Description:Term: Mirror lock-up
Description: Mirror lock-up reduces the vibration-induced motion blur in Single Lens Reflex (SLR) cameras
In our article discussing the “Importance of Using a High Quality Tripod When Shooting HDR Photography,” we discussed potential movement issues that can arise when shooting bracketed sequences and how using a high-quality tripod can help eliminate most of these movement issues. In this article, we will discuss how using the Mirror Lock-Up feature on your DSLR will yield even sharper images by eliminating the subtle movement in your camera caused by the mirror action. In this article, we will also explain the mechanics of the mirror in DSLRs.
THE MECHANICS OF THE MIRROR
There is a mirror inside of every DSLR (well, with the exception of new "mirrorless" cameras). When we look through the View Finder on our camera, we are actually seeing the reflection of what the mirror is seeing through the lens attached to the camera. When we press the shutter button on the camera, the mirror flips up. When the mirror flips up, the actual shutter is underneath and will open to expose the image to what the lens sees. The process of the mirror flipping up and down creates a little bit of vibration inside the camera. This vibration does not really matter when we are shooting handheld bracketed sequences because it does not make a difference in comparison to the motion shake caused by your hands, which is much greater. However, when you are shooting with your camera on a tripod, the movement of the mirror will slightly reduce the sharpness of the image. Because of this, we want to use the Mirror Lock-Up feature on our cameras whenever we are shooting on a tripod.
USING THE MIRROR LOCK-UP FEATURE
We recommend that you only enable the Mirror Lock-Up feature when you are using a tripod. When you have your camera on a tripod, enable the Mirror Lock-Up feature to lock the mirror in the “up” position so that the only thing moving inside of the camera is the shutter. This means that there will not be any vibration since the mirror will not flip up/down while the shutter opens to expose the sensor underneath.
The Mirror Lock-Up feature is great when you are shooting landscape images because this feature ensures that there is not any additional vibration introduced by the mirror as it flips up and down. The Mirror Lock-Up feature is also handy in bracketed sequences as well. Simply set your camera on the tripod and enable both the Mirror Lock-Up feature and the Auto Exposure Bracketing (AEB) feature. Your camera will then consecutively take the shots specified in your AEB with the mirror flipped up, prior to exposing the sensor with each shot.
ENABLING THE MIRROR LOCK-UP FEATURE
Each camera will be different, so consult your camera’s manual or go online to know how to enable the Mirror Lock-Up Feature.
On a Canon 5D Mark III, use the dial to scroll down to “Mirror lockup” and push the “Set” button on your camera to select “Mirror lockup.” As you can see below, the Mirror Lock-Up feature is turned off right now.
After you have selected “Mirror lockup,” spin the dial down to “Enable” and push the “Set” button again.
As you can see below, the Mirror Lock-Up feature is now enabled.
Each camera functions differently when simultaneously using the AEB and Mirror Lock-Up features. For example, if the AEB and Mirror Lock-Up features are both enabled on a Canon 5D Mark III but the HDR mode is turned off, you will need to manually depress the shutter button with each image in the bracketed sequence. This eliminates the reason to even use the feature since we would be introducing motion by touching the camera with each shot in our bracketed sequence.
However, with the HDR mode turned on in the Canon 5D Mark III and the Mirror Lock-Up feature enabled, you will be able to take consecutive shots with just one press of the shutter. If you find that you need to manually press the shutter button multiple times to shoot your bracketed sequence, then use a shutter release. Either way, using the Mirror Lock-Up feature in your camera will yield slightly sharper results when you have your camera on a tripod.
Bonus Video: What Is Mirror Lockup and Electronic First Curtain Shutter?
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