With conventional auto-focusing, auto-focus is driven by electromagnetic force of a DC-motor, gear and shaft mechanism. However, Ultrasonic Oscillation Energy operates the HSM lens and creates high-torque drive. Since this motor has no reduction gears, it has much quicker response to start and stop compared to DC- motor lenses.

A bifocal lens only allows you to have two vision distances (near and far) while progressive lenses give you all your range of vision from distance, intermediate and near in a smooth progression. Most people like the newer technology of the progressive because it allows for more natural vision and cosmetically they look nicer because there is no line. The upside to standard lined bifocals is that the peripheral vision is sometimes better.

DC or DD (Direct Drive) is same as Auto Iris lens but there is no amplifier built-in the lens. Amplifier is in the camera and camera drives the lens iris again through the cable plugged into the camera. Plug is same as in A/I lenses.

DC permanent magnet motors are readily available on surplus web sites, thrift stores, garage sales, and old cars. Here is a Leeson 14 AMP DC Motor which is very much suited to be a generator. Click here to see more information about this DC motor/ generator. The interesting thing about using these motors is that most of them create DC power that can easily be fed into an AC inverter so you can power up your television or computer with it.

Having the focusing motor in the lens allows the lens to have a motor that is "matched" to its focusing characteristics. Heavier glass can be supplied with more powerful motors. It should also simplify lens design since there is no need to design a transmission that takes mechanical energy from a fixed point in the lens mount to some other point in the lens. With the motor in the lens, the motor can be placed where ever it will be most effective. In some cases, it probably does.

HSM stands for "Hyper Sonic Motor". The HSM motor is driven by ultrasonic waves and it makes auto focusing, precise, silent and high-speed. Sigma's HSM version lenses are available only for AF Sigma, Canon and Nikon AF cameras.

If you want a long lasting and more powerful, professional quality dryer, buy an AC motor dryer. A dryer with a DC motor is usually lighter and less expensive, however it will need to be replaced more frequently. DC dryers are best suited for at home use.

With DC (Direct current), the current always flows in one direction with no relation to change in time, as is the case with a dry cell battery or a car battery. (The DC output of Honda generators is for charging batteries only.) Alternating current, on the other hand, reverses its direction at uniform time intervals. Almost all-household electrical appliances are made to run on alternating current. Well, let’s use an example to illustrate why.

Both AC and AC/DC welders have a large transformer in them that converts the power from the wall outlet to a voltage that is proper for welding. AC welders simply convert the outlet AC voltage - DC welders convert the voltage AND change the AC from the wall outlet to DC. When the electricity is changed to DC, it has a polarity associated with it. AC (alternating current) power has no specific direction - it cycles back and forth 60 times a second (alternates).

Most of the countries use alternating currents (AC). DC stands for direct currents. All appliences and voltage transformers run only on AC electricity. There is no worldwide standards for the plug configuration. Plugs, plug shapes, electric outlets differ from country to country. For that reason you need to get a plug adapter, in order to plug your aplliance into foreign electric outlet. You still need a voltage converter, otherwise you might demage your applience or cause fire!

All motor oils are made up of base oils and additives. In general, fully synthetic motor oils contain non-conventional, high-performance fluids. Semi-synthetic oils (also called "blends") usually use a small percentage of non-conventional, high-performance fluids in combination with conventional base oil.

Almost all modern cameras have a receptacle for A/I and DC lenses. It is small rectangular connector usually in the back of the camera. When selecting camera you should pay attention to select one which will accept both types of lenses.

There is a little switch-selector labeled DC-A/I (or similar) and you have to select switch to match type of lens you have.

A little of auto iris functions are built-in in most of cameras included in most observation systems today. But, when you use professional cameras you may need to separate DC drive auto iris, a motorized device to meet the changes of lighting condition of the sun. Generally, auto iris device is not necessary for indoor application with artificial lightings.

We hope to raise gifts and pledges of $4.5 million by the end of 2007 and complete construction in 2008.

DC Direct is the exclusive collectibles division of DC Comics which manufactures and markets over 100 products each year. These products, ranging from action figures to cold-cast porcelain statues, are based on the world famous DC Comics Super Heroes, the edgy stars of Veritgo and the timeless icons of MAD Magazine.

I would say no difference at all. Both kit and plans-built aircraft go by many names interchangeably. Experimental category, amateur-built, home-built, custom-built all mean pretty much the same thing. By regulation they all require the owner builder to do at least 51% of the construction work. If this basic requirement cannot be met, the aircraft may be subject to certain more restrictive FAA documentation that essentially limits the final use to display and exhibition purposes only.

The lens is the part of the eye that helps focus light on the retina. The retina is the eye's light-sensitive layer that sends visual signals to the brain. In a normal eye, light passes through the lens and gets focused on the retina. To help produce a sharp image, the lens must remain clear.

A lens implant (intraocular lens or IOL) is a man-made, clear plastic lens approximately 6 mm in diameter which is placed inside the eye at the time the cataract is removed. It replaces the natural lens and remains permanently within the eye. The lens has small spring-like arms called haptics that prevent the lens from moving out of place.