What Is Memory Card Speed?
In a few short years since the launch of the first 4Mb flash
memory card, the number of flash memory 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 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 20X represents a standard speed, 20X to 40X is mid-high speed
and over 40X is high speed. The chart below shows the relationship
between the two figures.
8X = 1.2 Mb/sec 12X = 1.8 Mb/sec 20X = 3.0 Mb/sec 25X = 3.8
Mb/sec 30X = 4.5 Mb/sec 40X = 6.0 Mb/sec 60X = 9.0 Mb/sec 66X =
10.0 Mb/sec 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 three
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 3 million pixels, you'll get great performance from
standard cards with 12X or more.
Those using digital camcorders and devices recording MP3 music
or video will also benefit from higher speed cards. It used to be
the case 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
splashing out 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,
PDA's and Satellite Navigators are fine with standard speed cards
although some newer models will benefit from higher speed cards but
not generally over 60X speed.
About the Author
Article by Iggy Quazi director of
Ecommerce business Mouse2House based in Essex, England stocking a
wide range of digital imaging devices. For more info see
http://www.mouse2house.co.uk for the
latest digital media products. For Flash Memory Cards visit
http://www.mouse2house.co.uk/index.php?CatURN=637 |