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Thread: Relevance of High Speed SD Card

  1. #1

    Default Relevance of High Speed SD Card

    Sandisk has various SD cards at different speeds. For eg Extreme SDXC card at 45 MB/sec , Extreme Pro SDHC/SDXC card at 95MB/sec... earlier cards at 30 MB/sec etc.

    The promo video indicates a higher speed card has the following advantages
    1) continuous burst speed shooting
    2) HD video recording
    3) higher speed transferring image fr card to computer


    Question 1
    While the speed of the card has increased substantially from 30 MB/sec to 95 MB/sec, does it substantially help in burst speed shooting and video recording? I have not heard / read any sifu / veterans complain their 30 MB/sec or 45 MB / sec cards.

    Question 2
    Is the limitation primarily by the body, instead by the card? Assuming I use the minimum speed card specified by manual. For eg I am using Nikon D7000, and Class 6 Card at 20 MB/sec. Will my camera be able to leverage on the highest speed card like 95 MB/sec?

    Many thanks!!

  2. #2
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    Default Re: Relevance of High Speed SD Card

    From my experience, say i am shooting 5 frame per second, writing Raw + L means about 30mb per frame, my memory card will have to read/write at a 150 mb/second? but my camera body will offload some of the space before writing, thats why sometime if u using a class 4 memory card, you continous burst mode will stop halfway..

    an experience i encounter, i have been scamm for a fake 16gb class 6 memory card, suppose to be design for HD movie recording. however, at the 7-8 min point of the video, my camera shows "recording stop automatically", later i found out that i need a real class 6 at least, or the claass 10 card for really smooth recording/shooting.
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  3. #3

    Default Re: Relevance of High Speed SD Card

    Thanks..

    Say my camera can take 6 frame per second, with a card specified by the manual say Class 6 20 Mb/sec.

    I can understd if I use a lower speed card like Class 4, or a fake SD card, the camera may not be able to perform at 6 frame per second.

    If i use a SD card with 95 Mb/sec, I am still limited by 6 frames per second.

    Can I conclude a higher speed card is only as good as the minimum speed card specified by the camera manual for the camera to perform optimally?

    Reminds me, with respect to car fuel, a higher octane fuel 97 does not necessarily perform better than a lower octane fuel 95, for most cars, unless its Ferrari equivalent. In this case, maybe only top end camera user like Nikon D3 or D4 will then benefit fr a higher speed card.
    Last edited by samueltan99; 1st March 2012 at 11:20 AM.

  4. #4

    Default Re: Relevance of High Speed SD Card

    Quote Originally Posted by samueltan99 View Post
    Thanks..

    Say my camera can take 6 frame per second, with a card specified by the manual say Class 6 20 Mb/sec.

    I can understd if I use a lower speed card like Class 4, or a fake SD card, the camera may not be able to perform at 6 frame per second.

    If i use a SD card with 95 Mb/sec, I am still limited by 6 frames per second.

    Can I conclude a higher speed card is only as good as the minimum speed card specified by the camera manual for the camera to perform optimally?

    Reminds me, with respect to car fuel, a higher octane fuel 97 does not necessarily perform better than a lower octane fuel 95, for most cars, unless its Ferrari equivalent. In this case, maybe only top end camera user like Nikon D3 or D4 will then benefit fr a higher speed card.
    Hi, I think the analogy of car octane type is not exactly correct with regards memory
    cards and camera performance.A camera is an electro-mechanical-optical system,the electronic system or circuit has a finite processing time,by that we mean each electronic
    component from ICs like processor/controller ,memory and associated components takes a certain amount of time to complete it's tasks.

    Take for example continuous shooting, what happens is when the in camera buffer
    memory is full,it has to transfer it's content to the memory card before shooting another
    series of photos.As you may have experienced,either the camera momentarily stops or
    the frame rate slows down.All these tasks has to be completed before another series
    of photos can be taken or processed.Hence the delay.When this is encounted say a photo oppotunity presents itself you may be unable to operate the camera and miss the shot.The video problem is a matter of moving large amount of data and hence more processing time.So a faster data transfer rate (read/write) is neccessary but bear in mind the inherent or native processing speed of the controller circuits.Having a class 10
    memory card may not improve the processing speed if they are not compatable.That is
    camera electronics cannot take advantage of the faster data rate of a class 10 card.You
    may get an improvement but not significant.All in all what it means is you get to fire more
    shots and not miss the moment.That is the more important issue.The downside is the extra cost of such cards.If getting the shot matters then a faster card is the way to go.Hope this explaination is adequate.

  5. #5

    Default Re: Relevance of High Speed SD Card

    Have you consider the inbuilt memory that buffers the images before writing to your external memory cards ? While it's true that should external memory card can't keep up with the processing speed where these images are delivered into the card, the bottleneck may be the external memory. However, ask yourself, how often do you keep on depress on the shutter release in continuous mode without release. Without pauses in the middle to re-compose, to re-think, to adjust settings. Adding your human interaction time involved, you will find that most of the time, having external memory the same transfer speed as what your camera can produce may often be an overkill requirement.

    My advice is just go with mainstream memory cards that can faster enough for your camera to store, where you don't need to wait for >1s to store an image (already very slow) and save your money for something else that will improve your experience using the camera. I find it pretty pointless to go for the most high end memory at times, unless you will really benefit from it a lot during your workflow. For e.g.: In comparison, I rather spend the memory to get a SSD to enhance my whole processing workflow as oppose to a super fast memory card which offers little benefit to your workflow, should you are a landscape photographer, or event photographers. I suppose even if you are taking photos of F1 cars speeding past, a high speed memory card is not going to be extremely helpful.
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  6. #6

    Default Re: Relevance of High Speed SD Card

    I think digital cameras and computers are inherently similar nowadays cos we talks about, processing speed, transfer speed, etc. from my experience with computers I think your way of thinking is correct, the limitation is where the bottleneck is. Faster memory card would not help if the bottle neck is with the camera's ability to process and transfer the data captured by the sensor.

  7. #7

    Default Re: Relevance of High Speed SD Card

    Quote Originally Posted by David Kwok View Post
    Have you consider the inbuilt memory that buffers the images before writing to your external memory cards ? While it's true that should external memory card can't keep up with the processing speed where these images are delivered into the card, the bottleneck may be the external memory. However, ask yourself, how often do you keep on depress on the shutter release in continuous mode without release. Without pauses in the middle to re-compose, to re-think, to adjust settings. Adding your human interaction time involved, you will find that most of the time, having external memory the same transfer speed as what your camera can produce may often be an overkill requirement.

    My advice is just go with mainstream memory cards that can faster enough for your camera to store, where you don't need to wait for >1s to store an image (already very slow) and save your money for something else that will improve your experience using the camera. I find it pretty pointless to go for the most high end memory at times, unless you will really benefit from it a lot during your workflow. For e.g.: In comparison, I rather spend the memory to get a SSD to enhance my whole processing workflow as oppose to a super fast memory card which offers little benefit to your workflow, should you are a landscape photographer, or event photographers. I suppose even if you are taking photos of F1 cars speeding past, a high speed memory card is not going to be extremely helpful.
    I never know that we can change the internal memory.

  8. #8

    Default Re: Relevance of High Speed SD Card

    Hi, I forgot to mention camera operating speed is also dependent on the picture resolution selected.If say highest resolution of a 12MP is chosen and RAW + jpeg
    then speed is slower as the camera memory buffer is filled up faster.This will limit the
    number of frames you can shoot.If you know the buffer memory,you can also caculate
    how many frames can be stored before camera has to slow down and dump to SD card.

    In essence if you don't need big enlargements and can make do with 5X7 or 8X10 in.
    The camera can perform faster and the number of continuos shots increased by selecting
    good or better instead of best picture quality.A cost effective solution.

  9. #9

    Default Re: Relevance of High Speed SD Card

    So does the "Class" of the SD cards determine this "processing speed"? What is the general recommended one anyway?

  10. #10

    Default Re: Relevance of High Speed SD Card

    Quote Originally Posted by blackcookie View Post
    So does the "Class" of the SD cards determine this "processing speed"? What is the general recommended one anyway?
    Hi, No not totally,as you have to consider the native speed of the camera system.But having a faster SD card is essential for video recording purpose as the camera is not likely to stall or pause between memory transfer
    operations.If for continuous shooting like a reportage style action you are not likely to miss a shot which really matters.How precious is a moment to you.Most freebie SD cards supplied are class4 ,they are adequate for most ordinary situations where you "think" before you shoot artistic type shots but for the unexpected,faster cards are an advantage but have to take into account picture resolution and continuos
    frame rates of the particular camera and buffer memory in the camera.Most people recommend a class10 for smooth video capture.Hope that helps.An analogy is like passing the bucket,if the receiver is fast (SD card)
    the operation is completed sooner.

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