the latest EOS bodies (like 1v)utilize CMOS technology for AF? What is CMOS? does this af system perform better than others? i read from one of the entries here that metering accuracy increases with the no. of zones but i dont understand why the high-end 1v uses 21-zones whilst the lower end eos 300 uses 35-zone? thank very much

-- legnum (legnum212@email.com), June 03, 2001

Answers

CMOS is just a different type of semi-conductor. They have been traditionally regarded as inferior to CCD's, but Canon has gotten very good at using them. Their main advantage, from a manufacturers standpoint is that they are cheaper to make and you can affordably make them larger. Canon also uses one as the image sensor in the D30 digital SLR, and, by all accounts, it works very well. It's advantage as an AF sensor in the EOS 3 and 1v is that it almost completely covers a very large part of the image area. CMOS is also used in the EOS 30/Elan 7e and 300/Rebel 2000. It's down side in the latter two cameras is that it isn't quite as sensitive in dim lighting. That doesn't seem to be a problem with the 3 and 1v though.

Metering accuracy doesn't always increase with the number of metering zones. The metering accuracy of a 10 zone system might be slightly better than a 5 zone system, but the difference between 21 and 35 really isn't relevant. What plays a more important role is the programming and memory space that is used to determine what those 21 or 35 zones really mean. People that have used both the 3 and 1v extensively, report that the 1v seems to have the edge in predicting accurate exposures.

-- Jim Strutz (jimstrutz@juno.com), June 04, 2001.