In a few short years since the launch of the first 4Mb flash memory card, the number of flash memory cards, aka SD Cards, available for digital cameras and other devices has exploded with a number of different formats and speeds of memory card. It’s no wonder the average person is totally baffled by this plethora of memory cards.
Not only are there different shapes (the format) and sizes of memory sticks such as Secure Digital (SD) Compact Flash, Memory Stick, etc, but also different speed ratings.
Memory card speed is the card’s performance with regard to how quickly data can be transferred to or from it. The card speed is often stated in ‘Times’ ratings i.e. 12X, 40X etc (just as the speed of recordable CD’s and DVD’s is measured), and sometimes more specifically in megabytes per second (Mb/s). By today’s measure, sub 30X represents a standard speed, 30X to 60X is mid-high speed and over 66X is high speed. The chart below shows the relationship between the two figures.
8X = 1.2 Mb/sec
12X = 1.8 Mb/sec (Also known as Class 2 for SD Cards)
20X = 3.0 Mb/sec
25X = 3.8 Mb/sec (Also known as Class 4 for SD Cards)
30X = 4.5 Mb/sec
40X = 6.0 Mb/sec (Also known as Class 6 for SD Cards)
60X = 9.0 Mb/sec
66X = 10.0 Mb/sec (Also known as Class 10 for SD Cards)
80X = 12.0 Mb/sec
90X = 15.0 Mb/sec
133X = 20.0 Mb/sec
Why do we need different or higher speeds cards?
This is mainly due to the advancement of our digital devices, especially digital cameras, camcorders and music devices. As manufacturers develop higher and higher spec devices (i.e. higher resolution cameras and more intense multi-media functions), they are creating increasingly larger amounts information to store pictures, movies, music and so on. This in turn takes longer to record onto the memory card. For example if you have ever used a high megapixel camera with a standard speed card you may have noticed the time lag between pressing the shutter button and being able to take the next picture. This lag or delay, in most cases, is caused by a slow write speed. Similarly, copying your photos to your PC could take time too and is caused by a slow read speed.
So who really needs high-speed memory cards?
Professional photographers and enthusiasts using professional grade cameras such as digital SLR’s should use high-speed memory cards of at least 40X speed. If you own a camera with a megapixel rate above ten million pixels, you will certainly benefit from a card with a higher speed rating. If you’re like most of us using a compact camera under ten million pixels, you’ll get great performance from standard cards with 25X or more.
Those using digital camcorders and devices recording MP3 music or video will also benefit from higher speed cards. It used to be where very few people would actually benefit from very high-speed cards. Typically only professionals who used expensive, specialized products benefited, but it’s fast becoming a requirement on many of the latest PDA’s, Cameras, phones and other mobile devices to make use of the extra speed made available by high speed cards.
People using high speed memory cards with equipment that has been on the market a while may not notice any difference in performance, but this has more to do with the limitations of the device than the flash card itself. This is because not only does your memory card have a maximum speed rating, but your camera or mobile phone will also have its own speed rating. When these products are combined, they’ll work at the “slowest common denominator” e.g. if you use a 12X flash card in a camera with a designed for a maximum of 8X speed, you’ll be transferring data at the slower 8X speed.
You should always check the capacity of your device before splurging on mega fast cards, but determining the speed compatibility of your device can be tricky. Most manuals just don’t tell you what speed of flash card you should use, now that would be far too easy, but they do tell you to buy their brand, which isn’t much help! So a general rule of thumb, if your camera is less than three megapixels the speed rating of the flash card doesn’t matter much. Most modern cameras have the ability to support far higher speeds than the cards available to purchase today, therefore, if speed is of importance, go for a faster card. Most mobile phones are fine with standard speed cards although some newer models will benefit from higher speed cards but not generally over 60X speeds. Hope this info helps you pick your next SD Card wisely.