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Thread: SD Cards Speed Ratings

  1. #1

    Default SD Cards Speed Ratings

    Hi, just want to find out more about SD cards to clear some misunderstanding. I did some research on it before but I thought that it's better to hear what others think too.

    Through researching, I found out that for videoing requires at least a class 6 SD card. However, currently I own 2 different SD cards where both are class 10, 16GB, SanDisk but one of the writing speed is 30mbps while the other one is 45mbps.

    I know that if taking stills, there's a difference as the 45mbps would definitely be faster for the stills to be transferred into the card so you can playback rather than the 30mbps which should take slightly longer for the playback.

    But does it matter if I use any of the cards for videoing?

  2. #2


    No because both are above the minimum speed.

  3. #3


    The Source matters too

  4. #4

    Default Re: SD Cards Speed Ratings

    Thanks for the reply but what do you mean by 'Source'?

  5. #5


    Quote Originally Posted by Jhree View Post
    Thanks for the reply but what do you mean by 'Source'?
    The device. Certain devices do not support high speed data transfer, so buying a fast card might not be the best choice

  6. #6

    Default Re: SD Cards Speed Ratings

    Check this out:

    The class rating system has its limitations, but it can be a handy guide to the practical capabilities of different cards. A class 2 rating means the card is guaranteed to be fast enough for standard-definition video recording, while classes 4 and 6 are fast enough for Full HD video (which one you need will depend on the bit rate of the video format you’re using).

    The highest rating, class 10, is faster than required for any modern video standard: rather, it’s aimed at stills photographers. The idea is to minimise the time it takes to write a photograph to the card, so you can take multiple shots in rapid succession without having to wait around for each one to be stored.

    It may seem counter-intuitive that capturing still images requires a faster card than shooting video, but Full HD footage isn’t as space-hungry as you might imagine. Despite the “high-definition” terminology, each HD frame has a comparatively low resolution of just over two megapixels. Plus, since consecutive frames of a video are often extremely similar, clever compression techniques can be used to store moving images efficiently. A data rate of 4-6MB/sec is ample for continuous shooting.


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