{"id":874,"date":"2014-11-22T19:55:10","date_gmt":"2014-11-22T19:55:10","guid":{"rendered":"http:\/\/www.kevindavisphoto.com\/blog\/?p=874"},"modified":"2014-11-22T20:07:21","modified_gmt":"2014-11-22T20:07:21","slug":"memory-card-speed-and-card-reader","status":"publish","type":"post","link":"https:\/\/www.kevindavisphoto.com\/blog\/memory-card-speed-and-card-reader\/","title":{"rendered":"Memory Cards – What Speed Do I Need?"},"content":{"rendered":"
\"CF,<\/a>
CF, SD, and micro SD memory cards<\/figcaption><\/figure>\n

The photo here shows some of the memory cards I have used in my digital cameras.\u00a0 The oldest is the SD card at center, rated at 20MB\/sec.\u00a0 The newest and fastest is at the top (SanDisk, CF card), rated at a maximum speed of 120 MB\/sec.<\/p>\n

Historically, CF cards have supported faster data transfer (read and write) than SD cards.\u00a0 The reason is simple – a CF card can transfer 16 bits all at once, whereas a SD card can only transfer 4 bits at once.\u00a0 Count the electrical contacts on an SD card \u2013 there are 9 pins.\u00a0 Count the pin holes on a CF card \u2013 there are 50 pins.<\/p>\n

\"SD-class-symbols\"<\/a>Standard SD cards (SDHC, SDXC) are deemed UHS class I.\u00a0 A recent evolution of the SD card format has introduced SDXC UHS class 3.\u00a0 These cards have 7 additional electrical contacts and allow faster data transfer up to a theoretical limit of 300 MB\/sec (equal to the limit for CF cards).\u00a0 These cards should be backward compatible with older cameras that support only the 9-pin UHS-I interface, but you will not see the speed advantage of the faster interface.<\/p>\n

For historical reasons, the maximum speed of a memory card may be shown as a multiplier, such as 100x, 266x, etc.\u00a0 The baseline is 150 KB\/sec.\u00a0 So 300x means 45 MB\/sec (45,000 KB\/sec).<\/p>\n

Instead of an”x” rating, CF cards will typically be labelled with a simple speed rating in MB\/sec.\u00a0 For SD cards, a speed class rating is newer than the old \u201cx\u201d rating . \u00a0Class 6 means that the card can support at least 6 MB\/sec.\u00a0 Class 10 means 10 MB\/sec or more.<\/p>\n

The speed class rating has been supplanted by the UHS speed class rating (Ultra High Speed).\u00a0 UHS Class 1 means the card will support a write speed of 10 MB\/sec or better.\u00a0 UHS Class 3 (a.k.a. U3) means the card will support a write speed of 30 MB\/sec or better.<\/p>\n

\u00a0How fast does a memory card need to be?<\/h2>\n

Writing to the card and reading from the card are really two different considerations.\u00a0 If you\u2019re capturing 1080 HD compressed video, a momentary burst up to 30 MB\/s is possible, but the sustained data rate is not that high.\u00a0 You need a Class 10 card.\u00a0 For 4K ultra-HD video recording, you need UHS Class 3. \u00a0If your card can\u2019t quite keep up, your camera will likely abort recording.<\/p>\n

If you are a sports photographer, capturing ten images per second may amount to 300 MB\/sec but this speed need not be maintained constantly.\u00a0 If your card cannot keep up, your camera will report \u201cbusy\u201d for a second or two, during which new images cannot be captured.<\/p>\n

At the end of the day, you need to upload the photos and video to a computer.\u00a0 That\u2019s when you want to have the fastest speed reading from a card.<\/p>\n

\u00a0Card Readers<\/h2>\n

For years, photographers relied upon Rob Galbraith (http:\/\/robgalbraith.com<\/a>) for his work measuring the read\/write speeds of both memory cards and card readers.\u00a0 Then Rob moved to a full-time job and could no longer maintain the database.\u00a0 Recently there has been an update, seen here by PhotoShelter:<\/p>\n

http:\/\/blog.photoshelter.com\/2014\/10\/photoshelter-card-reader-database-why-you-should-upgrade\/<\/a><\/p>\n

Three tables are presented.\u00a0 The first shows data transfer rate when reading from memory cards to a 2013 Mac Pro.\u00a0 The second is the same, but using a 2014 Macbook Pro.\u00a0 The third table regards XQD cards, which are new and relatively uncommon (notably, the Nikon D4 supports XQD cards). \u00a0Higher number means faster data copy – the numbers are MB\/sec.<\/p>\n

The fastest card readers for (SD and CF cards) are:<\/p>\n