Archived posting to the Leica Users Group, 1998/01/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]<< Also, in my ignorance, I assume that the auto focus cameras have a motor and gears and powerful batteries to drive the lens in an out. Must be quite a show if you are using a big zoom lens and trying to follow some action or just scanning back and forth between near and far objects. No wonder the SLR cameras are so big and heavy. >> Don't fool yourself. The motors in the Canon EOS system are in the lenses. These are mostly USM (ultrasonic motors). They are very small and light. Many lenses, including all of the longer lenses all have internal focusing, which moves only a small lens groups or groups inside the lens. Fosusing is very fast - less than .4 seconds for many of the lenses from exterme close to extereme far positions. For long lenses, this is far faster than can be done manually. A Canon Elan IIe is lighter than an M6, though somewhat larger. The Contax G2 uses a motor in the camera body for AF, and it is no heavier than an M6. The Contax AX uses an ultrasonic motor in the body to move the film plane back an forth for AF. (AF focusing is not done with the lenses themselves, although some of the longer lenses must be rough focused for close up work). The standard battery for the Canon Elan IIe, Contax AX, Canon 1N and many other AF cameras is the 2CR5 litiium - which is the size of two AA batteries. The batteries in the G2 are even smaller. Tom Shea