Speed of sd/cf card


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Yappy

Senior Member
May 30, 2004
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#1
The vendor will always indicate on the memory card the speed. e.g. 133X, 266X then what is 133X or 266X?

How do you determine the speed of the card both read and write?

Is the write function more critical than read function?
 

SilverPine

Senior Member
Jul 8, 2007
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Singapore
#2
The latest trend is that the vendor indicate speed of data transfer rate of the card, for example 15 MB/sec. If your camera is 3fps and each picture file size is 5 MB, then 15MB/sec is good for you. Some of high speed card indicate 25 MB/sec, and if you take picture wiith RAW file type for file size of 8 MB each , for 3fps camera it is fast enough.

Writing speed is more important for picture takeing.

Cheers
 

Yappy

Senior Member
May 30, 2004
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#3
The latest trend is that the vendor indicate speed of data transfer rate of the card, for example 15 MB/sec. If your camera is 3fps and each picture file size is 5 MB, then 15MB/sec is good for you. Some of high speed card indicate 25 MB/sec, and if you take picture wiith RAW file type for file size of 8 MB each , for 3fps camera it is fast enough.

Writing speed is more important for picture takeing.

Cheers
Hi Bro.....

Tks for the reply. Appreciate it very much!
 

Cursor

New Member
May 24, 2003
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cursor.instantlogic.com
#4
The vendor will always indicate on the memory card the speed. e.g. 133X, 266X then what is 133X or 266X?

How do you determine the speed of the card both read and write?

Is the write function more critical than read function?
Hi Yappy,
Quote from Wiki:
There are different speed grades available which are measured with the same system as CD-ROMs, in multiples of 150 kB/s (1x = 150 kB/s). Basic cards transfer data up to six times (6x) the data rate of the standard CD-ROM speed (900 kB/s vs. 150 kB/s). High-speed cards are made with higher data transfer rates like 66x (10 MB/s), and high-end cards have speeds of 200x or higher. Note that maximum read speed and maximum write speed may be different, with maximum write speed typically 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. The SD card specification 1.01 allows for a maximum speed of 66x. Higher speeds of up to 200x are defined by specification 2.0.

The following table lists some common ratings and their respective maximum transfer rates.
Rating Speed (MB/s)
6x 0.9
32x 4.8
40x 6.0
66x 10.0
100x 15.0
133x 20.0
150x 22.5
200x 30.0
SDHC
SDHC (Secure Digital High Capacity, SD 2.0) is an extension of the SD standard that appeared in June 2006. SDHC allows standard-compliant capacities in excess of 2 GB. SDHC cards are often formatted with the FAT32 file system. It uses the same form factor as SD, but the SD 2.0 standard in SDHC uses a different memory addressing method (sector addressing vs byte addressing), thus theoretically reaching a maximum capacity of up to 2 TB (2048 GB). However the SD Card association have artificially defined the maximum limit of SDHC capacity to 32 GB. SDHC cards only work in SDHC compatible devices, but standard SD cards work in both SD and SDHC devices. The SDHC trademark is licensed to ensure compatibility.

SDHC cards have SD 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":

Class 2: 2 MB/s
Class 4: 4 MB/s
Class 6: 6 MB/s
SDHC cards will often also advertise a maximum speed (such as 133x or 150x) in addition to this minimum Speed Class Rating. See section Speeds above for a further explanation. One critical difference between the Speed Class and the maximum speed ratings is 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. "Maximum speed" ratings are quoted by the manufacturers but unverified by any independent evaluation process.
 

Yappy

Senior Member
May 30, 2004
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#5
Hi Cursor..

Thanks for the sharing... yappy
 

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