Archived posting to the Leica Users Group, 2009/11/05
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The card speed, according to Wikipedia.... Note that maximum read speed and maximum write speed may be different. Maximum write speed typically is lower than maximum read speed. Some digital cameras require high-speed cards (write speed) to record video smoothly or capture multiple still photographs in rapid succession. This requires a certain sustained speed, or the video stops recording. For recording, a high maximum speed with a low sustained speed is no better than a low speed card. The 2.0 specification defines speeds up to 200x. Some manufacturers use the read speed in their X-ratings, while others (Kingston, for example) use write speed.[7] Further.... SD Cards and SDHC Cards have Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum write speeds based on "the best fragmented state where no memory unit is occupied Further still.... SD and SDHC cards will often also advertise a maximum speed (such as 133x or 150x) in addition to this minimum Speed Class Rating. Important differences between the Speed Class and the traditional "X" speed ratings are; 1) the ability of the host device to query the SD card for the speed class and determine the best location to store data that meets the performance required, 2) class speed defines the minimum transfer speed. Even though the class ratings are defined by a governing body, like "X" speed ratings, class speed ratings are quoted by the manufacturers but unverified by any independent evaluation process. Summary..... faster speed rated cards may be faster. Then again, caveat emptor...... Frank Filippone red735i at earthlink.net