What is a DSLR Camera? (Explained for Beginners)

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Written By Nate Torres

Once you begin your photography journey, you’ll come across a crucial decision – picking your first camera.

But where do you begin? There’s so many options!

In this guide, I’ll be breaking down one of those camera options and defining what a DSLR camera is.

In fact, I currently still use a DSLR camera during all my professional photoshoots (I use the Canon 6D Mark II).

Me and My Canon 6D Mark II
Me and My Canon 6D Mark II

I have grown to love DSLRs, but as I’ll touch on later, they might not be as popular as they once were.

Let’s explore what these cameras are, how they work, advantages and disadvantages, and why they aren’t as popular as they used to be.

If you prefer video, then be sure to watch the video version of this guide:

What is a DSLR Camera and How Does it Work?

What is a DSLR Camera?

DSLR stands for Digital Single-Lens Reflex, and is a type of digital camera that stands apart from other digital cameras due to its mirrored reflex design scheme.

That was a mouthful, so let’s look at each individual term to get a better understanding.


The first term is “digital.”

This means DSLR cameras do not use film, and instead use digital sensors to capture images.

Camera digital sensor
Camera digital sensor

Before DSLRs, we had film cameras which we termed SLR cameras which stands for “single-lens reflex.”

SLR Camera
SLR Camera

So you add on the letter “D” for digital, and they started calling these new cameras with digital sensors, DSLR cameras.

DSLR vs. SLR Camera
DSLR vs. SLR Camera


The second term is “single-lens

This means a camera that uses only one lens.

This one lens is used for taking and previewing the image.

Back in the day, around the 1930s to the 1960s, cameras were using a twin-lens.

Twin-Lens Camera
Twin-Lens Camera

One lens was used for taking the photograph, while the other was used for the viewfinder system that allowed photographers to see their scene before taking a picture.

Single vs. Twin Lens
Single vs. Twin Lens


The third and final term is “reflex.”

This is what DSLR cameras are known for, their reflex design scheme.

The design includes a mirror that reflects the light that comes through the lens and up into an optical viewfinder.

DSLR Reflex Design Scheme
DSLR Reflex Design Scheme

This allows us photographers to see exactly what the lens sees in real time.

Can See Through the Viewfinder
Can See Through the Viewfinder

So we know that a DSLR camera is a type of digital camera that is known for its reflex design scheme.

But how does it actually work?

How Does a DSLR Camera Works?

To understand how a DSLR camera works, I’ve found it’s easier to focus on three elements within the camera:

  1. The light entering the lens
  2. The mirror
  3. The digital sensor

Looking Through the DSLR Camera

When you look through the viewfinder of a DSLR camera, you can see what the lens sees.

This happens because light enters through the lens of your camera, hits a mirror angled at 45 degrees, and then directs light up toward your viewfinder.

When Mirror is Down in DSLR Camera
When Mirror is Down in DSLR Camera

Moment of Shooting

When you press the shutter button on your DSLR, the mirror then flips out of the way, allowing the light to hit your digital sensor, capturing the image.

When Mirror is Up in DSLR Camera
When Mirror is Up in DSLR Camera

Fun fact:

The mirror flipping up is also the reason why there is a brief blackout in your viewfinder when you are taking an image and the reason there is that “click” sound.

Types of DSLR Image Sensors

DSLR cameras have different types of image sensor sizes, and the two most common are full frame and APS-C (crop sensor).

Full Frame Sensor vs. APS-C (Crop Sensor)
Full Frame Sensor vs. APS-C (Crop Sensor)

Full Frame Cameras

DSLRs with a frame the same size as 35mm film are called full frame cameras because they have full-frame sensors.

Full Frame Sensor DSLR Camera
Full Frame Sensor DSLR Camera

If you have a 50mm lens and you use it on a full frame DSLR camera, then that 50mm lens will perform true to its focal length.

For example:

Here’s a photo I took using a 50mm lens on a full frame sensor DSLR camera.

The focal length stayed true to 50mm, and then compare this with the same photo taken on the crop sensor in the next section.

50mm Lens Photo on Full Frame Sensor
50mm Lens Photo on Full Frame Sensor

Here is what full frame cameras are known for:

  • Full frame cameras are often more expensive and also heavier than their counterparts
  • They often perform better in low-light conditions
  • They have a wider dynamic range
  • They provide a shallower depth of field at equivalent apertures
Full Frame Benefits
Full Frame Benefits

APS-C (Crop Sensor) Cameras

DSLRs with an APS-C (Advanced Photo System Type-C) sensor are also known as crop sensor cameras.

You guessed it.

This is because they use a smaller image sensor compared to the full frame sensor, hence the name “crop sensor.”

Crop Sensor DSLR Camera
Crop Sensor DSLR Camera

The size difference is typically 1.4-1.6 times smaller than a full frame sensor.

Crop Sensor is Smaller
Crop Sensor is Smaller

If you have a 50mm lens and you use it on a crop sensor DSLR camera, then there will be a 1.5x to 1.6x crop factor and the focal length of that lens will behave like a 75mm-80mm (50mm x 1.5/1.6) lens.

For example:

Here’s that same scene earlier that I took with the 50mm lens on a crop sensor camera, making it behave like a 75mm-80mm focal length (more zoomed in):

50mm Lens Photo on Crop Sensor
50mm Lens Photo on Crop Sensor
50mm on Full Frame Sensor vs. Crop Sensor
50mm on Full Frame Sensor vs. Crop Sensor

Here is what crop sensor cameras are known for:

  • Less expensive than their full frame counterparts
  • More compact and lightweight
  • Ability to gather light is not as strong as full frame cameras
  • Narrower field of view due to smaller sensor
Full Frame vs. Crop Sensor Comparisons
Full Frame vs. Crop Sensor Comparisons

Camera Alternatives to DSLR Cameras

We’ve talked a lot about DSLR cameras and they are solid “professional” cameras, but what are the other options if you don’t want to use a DSLR camera?

In the beginning of this guide, I hinted at the fact that DSLR cameras are also not as popular as they used to be.

So why is that?

Well let’s look at some camera alternatives to DSLR cameras:

Mirrorless Cameras vs. DSLR Cameras

The introduction of mirrorless cameras is the main reason why DSLR cameras are not as popular as they used to be.

You see:

There is great debate among photographers that mirrorless cameras are essentially better versions of DSLR cameras and that they should be the industry standard cameras.

Mirrorless cameras operate without a mirror, hence the name.

So instead of light entering the lens and then reflecting on the mirror into the optical viewfinder, mirrorless cameras use an electronic viewfinder (EVF).

Mirrorless Camera
Mirrorless Camera

When light hits the electronic viewfinder (EVF), a digital projection of the image is shown, and you can then see changes in exposure in real-time before taking your photo!

This means if you make any changes to your exposureaperture, shutter speed, ISO – then it will be visible in your viewfinder.

Pretty neat huh?

But with any advantages, there are also disadvantages. Let’s look at them now:

DSLR Advantages vs. Mirrorless Cameras

  • Battery Life: DSLRs have better battery life because they take less power and are also smaller cameras in general so they take batteries with lower charge capacities.
  • Cost: DSLRs range in prices from entry-level DSLRs to high-end DSLRs, meaning that you can buy cheaper DSLRs. Mirrorless cameras are still relatively new so there aren’t many cost-friendly entry-level mirrorless cameras…yet.
  • Choice of Selection: You have a great choice of selection with DSLR cameras because they have been around longer.
  • Resources: You have more education resources and reviews on DSLR cameras because they have been around longer.

DSLR Disadvantages vs. Mirrorless Cameras

  • Size: Mirrorless cameras are often lighter because they do not need to include the mirror and mirror-movement mechanism within the camera.
  • Speed: Mirrorless cameras are often faster due to the mirrorless aspect.
  • Autofocus: The autofocus is generally faster on mirrorless cameras since there is no mirror obstructing the sensor.
  • Sound: Mirrorless cameras don’t have that “click” sound because of the mirrorless aspect.
DSLR Camera vs Mirrorless Camera Comparisons
DSLR Camera vs Mirrorless Camera Comparisons

Point-and-Shoot Cameras vs. DSLR Cameras

Point-and-shoot cameras are another camera alternative to DSLR cameras.

These types of cameras are often very compact, small, and easy to use, but have a fixed lens and automatic settings for focus and exposure.

DSLR Advantages vs. Point-and-Shoot Cameras

  • Manual Controls: Point-and-shoot cameras have limited manual controls
  • Bigger Sensors: Point-and-shoot cameras have smaller sensors, which can affect image-quality and low-light performance

DSLR Disadvantages vs. Point-and-Shoot Cameras

  • Portable: Point-and-shoot cameras are more portable than DSLRs, with many being able to fit in your pocket.
  • Ease of use: Point-and-shoot cameras are very easy to use, hence the “point-and-shoot” aspect.
  • Affordable: Point-and-shoot cameras are more affordable than most DSLR cameras and meant for more “casual” photographers who don’t prefer to change lenses.
DSLR Camera vs Point-and-Shoot Camera Comparisons
DSLR Camera vs Point-and-Shoot Camera Comparisons

Smartphone Cameras vs. DSLR Cameras

With the rise of smartphone capabilities, these devices that we carry 24/7 are now coming equipped with advanced cameras and computational photography features that can rival many traditional cameras.

But how do they fare against DSLR cameras?

DSLR Advantages vs. Smartphone Cameras

  • More Control: DSLR cameras have more control over settings than smartphone cameras. While smartphones are adding more and more features, DSLRs still offer more manual settings since that is their main purpose, to capture images.
  • Bigger Sensor: DSLR cameras have bigger sensors which provide stronger image-quality and low-light capabilities, however, it’s important to note that this gap is narrowing.
  • Optical Zoom: DSLR cameras have better optical zoom capabilities due to various lens choices.

DSLR Disadvantages vs. Smartphone Cameras

  • Portable: Smartphone cameras are always with you, making them very portable.
  • Casual Photography: Smartphones are starting to fill that gap and becoming the preferred choice for casual photographers who just want to take photos of their family, scenes they see on vacation, or for social media.
  • Advancing Rapidly: Smartphones are advancing at a rapid pace and keep adding new innovative features like portrait mode, night mode, and instant sharing capabilities.
DSLR Camera vs Smartphone Camera Comparisons
DSLR Camera vs Smartphone Camera Comparisons

Popular DSLR Models and Brands

After reading this guide, you may be persuaded to go with a DSLR camera.

So what are the popular models and brands of DSLR cameras?

Canon DSLR Cameras

I am a Canon user.

I began my journey with their entry-level Rebel series and I currently use a Canon 6D Mark II, which is known for being an amateur/professional-level camera.

Here are some of the leading DSLR cameras, for the leading camera brand, Canon:

Nikon DSLR Cameras

Nikon is another powerhouse within the photography industry.

Here are some of the leading DSLR cameras for Nikon:

Pentax DSLR Cameras

While not as popular as Canon or Nikon, Pentax still has a loyal following due to their durable cameras and in-body image stabilization.

Here are some of the leading DSLR cameras for Pentax:


In summary, DSLR cameras are a tried and tested type of digital camera.

While the rise of mirrorless cameras are raising questions about their “king” status of being the industry standard, and smartphone cameras are bridging the gap between casual and amateur photographers, DSLRs are still a very popular choice.

Especially entry-level models.

However, if my friends were just starting out in photography and they asked me what type of camera to get, I’d recommend they get an entry level DSLR camera like the Canon Rebel T7, and then if they wanted to upgrade, I’d probably tell them to look at the mirrorless camera options.


What Does DSLR Mean for a Camera?

DSLR stands for “Digital Single-Lens Reflex.”

What is the Difference Between a DSLR and a Normal Camera?

A DSLR is a type of camera that is known for its use of a reflex mirror that allows photographers to view through the lens, has interchangeable lenses, and has typically larger sensors.

What are DSLR Cameras Good For?

DSLR cameras are great when you need high-quality images, control over your settings, and performance in different lighting scenarios.

Is There a Difference Between a DSLR and a Digital Camera?

All DSLRs are digital cameras, but not all digital cameras are DSLRs.

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