Canon lenses what is usm

USM lenses are fast, but they can be very jerky. The AF motor starts, it stops, it moves back and forth like lightning. USM lenses are much faster than STM lenses, which makes USM a better choice for action photographers, street photographers , and wildlife photographers. USM lenses also offer smoother manual focusing, given the mechanical connection between the focus ring and the focusing mechanism.

This is important for photographers who frequently manual focus—such as macro and landscape shooters. To be effective, a ring-type USM motor needs to meet certain requirements. It must be powerful enough to drive the focusing lens group quickly and easily at low speed, so as to avoid the need for a gear system to reduce the speed. It must exhibit high levels of holding power, so that once the motor is switched off, the focusing lens group is held in place without any further input needed.

It should be simple to manufacture, and should start and stop quickly to ensure the best focus response. It should also be as quiet as possible in use. In addition to these features, ring-type motors are also highly efficient and have low power consumption to maximise the camera battery life. Being ring-shaped, they are ideal for fitting within the lens barrel. The ring-type USM is actually very simple in operation. It is composed of a rotor and a stator — an elastic body with a piezoelectric ceramic voltage element attached to it.

Applying an AC current with a resonant frequency around 30kHz to the stator creates vibrations that cause the rotor to rotate continuously. The frequency of 30kHz is in the ultrasonic range, and this is where the USM motors derive their name.

The piezoelectric element generates ultrasonic waves which, a bit like ocean waves propelling a surfer, cause the rotor to create a rotational force that moves the focusing group. Switching the current between two different phases changes the direction of the ultrasonic waves. Consequently, the focusing group can be made to move in different directions, giving control over the direction, speed and degree of focus adjustment. Unlike the ring USM, where the stator and rotor are separate parts, in the Micro USM design the rotor, stator and drive gear are combined into one unit roughly half the weight of a ring-type USM motor.

While the more powerful ring-type USM is designed to fit in the circular barrel of a lens, making it ideal for use in large professional zoom lenses, the Micro USM motor was created to fit in a wide range of lenses without being restricted to the size of the lens barrel.

Micro motors are also cheaper to produce, making them more suitable for use in consumer lenses where cost is an issue. There are four piezoelectric layers, each constructed from two alternating phase piezoelectric elements. Applying an AC current to only the A-phase causes the stator to vibrate left and right.

If current is applied to the B-phase, the stator will rotor forwards and backwards. When current is applied to both the A-phase and the B-phase, the resulting motion is rotational as the tip of the stator moves, for example, left, back, right, forward, left, back, right, forward.

This rotational force is applied to the main drive gear, which in turn is used to drive the gears of the focusing mechanism. It functions in a very similar way, but the length of the unit has been greatly reduced to allow it to be used in ultra-compact zoom lenses. The reduction in size has been achieved by reconfiguring the rotor and stator so that, instead of the two being aligned in a row, part of the stator is placed inside the rotor.

This required the creation of a new format of vibration, so that the resonant frequency of the piezoelectric elements was not too high, resulting in insufficient vibrational amplitude. The next focusing motor technology developed was a little different.

First introduced in , STM lenses are good for stills but they're great for video because the STM stepper motor produces smooth, quiet focusing movement. A stepper motor uses DC direct current passing through multiple coils organised into groups. Supplying current to the groups in a sequence rotates the motor one step at a time. Find light in darkness with these tips and techniques.

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Canon Focusing Technology. When we look at a photograph or movie, one of the first things that we notice is whether it is in focus or not. Since , when Canon became the first company to integrate a focusing motor inside the lens, mulitple motors have been introduced that are designed to acquire and track focus for fast moving subjects. All while retaining control for focus accuracy, smoothness and silence.

There are currently three main types of focusing motor technologies used within Canon lenses. I prefer to use USM lenses for wildlife photography due to this feature. The quick focus is an essential requirement for wildlife and bird photography. If you are planning to invest in professional grade lenses for photography, I strongly recommend going for the Canon USM lenses. The fast focusing feature of the USM lens makes it more photographer friendly.

Thus, the image quality will be better. If you are into action photography, sports photography, wildlife photography, or bird photography, then the USM lens will be the best choice. If you are using the camera to capture videos, then you will be recording the audio also. The USM lenses will make noise when trying to focus on the subject. Thus, you will end up with low quality audio for the video. So, if you are using a USM lens for video, it is better to use an external microphone kept at a distance from the camera.

It will help to avoid the motor noise pick up during autofocusing. STM lenses produce less jarring and smooth videos.