We all strive for pin-sharp images. The effects of camera shake can spoil your pictures, even if you have the camera mounted securely on a tripod. We explore how mirror lockup can help to keep your images pin-sharp when it matters.
Applicable models: all EOS DSLR cameras except for 1000D, 1100D, 1200D, 1300D. Not applicable to EOS M-series (these camera models are mirrorless).
What is mirror lockup?
Mirror lockup is a camera feature found on most EOS cameras. Its function is to reduce the amount of vibration produced inside the camera when you take an image.
Why is this important?
When you press the shutter button to take a photo the mirror in your camera flips up. This mirror returns to its normal position once the shutter has closed. There is a delay between the time that you press the shutter button and the instant the photo is taken. This is called shutter lag, and it is measured in milliseconds.
In order to keep the shutter lag to a minimum, the reflex mirror has to move out of the way very quickly. When it comes to a sudden halt it sets off vibrations throughout the camera body and lens. This can result in a very slightly blurred image.
If you are using a fast shutter speed, the shutter speed you have set is likely to be so short that any vibrations will not have any effect on the image. But if you are using a shutter speed slow enough to warrant the use of a tripod, it’s possible that the vibrations will introduce camera shake into the photo. The extent of the effect depends on the equipment you’re using. Heavier cameras are less likely to be affected by the vibrations, while telephoto and macro lenses will show the effects more as they magnify both the subject and the camera shake.
There are two camera features specifically designed to help reduce the effect of mirror vibration:
First, a foam strip is built into the mirror chamber to dampen the impact of the mirror lifting up. You can see the foam quite clearly if you remove the lens from the your camera.
The second is the mirror lockup function. When mirror lockup is enabled you push the shutter button once to raise the mirror, wait a few seconds for the vibrations to die away, then press it again to take a photo.
How do I set this feature?
When it was first introduced, mirror lockup was available in the Custom Function menu. More recently, it's been moved to the Shoot menus on enthusiast and advanced level cameras.
To enable mirror lockup, press the camera manu button, find the appropriate Custom Function option or correct Shoot menu. Select Enable.
When mirror lockup is enabled, press the shutter button once to raise the mirror. Pause a moment or two and then press the shutter button again to fire the shutter. The camera focuses and takes an exposure reading before it raises the mirror, which means that this technique is best suited to static subjects. It also helps if the light is steady so that the exposure doesn’t change during the pause.
It is a good idea to use a remote release so that you do not move the camera as the shutter button is pressed.
Vulnerable shutter speeds
The shutter speeds at which your images are most likely to suffer are between 1/100 and 1/4 second.
Shutter speeds faster than 1/100 second are too short to be affected by the vibrations. With exposure times of 1/4 second and more, the vibrations – which fade away quite quickly – only affect the first part of the exposure – not enough to reduce the overall sharpness. As a general rule, mirror vibrations affect short shutter speeds more than long ones.
When else is mirror lockup needed?
Close-up photography is an area where mirror lockup is useful. Any camera movement is magnified along with the image, so eliminating the mirror vibrations is an effective strategy for sharper images. You still need a sturdy tripod.
If your camera is connected to a telescope, microscope or a high-magnification macro or micro lens it can be worth applying the mirror lockup to avoid any possible vibration.
With most other types of photography this feature is not necessary as any vibration caused by movement of the mirror will be minimal compared to movement caused by hand-holding the camera.
Can I use mirror lockup when hand-holding?
In theory mirror lockup can be used while you are hand-holding your EOS camera. The best way is to set the 2 second self-timer delay so that you only have to press the shutter button once. In practice though, we doubt that anyone can hold a camera steady enough to see the benefit of the mirror lockup.
Further reading: How your EOS camera works
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Do I need a remote?
Whilst it's easiest to work with a remote – safe in the knowledge that you're not making contact with the camera – you can instead use mirror lockup with your camera's self-timer. This means that you only have to press the shutter button once to take a photo.
With the self-timer enabled, one press of the shutter button lifts up the mirror, and the camera takes a photo when the countdown is finished, then lowers the mirror.
On some cameras the self-timer delay is automatically set to 2 seconds. On other cameras you can set the delay to either 2 seconds or 10 seconds. In our tests we found 2 seconds was sufficient time for the vibrations to subside, but if you have the option you can only benefit by setting the 10 second delay.
The self-timer delay means that you can work without a remote release – any camera movement created by pressing the shutter button will have disappeared by the time the shutter fires.
Remotes and tripods to suit all budgets,
in order to keep your camera steady
and images pin sharp
About this article
This article excerpt has been taken from the April-June 2011 issue of EOS magazine. You can get a copy of this issue via EOS shop.