Rodzaje silników USM

[muflon]

Hmm... spojrzałem w wyszukiwarkę, wyszło mi, że przez prawie trzy lata na forum założyłem może ze 40 "normalnych" wątków ;-)

Taka kwestia: na innym forum ktoś mnie przekonuje, że są trzy rodzaje silnika USM Canona:

USMy są trzy: Micro USM (tańsza wersja, o której wspomniałeś, zresztą są dwie generacje tego silnika), zwykły USM stosowany w około 90% obiektywów oraz pełny pierścieniowy Ring-USM (równie cichy co standardowy USM, ale szybszy), zastosowany obecnie, o ile się nie mylę, jedynie w czterech obiektywach Canona.

a ja dałbym głowę, że są dwie: micro (50/1.4, japońska wersja kita, kilka starych zoomów) i normalny, który oczywiście jest dodatkowo szybszy lub wolniejszy, wprost proporcjonalnie do ilości $$$ jakie trzeba zapłacić za obiektyw ;-) ale nie ma to nic wspólnego z samą konstrukcją silnika. Jednak nie potrafię w googlach znaleźć potwierdzenia ani w jedną ani w drugą stronę. Czy znajdzie się jakiś jeszcze większy onanista ode mnie, który mi to wyjaśni, z podaniem źródeł? ;-)

[Tomasz1972]

http://www.canon.ca/digitalphotograp...p?id=182&tid=6

[muflon]

Mało Według tego to np. 100-400/5.6 czy 70-200/4 się nie łapie ("large aperture and super telephoto designs"). Ja wiem że tak jest ale potrzebuję czegoś mocniejszego.

[Tomasz1972]

żródło

Ultrasonic motor drive
Ultrasonic motor (USM) lenses first appeared with the introduction of the EF 300 mm f/2.8L USM lens in 1987. Canon is the first camera maker to successfully commercialise the USM technology. EF lenses equipped with USM drives have fast, silent and precise autofocus operations, and consume less power compared to other AF drive motors.

There are two types of USMs, the ring-type USM and the micro USM. Ring-type USM is always preferred because of its superior performance and efficiency, and it allows for full-time manual focus operations without switching out of AF mode. Micro USM is used in cheaper lenses to bring down the overall cost of the lens. It is possible to implement full-time manual focus even with micro USM; however, this is a somewhat inelegant solution, as it requires additional mechanical components, and so has not been widely implemented.

Some USM lenses are identified with a gold or silver ring and/or the label "Ultrasonic" on the lens barrel, and some of the "L" Luxury lens line-up from Canon identify each lens as using Ultrasonic with a red emblem to match the signature red stripe.

!!! Łączenie podwójnego wpisu !!!
http://photo.net/equipment/canon/lens-motors

[KMV10]

Nie wiem co to warte ale spójrz tutaj:
http://chall.ifj.edu.pl/~sapinski/pst/silniczki.shtml

[DoMiNiQuE]

ZTCW ta sa wlasnie dwie wersje: Ring-USM - czyli zwykly USM oraz Micro-USM. Nie wiem skad info o trzech wersjach.

[miszaqq]

Jednak nie potrafię w googlach znaleźć potwierdzenia ani w jedną ani w drugą stronę. Czy znajdzie się jakiś jeszcze większy onanista ode mnie, który mi to wyjaśni, z podaniem źródeł? ;-)

mowisz i masz:

What is the difference between the various kinds of lens motors (AFD, MM, USM)?

Unlike most camera makers Canon chose to position the autofocus motor inside the lens barrel rather than in the camera body when they designed the EOS system. This was arguably a wise move, since it means autofocus motor can be tailored to the requirements of each lens. A big telephoto lens can have a large motor and a small normal lens can have a more compact motor. By contrast, systems which rely on the autofocus motor being only in the camera body don’t have this flexibility - the motor is always the same regardless of the lens used unless you change camera bodies.

So. Canon employ a number of different motor technologies in their lenses. The first two types are never identified specifically on the exterior of the lens. You have to look up in Canon’s product literature to see which type of motor a given lens uses.

Traditional electromagnetic motor drives.
Such motors contain tiny wound coils of wire and rely on electromagnetic principles to turn a shaft. Little cogwheels and gears are then used to translate this rotational motion into the movement needed to adjust lens focus.

Arc-form drive (AFD).
Generally used in a number of older lower-cost lenses, AFD motors are simply little electric motors which drive a geartrain. They’re somewhat noisy - electric buzzing and grinding of gears - and not terribly fast. This isn’t a big deal on smaller lenses since the distances the motors must move the focussing elements aren’t very far. However, telephoto lenses with AFD motors can be quite sluggish.

Micromotor (MM) drive.
Generally used on a few older lower-cost lenses. Similar to AFD - slow and noisy and based around an electric motor driving a geartrain. Some particularly low-cost lenses use micromotor drives with rubber belts.

Ultrasonic motors.
Ultrasonic motors do not rely on magnetic coils like most electric motors. Instead they use extremely high-frequency vibrations which translate into circular motion. The result is a very fast and pretty well silent (to human ears, anyway) lens motor. There are two basic types employed by Canon.

Ring ultrasonic (USM) drive.
The kind you want. These motors consist of two metal rings which vibrate at a very high frequency. (have a look here for photos of these rings) Ring ultrasonic lenses are great because they focus quickly and silently and also support full-time manual (FTM). There are actually two variants of this design - see the FTM section below.

Micromotor ultrasonic (USM) drive.
This kind is less desirable. It’s a form of USM motor that Canon designed for their cheapie lenses so they can bill them as ultrasonic for marketing purposes. An MM lens replaces the standard magnetic motor with an ultrasonic motor but retains the usual geartrain setup. Such lenses are still reasonably quiet, though not as quiet as ring ultrasonic motors, but usually lack FTM - see below.

Note that, while all lenses with “USM” in the name contain an ultrasonic motor, Canon do not distinguish between ring and micromotor USM drives in the name - you have to look up the specs for the individual lens to find that out. Also, most non-L lenses with USM drives have striped gold lines painted around the end of the barrel. However, all L lenses have red lines painted around the end, whether or not they use USM (ie: Canon never have two painted rings around their lens barrels, and the red L line takes priority over the gold USM line).

ŹRÓDŁO: Canon EOS Beginners’ FAQ

Sa tam i inne ciekawe pytania (wraz z odpowiedziami na nie).

[KMV10]

Czyli wychodzi na to, że są 2 USM-y

[slawi_3000]

Pełna informacja o napędzie AF konkretnych obiektywów w tabeli do pobrania:
http://www.usa.canon.com/html/eflens...eup/index.html

[Allensteiner]

Hmm, w takim razie to: http://www.canon.com/camera-museum/t...m/f_index.html
chyba też nie pomoże, chociaż przynajmniej potwierdza wszystko co napisane w pierwszym linku. Co 2 linki to nie 1

Sam mam kita z micro-USM i 17-40 z ring-USM. Różnicę widzę tylko w braku FTM-a. Pierwszy raz słyszę o jakimś trzecim nieokreślonym rodzaju USM. Hmm

No nic, może coś pomogłem ...

Ufff ale szybki odzew i jak liczny