Since the time of the first camera obscura, the oldest records of which are about 470 BCE, the idea of directly observing a subject was integral to the photographic process. In one way or another light has entered a camera and the photographer has looked at a direct optical representation of the subject in order to compose and capture that photo. Large format cameras used ground glass plates, rangefinders used secondary lenses adjacent to the main lens, and the single lens reflex uses a mirror to bounce light into a viewfinder.
One of the defining characteristics of a mirrorless camera though is the lack of an optical viewfinder, which is possibly more pronounced of a change to the way images are captured than was the advent of digital sensors. For the first time in the evolution of photography the photograph isn’t directly looking at the subject, but instead is looking at a high-quality video feed of the subject. That means that light enters the camera, strikes the sensor and then the sensor produces an image from the resulting signal.
There are some profound differences between seeing your subject optically and electronically, and until recent cameras like the a7 series, the drawbacks of this technology by far outweighed the advantages provided. But with super-sharp Electronic Viewfinders, also called EVF, this has changed and for the first time cameras without optical viewfinders are able to provide more benefits to the photographer than those with light passing directly though a viewfinder.
The EVF in the Sony a7 
is by far one of the best in the class—it had to be in order to get professional photographers to abandon the optical viewfinders of their pro bodies. The EVF on the a7 has 2.4 million pixels and 100 percent coverage. That means that everything seen in the viewfinder will appear in the final frame. With some EVF systems (and some OVF systems as well), especially on consumer systems, there is less than 100 percent coverage, meaning that some part of the captured image will be outside the borders of what’s seen inside the viewfinder—that’s less than desirable when composing an image.
Earlier EVF systems, especially those found on consumer cameras, were dreadful. Many were lower than 100 percent coverage, and their resolution was too low to be a true focusing aid. Many photographers swore off EVFs (and swore at them too) because of the early consumer models. Luckily the technology has evolved radically and the quality of the image in the viewfinder in the a7 series is incredibly sharp and stunning.
Unlike many pro optical systems though, the a7 EVF has a .71 magnification, which means that the image that appears inside the EVF is smaller than if that same image were viewed with the naked eye. In other words, if you look at a subject through the EVF it will appear to be 25 percent smaller than it is in the real world. That’s not a huge issue, it just means that there will be less apparent detail in the EVF because the subject will appear smaller. My guess is that future generations of Sony cameras will make strides to increase this with larger EVF housings.
Before jumping into a system with an EVF, it’s important to know what you’re going to gain and what you’re going to lose.
A quick note, many of these features are true of the LCD on mirrorless systems as well. The brilliant thing here with the EVF is that you don’t have to switch into a “LiveView” mode to enable these features, as you might with a DSLR. The primary viewing tool is always available, always functional, and always powerful.
Real Time Setting Visibility
Perhaps the best thing about using an Electronic Viewfinder is that it’s possible to see the effect of camera settings in real time. Traditionally photographers needed to capture an image and then review that image to see the effect of changes to settings.
For film photographers that meant getting back developed images and for digital photographers it meant looking at the LCD screen after an image was captured, a process that’s often called “chimping” and that slows down the creative flow of a shoot.
With an EVF, changes to aperture, ISO, white balance, exposure compensation and other settings are instantly visible. The result is a tighter connection between the photographer and the camera because you can see how the changes in the settings will effect the tone and composition of your images.
This is especially powerful for beginning photographers as they often grasp with the connections between shutter speed, aperture and ISO. With the direct feedback of an EVF, even a novice photographer can instantaneously see how different settings change the look of an image.
Instant Playback
The EVF not only displays current images but can also play back any captured images. Because auto-reviewing images (seeing them as soon as they’re captured) slows down the capture process by forcing the camera to switch from live view to playback, I recommend turing this feature off but there are some times when this is incredibly handy.
When shooting with strobes, especially studio strobes, it’s particularly handy to be able to review an image as soon as it’s captured in order to check the lighting situation. Being able to see an image through the viewfinder prevents pauses between shots to confirm the lighting is correct, and enables much more fluid shoots.
On Screen Displays
Thanks to the flexibility of the LCD technology, just about any shooting data visible can be superimposed over the image. It’s possible to check histograms in real time, to see composition guides, to display a real-time level.
One of my favorite settings for new photographers is the “Graphic Display” setting that superimposes aperture and shutter speed settings over the image and dynamically changes the values as the scene changes. For a photographer that’s looking to better grasp how aperture affects shutter speed, and vise-versa, this is the perfect thing to activate.
It’s also something that’s impossible with an optical viewfinder. While current technology allows for the display of 1970’s-era LED boxes overlaid on the optical finder via the mirror, they can’t display colors, detailed graphics or moving shapes.
The EVF allows photographers of any skill level to improve their photography technique through additional on-screein information.
Focus Tracking
An electronic viewfinder can also show, in real time, what subject—and what part of a subject—are in focus, during capture. With most optical viewfinder system a camera can only display where the starting focus point is. Lock onto a moving subject and it’s possible to see where the camera locks, but then you have to hope that the system continues to track as the subject continues to move.
With an EVF the focus points lock onto a subject and then (if you’re in continuous tracking mode) continue to follow the subject, with the EVF updating the moving focus tracking in real time. This is a huge advantage, as you can see (and recompose) instantly if the focus has jumped off your subject and locked onto something else. With a DSLR you need to check the images after capturing them to see if the focus points were correct.
Manual Perfection
A lot of photographers use their Sony (and other mirrorless) systems simply to shoot manual focus lenses. That’s because a mirrorless system and a manual focus lens provide the best of both worlds. Since the EVF is always active (except when the shutter triggers) it’s capable of displaying focus information for manual focus lenses on top of the image in the EVF.
Most mirrorless systems allow photographers to superimpose focus peaking highlights, color edging that shows where the critical focus is in an image. This allows a photographer to focus a manual focus lens more quickly and more easily than on a traditional manual focus SLR. Because the camera can evaluate the focus (even if it can’t focus the lens) it can help the photographer determine if the lens is in focus or not in a way that mirrored systems just can’t do.
Video Viewfinder
Another powerful feature of the EVF on mirrorless systems is that it stays active while shooting video. That means that it’s possible to hold the camera to your eye, just as you would a full-featured videocamera, and capture video.
video
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viewfinder magnificatoin
hard to see in low light
contrast different than real life
battery life
…My daily shooter is Sony A1 with a vertical grip and various Sony lenses attached like the FE 20mm F1.8. Find more gear recommendations in our shop. As an Amazon Associate I earn from qualifying purchases.