Digital SLR Live View LCD

Let's jump into our discussion of live view LCD screens by answering a simple yes or no question.

Question: can a digital SLR camera show a preview of the image that you're about just like every compact digital camera on the market today?

Answer: no.

While this answer is true for the vast majority of digital SLR cameras, there are a few notable exceptions that do include live view LCD screens.

Why Can't My SLR Show Me an Image Preview?

People ask me this question an awful lot, so I decided that it was high time that I posted some information about it here at the Digital SLR Guide.

In order to ansswer it, you have to understand how your digital SLR camera is constructed.

When you're not about to take a photo, the light passing through the lens strikes a mirror that sits in front of the digital SLR sensor.

This mirror reflects the light up into a pentaprism, which in turn reflects the image so that you can see it in the viewfinder.

Image Latency

The huge advantage of this optical system (vs. the electronic ones included in compact digital cameras) is that there is no image latency.

Image latency is a term that is used in conjunction with video displays when there is fast-moving action on the screen.

Since most video displays can't keep up with really fast movements, they blur (or "ghost") images.

Want to see this for yourself? Just take any compact digital camera, activate the LCD screen and then move the camera rapidly back and forth while you watch the LCD. That blurriness that you see is the image latency.

The real issue with image latency is that it makes it hard to track fast-moving subjects. Imagine trying to take photos at a sporting event or of a jackrabbit with a screen that keeps blurring the display.

Since no electronics are used to display an image in the viewfinder of a digital SLR, you can whip the camera all over the place and never lose track of your subject in the viewfinder.

Unfortunately this optical display comes with a price.

Compact Digital vs. SLR

Compact digital cameras are able to display a live preview on the LCD because when you turn the camera on, the sensor inside the camera activates.

Since there is nothing in between the lens and the sensor, the sensor picks up light and immediately transmits images to the LCD screen.

Can you guess now why a digital SLR camera can't do the same thing?

If you said "there's a mirror in the way!" then you've found the right answer.

The only time the mirror moves out of the way is when you press the camera's shutter release button to take a photo.

The rest of the time, the mirror blocks the sensor so that it can reflect light up to the pentaprism and viewfinder.

With no way to collect light, the sensor CANNOT display a preview of the image you're about to take on the LCD screen.

The Live View Breakthrough

In 2006 Olympus introduced a camera called the E-330.

While comparable to other digital SLRs in many respects, the E-330 included one stand-out feature: a live view LCD.

How did Olympus pull this off?

The answer is pretty simple when you think about it: they just added a SECOND digital sensor in the path of the light reflected by the mirror.

The second sensor captures the image that is being reflected up to the optical viewfinder and then transmits that image to the camera's LCD.

Voila! A live view LCD screen on a digital SLR camera - the first of its kind.

Panasonic was soon to follow (it's no surprise - they're partnered with Olympus) and followed on the heels of the E-330 with the DMC-L1.

What the Future Holds

I expect that this live view LCD technology will become commonplace over the next couple of years in digital SLRs.

Since it is a standard feature on compact cameras, it leaves many wondering why they should "upgrade" to an SLR camera that can't do the same thing.

It also comes as a real shock to folks who have purchased a new digital SLR camera, only to find out after the fact that they must use the viewfinder to compose all of their photos.

Time will tell, but this has the potential to be the one feature that really causes many compact camera owners to make the switch to a digital SLR.

The flexibility of a live view LCD also provides photographers with more creative ways to compose photos, something that can be leveraged by professionals and novices alike.

See all of the latest digital SLR cameras with live view LCDs