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The Mirrorless Mode on DSLR Cameras

2020-06-18 4 min read Photography Tech explained Teknikal_Domain Unable to load comment count

Note: I’m a Nikon person. Say what you wish, but my experience is with Nikon. Other manufacturers may vary.

Just about every modern DSLR has a few shooting modes. Single, continuous, quiet, and so on. Well, one of those modes turns the camera into, for usability purposes, a little mirrorless, without, well.. most of the benefits of a mirrorless. What am I talking about? Well, live view, what else?

Lv as Nikon calls it, and for brevity reasons, what I shall call it from this point forward, fundamentally does two things to the camera:

  1. Raises the mirror, continuously exposing the sensor
  2. Displays the current picture onto the screen

The end result is a view of the current shot settings, well, shown live. On some this may be a mode (D300), on the D3500 I saw, a level just off the main shooting mode dial, on the D7000 that I’ve had my eye on, it’s on the same piece as the record video button.. we’ll get to that in a second. The point is, the position of this may vary, check your manual, though it’s usually not a hidden feature. In Lv mode, your camera is, for all intents and purposes at this point, a mirrorless camera.

Now in the SLR design, the viewfinder uses some optical manipulation to show you a view through the lens.

SLR design
1

  1. Lens assembly
  2. Mirror in down position (image visible in viewfinder)
  3. Focal-plane shutter
  4. Sensor/Film
  5. Focusing screen
  6. Condensing lens
  7. Pentaprism or Pentamirror
  8. Eyepiece

Really, this is what gave birth to the entire name: the camera has a single lens, not a separate one for the viewfinder, and “reflex”, as an adjective, meaning “Bent, turned, or thrown back; reflected.” is a pretty accurate description of the light and image coming in from said singular lens.

The inherent problem in this design is that you get the picture from the lens and not the sensor. using live view shows you what the sensor sees, meaning that changes to shutter speed, ISO, and other settings actually have an effect on the preview that you have.

Of course, if the camera is electronically polling the sensor (electronic shutter), then that means that it’s constantly exposed, which is why things like pointing it into the sun are specifically and strongly discouraged in Lv mode.

With Lv mode though, just about any adjustment can be shown real-time, as well as extra information that can’t really be given on the rather sparse LCD displays inside the viewfinder, like exact focus locations, and other camera operating conditions. With a true mirrorless, the viewfinder is an electronic display inside an eyepiece. With this, the best you have is the giant screen on the back.

There is one extra feature of Lv: video recording. In fact, Lv is a video recording, just instead of saving the captured frames to the storage medium, they’re being composited with the rest of the symbology and sent to the camera display. Now, DSLRs with Lv aren’t necessarily the best at this, as, well, that’s not their main point really (unless you go high-end. Then it is), a true mirrorless is usually going to beat them, video-wise, but hey, even a mid-range 2010 camera can record 1080p24, which is actually… really, not that bad. Most people if they needed a good video would just whip out their phones anyways, mine can do 4k60 or even 8k30 if I wanted to take the time to properly decode the video data it produces.

But in the end, yes, we are slowly going to end up transitioning to mirrorless cameras being the norm. But for the time being, there is a way to bridge the gap: live view. If you’re interesting in swapping your DSLR for a mirrorless, grab it, see if it has Lv, if so, try using that as your primary shooting mode where possible, see how that feels. Just… know that there will be come differences (like camera size) that you cannot just change by flicking a switch.


  1. By Wikipedia user Colin M.L. Burnett (Cburnett) - Own work with Inkscape based on Image:Slr-cross-section.png , CC BY-SA 3.0 , link . ↩︎

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