodies.

While im on the topic of budget, third party lens manufacturers such as Sigma, Tamron and Tokina make lenses for other camera brands and these can relieve you lot quite a bit of money, while keeping image quality good.  Always read lens reviews or try earlier buying, specially with 3rd party manufacturers, to brand sure you are satisfied with the photos.

Types of DSLR Lenses

At present that yous have a greater agreement most how a DSLR lens works, understanding which lens is right for you and why will be an easier chore. There are two main types of DSLR lenses:

Prime Lenses

These lenses have a fixed focal length significant that you have to motility around more when framing your shot. Even so, they are generally a much faster lens and produce a sharper paradigm. They besides tend to be lighter which is nifty for travelling.


Zoom Lenses

These lenses have a varying focal length significant that you can zoom in and out of a scene without having to motion your location. Their flexibility can be a great nugget although they tend to exist much bigger and heavier than prime lenses.

Zoom lenses work on the idea that you lot are moving various lens elements inside the lens with relation to each other, whether past turning the zoom band or pulling it forward or back.  This changes the focal length and the magnification power of the lens.


While prime lenses can aid speedily develop your photographic skills, if you are non certain what kind of photography you will be doing, a zoom lens tin be a dandy option. Within these two types of lenses there are several different more than specialised lenses available. Again, depending on the type of photography you are going to exist doing will depend on which lens you lot should choose.

Kinds of DSLR Lenses

Macro DSLR Lenses

These are the lenses that allow you to capture the tiny and intricate details of a scene. Often used in photographing minor creatures such as ants and spiders, flowers equally well as abstract images.


Macro lenses can be purposely congenital prime or zoom lenses or they can be classed as macro just because their closest focusing distance is short. The prime macro DSLR lenses will usually have a wider aperture and college quality drinking glass than their zoom counterparts, therefore producing a college quality paradigm.

A more affordable option if you are merely getting started is to choose a lens that besides has a macro function. This means that you can however do your everyday photography just if an occasion to capture a macro image comes along there is no need to change the lens. On the other manus, these types of lenses frequently accept a longer focal length which will lower the quality of the paradigm.

Wide Angle DSLR Lenses

If landscape photography is your thing so wide-angle lenses volition exist your bread and butter. These lenses can often produce the images nosotros find most visually fascinating as the lens tin can frequently misconstrue what we see with our eyes in real life.


This distortion, however, can exist linked to the quality of the lens. With the superlative wide bending DSLR lenses giving fiddling to no distortion or chromatic aberration whereas the more affordable will see more. You are able to right for this in editing software.

Broad angle DLSR lenses are available in both prime and zoom lenses with quality and affordability varying between the two. To decide which is for you, first y’all demand to remember virtually what you will exist using it for. For example, if you are shooting portraits where you lot are able to easily move yourself around to capture the shot then a prime lens possibly best. However, if you lot are  shooting a alive functioning where you are in a fixed position a zoom lens is probably going to exist a better option.

Telephoto Lenses

If you are looking to photograph subjects from far abroad, then a telephoto lens is for you. They are more often than not lenses that take a focal length of 85mm or longer and like the other lenses they come in both prime and zoom.

When information technology comes to telephoto lenses though, information technology is the zoom lenses that are the well-nigh popular. This is because the situations that yous by and large demand a telephoto lens require a piffling flake of flexibility and a zoom lens gives you that.


Zoom telephoto lenses are particularly popular with sports and wildlife photographers every bit they are able to follow a subject without having to move much themselves. These lenses as well tend to have image stabilisation features which can be really helpful. It helps cut down any shaking or vibrations which become more than obvious at longer focal lengths.

Standard DSLR Lenses

Your general purpose, all-round and kit lenses are neat when yous are just starting out. They allow you to do multiple unlike types of photography with but i or two lenses. This means you can figure out which kinds of photography you are nearly interested in earlier ownership more specialised lenses. They are also pop with event and wedding photographers where the act of changing lenses can hateful missing a potentially amazing shot.

These lenses are generally zoom lenses and because they are built to do multiple unlike things the overall image quality is not as high as a prime number lens. However, there is a huge diversity with some even having the ability to go from a broad angle to a long telephoto! Obviously the more you want the lens to do the lower the image quality will be. Withal, it is a peachy option if you are just starting out.

Portrait DSLR Lenses


If shooting portraits is your jam, so bagging yourself one of these lenses is a no brainer. These lenses are generally prime lenses and so deciding on what kind of portrait you want to capture will help yous decide which focal length to get.

In general, a great starting point is to go for a focal length of around fifty-85mm. This is because you can capture the soft beauty of a subject while still being able to add some drama and vibrancy.

Fisheye DSLR Lenses


These lenses are ultra-broad-angle lenses and produce a full 180-degree radius image. These types of images are instantly recognisable as they distort the image and make everything look similar its in a bubble. These types of lenses are usually prime lenses.

Tilt Shift DSLR Lenses

Also known as perspective-command lenses they allow you to shift and tilt the optical configuration of the lens relative to the sensor. Basically, it means that when yous are photographing buildings you can correct for key stoning (an effect that makes buildings appear like they are falling over).

You tin besides arrange the depth of field without irresolute the aperture which can exist helpful in landscape and production photography. On the other hand, they only have the power to focus manually.

Other Things to Consider


Not all lenses are perfect, and they all have varying degrees of distortion. Prime number lenses usually accept the to the lowest degree because they do not have to accommodate a range of focal lengths. There are two principal types of distortion to exist aware of when choosing your lenses: Butt distortion and Pincushion distortion.

Barrel distortion is when the edges of the paradigm look barrel-sized rather and so straight. Pincushion distortion on the other paw is the contrary. It makes the edges bow inwards. Yous can also get an image that has a mixture of both which is known as a complex distortion.

As technology improves mod zoom lenses are not plagued by distortions as much. Although it is worth noting that these distortions can often exist corrected for in photograph editing software.


One of the reasons multiple lenses or glass elements are used inside a camera lens is because while a unmarried lens could form an image, it would have aberrations.

Quondam the calorie-free that passes through your lens is not all aptitude in exactly the same way and causes what is known as aberrations or edges of the paradigm that are non coloured correctly. There are some colours that are affected past this more than others and as well some lenses. Y’all can ofttimes correct for this using editing software though.

Chromatic aberration lens diagram

Chromatic aberrations are also diminished when unlike material lenses are used together in the grouping, therefore realigning the colors.

Lens Sharpness

Lenses are usually sharpest in the heart and sharpness also isnt the aforementioned throughout a lenses zoom range.  As I said earlier, lenses have come a long manner now that nosotros use DLSRS, but they are non perfect all the same.  If you utilize your lens for many types of projects you will learn its sharpness qualities.  I thing in common is lenses are less abrupt when the aperture is wide open, so if you are experiencing that issue use a smaller aperture.

Well, that is it for my review of how DSLR lenses piece of work and differ.  I promise this commodity has helped you empathise lenses more.  Every bit y’all can run into its not all that complicated.

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