SD card speeds?

Discussion in 'Digital Photography' started by Terry Pinnell, Dec 17, 2007.

  1. I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    Does anyone know of a good reference source for that info please? Or a
    supplier that *does* quote that?

    --
    Terry, East Grinstead, UK
    Terry Pinnell, Dec 17, 2007
    #1
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  2. Terry Pinnell

    Marty Fremen Guest

    Terry Pinnell <> wrote:
    >
    > I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    > of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    > Does anyone know of a good reference source for that info please? Or a
    > supplier that *does* quote that?


    The 150x etc only seems to refer to read speed. For the all-important write
    speed (important for cameras anyhow) you need to read some reviews, since
    accurate figures rarely seem to be availale on suppliers' sites.
    Furthermore, read speed seems to bear little relation to write speed, for
    instance I bought a "MyMemory" own brand 133x SD card and its write speed
    was only about 2-3 MB/sec, whereas other brand cards of that spec have
    anything up to 20 MB/sec write speed. In practice, the MyMemory 133x speed
    card turned out to be slower than my Sandisk 33x card.

    Looking through my bookmarks, you might try
    http://www.dcareview.com/tables.html
    Marty Fremen, Dec 17, 2007
    #2
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  3. Terry Pinnell wrote:
    > I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    > of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    > Does anyone know of a good reference source for that info please? Or a
    > supplier that *does* quote that?


    A Google search on <sd card speeds> reveals:

    http://www.gadgetspage.com/cameras/understanding-sd-flash-memory-card-speeds.html

    Which contains further links to actual speed tests with particular
    cameras.

    A general rule is that if the card is slow, it won't advertise its
    speed.

    The manufacturers sites also have speed info, but I'd much rather
    trust a third party test. Also, relatively few consumer devices
    require high speed cards.

    High speed cards are more expensive, since they use "single-level"
    bit storage, or one storage cell per bit, as opposed to "multi-level"
    storage, which currently stores two bits per cell (by storing four
    discrete levels of charge per cell). Single-level storage requires
    either more chips or bigger chips for the same amount of storage,
    hence the higher cost.

    From a practical point of view, the "sweet spot" cards of 1GB and
    2GB can usually be found at speeds of 30x and up for under $10 per
    gigabyte if you shop carefully. (There has been a glut of capacity
    in the flash memory market for almost a year, now.)

    -michael

    "The wastebasket is our most important design
    tool--and it's seriously underused."
    Michael J. Mahon, Dec 17, 2007
    #3
  4. "Michael J. Mahon" <> wrote:

    >Terry Pinnell wrote:
    >> I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    >> of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    >> Does anyone know of a good reference source for that info please? Or a
    >> supplier that *does* quote that?

    >
    >A Google search on <sd card speeds> reveals:
    >
    >http://www.gadgetspage.com/cameras/understanding-sd-flash-memory-card-speeds.html
    >
    >Which contains further links to actual speed tests with particular
    >cameras.
    >
    >A general rule is that if the card is slow, it won't advertise its
    >speed.
    >
    >The manufacturers sites also have speed info, but I'd much rather
    >trust a third party test. Also, relatively few consumer devices
    >require high speed cards.
    >
    >High speed cards are more expensive, since they use "single-level"
    >bit storage, or one storage cell per bit, as opposed to "multi-level"
    >storage, which currently stores two bits per cell (by storing four
    >discrete levels of charge per cell). Single-level storage requires
    >either more chips or bigger chips for the same amount of storage,
    >hence the higher cost.
    >
    > From a practical point of view, the "sweet spot" cards of 1GB and
    >2GB can usually be found at speeds of 30x and up for under $10 per
    >gigabyte if you shop carefully. (There has been a glut of capacity
    >in the flash memory market for almost a year, now.)


    Thanks both, very helpful. I'll follow up those links.

    --
    Terry, East Grinstead, UK
    Terry Pinnell, Dec 17, 2007
    #4
  5. Terry Pinnell

    Bob Guest

    "Marty Fremen" <> wrote in message
    news:Xns9A09D2479F463C9A6@213.239.142.64...
    > Terry Pinnell <> wrote:
    >>
    >> I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    >> of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    >> Does anyone know of a good reference source for that info please? Or a
    >> supplier that *does* quote that?

    >
    > The 150x etc only seems to refer to read speed. For the all-important
    > write
    > speed (important for cameras anyhow) you need to read some reviews, since
    > accurate figures rarely seem to be availale on suppliers' sites.
    > Furthermore, read speed seems to bear little relation to write speed, for
    > instance I bought a "MyMemory" own brand 133x SD card and its write speed
    > was only about 2-3 MB/sec, whereas other brand cards of that spec have
    > anything up to 20 MB/sec write speed. In practice, the MyMemory 133x speed
    > card turned out to be slower than my Sandisk 33x card.
    >
    > Looking through my bookmarks, you might try
    > http://www.dcareview.com/tables.html


    Excuse my ignorance. What is the importance of SD card speeds. Does it
    affect the quality of photos or transferring shots to PC or something else?
    Bob, Dec 18, 2007
    #5
  6. Bob wrote:
    >
    > "Marty Fremen" <> wrote in message
    > news:Xns9A09D2479F463C9A6@213.239.142.64...
    >
    >> Terry Pinnell <> wrote:
    >>
    >>>
    >>> I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    >>> of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    >>> Does anyone know of a good reference source for that info please? Or a
    >>> supplier that *does* quote that?

    >>
    >>
    >> The 150x etc only seems to refer to read speed. For the all-important
    >> write
    >> speed (important for cameras anyhow) you need to read some reviews, since
    >> accurate figures rarely seem to be availale on suppliers' sites.
    >> Furthermore, read speed seems to bear little relation to write speed, for
    >> instance I bought a "MyMemory" own brand 133x SD card and its write speed
    >> was only about 2-3 MB/sec, whereas other brand cards of that spec have
    >> anything up to 20 MB/sec write speed. In practice, the MyMemory 133x
    >> speed
    >> card turned out to be slower than my Sandisk 33x card.
    >>
    >> Looking through my bookmarks, you might try
    >> http://www.dcareview.com/tables.html

    >
    >
    > Excuse my ignorance. What is the importance of SD card speeds. Does it
    > affect the quality of photos or transferring shots to PC or something else?


    For some cameras, it can affect the time required to write a photo
    to the card. If shooting multiple pictures, it can therefore affect
    the picture taking rate.

    Some video recording modes also require a minimum write speed to
    keep up.

    Frankly, the speed issue is very badly handled by both card and
    camera manufacturers. The "x" notation is actually related back
    to audio CD speeds, so you can see how out of sync with today's
    requirements it is!

    Card manufacturers should be required to spec sustained (large
    file) read and write speeds in MB/sec, and camera manufacturers
    should express their minimum requirements in the same units.

    As with gasoline, if the speed limiter is your camera, then using
    a faster card does not help--it just costs more.

    -michael

    "The wastebasket is our most important design
    tool--and it's seriously underused."
    Michael J. Mahon, Dec 18, 2007
    #6
  7. Terry Pinnell

    Bob Guest

    "Michael J. Mahon" <> wrote in message
    news:...
    > Terry Pinnell wrote:
    >> I want to buy some new SD cards, 2GB and maybe 4 GB. But the majority
    >> of the supplier sites seem to show no data on speeds (50x, 150x, etc).
    >> Does anyone know of a good reference source for that info please? Or a
    >> supplier that *does* quote that?

    >
    > A Google search on <sd card speeds> reveals:
    >
    > http://www.gadgetspage.com/cameras/understanding-sd-flash-memory-card-speeds.html
    >
    > Which contains further links to actual speed tests with particular
    > cameras.
    >
    > A general rule is that if the card is slow, it won't advertise its
    > speed.
    >
    > The manufacturers sites also have speed info, but I'd much rather
    > trust a third party test. Also, relatively few consumer devices
    > require high speed cards.
    >
    > High speed cards are more expensive, since they use "single-level"
    > bit storage, or one storage cell per bit, as opposed to "multi-level"
    > storage, which currently stores two bits per cell (by storing four
    > discrete levels of charge per cell). Single-level storage requires
    > either more chips or bigger chips for the same amount of storage,
    > hence the higher cost.
    >
    > From a practical point of view, the "sweet spot" cards of 1GB and
    > 2GB can usually be found at speeds of 30x and up for under $10 per
    > gigabyte if you shop carefully. (There has been a glut of capacity
    > in the flash memory market for almost a year, now.)
    >

    Thank you Michael.
    Bob, Dec 18, 2007
    #7
  8. Bob wrote:
    > Excuse my ignorance. What is the importance of SD card speeds. Does
    > it affect the quality of photos or transferring shots to PC or
    > something else?


    No, yes, and yes :)
    Long answer: It has nothing to do with quality of photos. And normally the
    speed won't affect your normal photo shooting either.
    However in cases where the camera needs to store a lot of information in a
    very short time then a card with a faster write speed may be able to keep up
    with the data stream while a slower card could become a bottle neck and slow
    down the speed with which you can shoot photos. Typical scenario would be
    shooting in quick succession e.g. in burst mode (up to 10 photos a second)
    and maybe even using RAW (10MB+ per photo). That will quickly push any card
    to its limits. Of course a faster write speed will only benefit you, if your
    camera does support that faster speed, too.

    A faster read speed will accelerate the download to your computer provided
    your card reader knows how to utilize that faster card speed.

    jue
    Jürgen Exner, Dec 18, 2007
    #8
  9. Terry Pinnell

    Bob Guest

    "Jürgen Exner" <> wrote in message
    news:yDH9j.19942$1R1.2096@trndny02...
    > Bob wrote:
    >> Excuse my ignorance. What is the importance of SD card speeds. Does
    >> it affect the quality of photos or transferring shots to PC or
    >> something else?

    >
    > No, yes, and yes :)
    > Long answer: It has nothing to do with quality of photos. And normally the
    > speed won't affect your normal photo shooting either.
    > However in cases where the camera needs to store a lot of information in a
    > very short time then a card with a faster write speed may be able to keep
    > up with the data stream while a slower card could become a bottle neck and
    > slow down the speed with which you can shoot photos. Typical scenario
    > would be shooting in quick succession e.g. in burst mode (up to 10 photos
    > a second) and maybe even using RAW (10MB+ per photo). That will quickly
    > push any card to its limits. Of course a faster write speed will only
    > benefit you, if your camera does support that faster speed, too.
    >
    > A faster read speed will accelerate the download to your computer provided
    > your card reader knows how to utilize that faster card speed.
    >
    > jue


    Got it. Thanks.
    Bob, Dec 18, 2007
    #9
  10. Terry Pinnell

    Marty Fremen Guest

    "Michael J. Mahon" <> wrote:
    > For some cameras, it can affect the time required to write a photo
    > to the card. If shooting multiple pictures, it can therefore affect
    > the picture taking rate.


    It's not just the picture taking rate but the picture-to-review delay - you
    can't examine a picture at full resolution until it has finished writing to
    the card. Having to wait a few seconds until you can verify that you got
    the shot in the can (e.g. zooming the shot to check focus, or checking for
    highlight saturation) is irritating and may even mean you lose the chance
    to have a second go. In my case I'm writing an 18MB raw+jpeg so card speed
    it critical, however even on point and shoots with 2MB jpegs I find the
    shot-to-playback delay can be improved noticably with a faster card.
    Getting the review delay down from say 2.5 secs to 1.5 sec may seem trivial
    but subjectively at least it makes a difference to the picture taking
    experience.
    Marty Fremen, Dec 18, 2007
    #10
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