What is a Digital SLR?

To answer the question "what is a digital SLR" some tech jargon is required - but I promise to use at little as possible.

Many consumers are much more familiar with compact digital cameras and smartphones that take pictures, since they are everywhere.

Thanks to the smartphone, it's hard to walk down the street these days without seeing someone snapping a photo. Digital SLR cameras are less common, and up until 2005 were only used by professionals or photo enthusiasts with deep pockets.

The good news is that the price of digital SLRs keeps falling and many are competitive now with the high-end compact cameras. This also means that "regular" photographers are hearing about these cameras and aren't quite sure what they can do.

So what is a digital SLR? Let's find out.

SLR Defined

SLR is an abbreviation: it stands for Single Lens Reflex.

Now you know what SLR stands for but that doesn't really help answer the question, does it? Let's define further:

  • With an SLR camera, you see exactly what the lens sees
  • You can change the lens on a digital SLR
  • Digital SLRs have large image sensors that produce high-quality photos
  • An SLR has a near-zero lag time, and is ideal for action photography

Bottom line? Digital SLR cameras are versatile.

You can take photos of everything from sleeping kittens to race cars and you'll never be limited by your camera.

With an SLR in your hands you can rest assured that you'll only miss great photo opportunities because you weren't prepared, not because your camera wasn't able to get the shot.

The Anatomy of a Digital SLR

To properly answer "what is a digital SLR?" you have to understand a bit about the mechanics of an SLR camera.

In order to avoid getting overly technical I've simplified this diagram and am highlighting the key elements. Those interested in the minute details can read about Single-lens reflex cameras on Wikipedia.

  1. Light passes through the lens and strikes a mirror (green)
  2. The mirror reflects the light up to a focusing screen
  3. Light passes through the focusing screen and enters a block of glass called a pentaprism (orange)
  4. The pentaprism reflects the image so that you can see it in the viewfinder
  5. When you take a photo, the mirror flips up and a shutter (blue) opens that exposes the digital sensor (red) to light

This is a great example of what-you-see-is-what-you-get. By using the viewfinder you can precisely compose your image and adjust the focus.

Is the image that you see in the viewfinder 100% accurate? In most cases it isn't. If you read digital SLR camera reviews, you may hear a lot about viewfinder "coverage" and "brightness".

Many digital SLR viewfinders only show you 95% of the image that will be captured by the sensor - this is what "coverage" refers to. Unless you are extremely precise when it comes to your photographs you won't notice the 5% difference.

Digital SLR viewfinders also vary in brightness, which is another way of saying how clear the image appears. "Bright" viewfinders make it easier to use manual focus, since you can clearly see the details of your subject.

A Lens for Every Occasion

In addition to the pentaprism viewfinder, one of the key features of any digital SLR camera is the ability to change lenses.

Most people think that the camera alone is responsible for capturing an image, but this isn't the case.

The lens that's attached to it can play a huge role in the color, contrast and clarity of every single photo that you take.

Owners of digital SLR cameras can buy lenses that match their photography style, since a landscape photographer should not use the same lens as a wildlife photographer.

The ability to swap lenses at any time adds to the versatility of a digital SLR camera, and means that even if your photography needs change in a couple years, you won't have to buy a new camera, you'll just need a different lens.

Next Steps

Hopefully you're starting to feel more comfortable about this whole digital SLR camera thing.

If close friends pop the question "what is a digital SLR?" you'll be able to respond in an educated fashion (just throw out the term "pentaprism" and watch their eyes go wide).

Let's take it a step further.

I am a digital SLR enthusiast - this web site probably gives that away. I think that there are many advantages of digital SLR cameras.

But I also know that a digital SLR isn't the right camera for everyone. The main drawback is their size — you can't just shove a DSLR in your back pocket and be on your way.

If you've already considered this and are convinced that a digital SLR is the right camera for you then it's time to define digital SLR terms.

A clear understanding of digital SLR jargon will help you decide which camera features you must have — and which ones you can live without.

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