Shulou(Shulou.com)11/24 Report--

When it comes to the motor in the camera and lens, I believe that the first thing that comes to mind is the focus motor of the autofocus lens.

Some early brands chose the body drive scheme, and most brands now choose the more efficient lens built-in motor. (PENTAX has also begun to include focus motors in new lenses in recent years)

Minolta AF7000 is AF SLR (red circle is the driving gear) DC motor and its derivatives have basically withdrawn from the mainstream field of vision, the main focus motors currently used are STM stepper motor, ultrasonic motor, and XD / VXD / SSVCM as the representative of the new high-performance motor.

▲ DC motor STM stepping motor used in early low-end lens has two driving structures: gear type and lead screw type:

- Gear type slower speed, work noise. If you have a bad impression of "STM," then there is a high probability that you will encounter an STM gear type drive structure.

- The lead screw type allows the focusing lens to move linearly, making the focus smoother and faster. It is a good choice for both cost and focusing performance.

STM + lead screw (left) and STM + gear (right) Since its installation in 1987, ultrasonic motors have been a must-have feature of high-profile lenses for a long time. There are three common types of ultrasonic motors:

- The annular ultrasonic motor has considerable torque and is suitable for driving relatively heavy focusing lens groups of large light circle focusing lenses, telephoto/ultra-telephoto lenses. Its structure is relatively simple, reliability is also good, but the response speed is not as good as linear motor or stepper motor.

Circular ultrasonic motor-Micro ultrasonic motor has the characteristics of small size, light weight and low cost. (Nikon's use of micro-ultrasound on some gold-ring lenses, however, is "stingy.")

- Canon NANO USM and Sony DDSSM are linear drive ultrasonic motors. They have no transmission structure, work very quietly, and are suitable for CMOS AF and video shooting. However, the driving force is not as good as the annular ultrasonic motor, so the matching focusing lens group is also relatively lightweight.

* When the linear focus motor is not energized, the focus lens may shift, that is, if you shake the lens, you can feel the lens sliding inside, which is normal.

Canon NANO USM new high-performance motors mainly refer to Sony XD, Tamron VXD and Nikon SSVCM. These three types are high-performance focus motors born from the micro-single era, all of which are linear focus. Sony official information is more limited, the name is more abstract, while Tamron and Nikon have more specific structure, schematic diagram. I personally prefer these three technologies to be of the same kind and look forward to a deeper interpretation from a big shot.

Sony XD Motor

▲ Tenglong VXD motor

▲ Nikon SSVCM motor From the official disassembly diagram, Sony part of the lens XD motor and focusing lens group using non-metallic material bracket (Tamron situation is similar, Nikon Z 400/2.8 VR S and Z 600/4 VR S have not seen disassembly), in the event of collision may not be as reliable as the traditional ring ultrasonic motor.

▲ Sony FE 50mm F1.2 GM lens XD motor and focusing lens group Finally, the motor is not only used for lens autofocus, but also for aperture blade control, electric zoom and sensor displacement anti-shake: Canon early DC has used ultrasonic motor to drive zoom products, Sony also used ring ultrasonic, XD motor to drive lens zoom.

▲ Sony FE PZ 16-35mm F4 G XD motor for electric zoom and focus respectively

▲ Canon uses USM ultrasonic motor for zoom digital camera This article comes from Weixin Official Accounts: Camera Notes (ID: xjbiji), Author: Teng Feiet

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.