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Looking to buy a new memory card for my Samsung dv100.
After reading the manual, asking samsung support and searching the web,
I still don't understand whether buying UHS1 card is an "overkill" for this camera model.

What advantages would buying a UHS1 card have?

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To those closing as off topic because it relates to video. This is also useful for still photography as it will change the rate at which the buffer clears when taking still photos as well. –  AJ Henderson Dec 28 '13 at 19:03
    
We also have a general version of this question here: How can I know what speed card to get for my camera? –  mattdm Dec 28 '13 at 19:10
    
@mattdm - that's similar, but I'm not sure if it is the same. This is asking what the advantages of a faster card are. That one only asks how to determine what card speed to get. I think we could modify either question to cover both situations well, but currently they are asking slightly different things and I don't think the existing answers cover this one completely. –  AJ Henderson Dec 28 '13 at 19:12
    
    
The ultimate question would be, "Where can I find a list that tells the maximum speed memory card of which my camera is capable of taking advantage?" Unfortunately, to the best of my knowledge, no such list exists. Rob Galbraith's list was once pretty good, but doesn't seem to have been updated in years. And trying to access some links to the site now can be problematic. –  Michael Clark Dec 28 '13 at 23:14

2 Answers 2

up vote 2 down vote accepted

When taking photos or shooting video, the image data is offloaded to a high speed internal cache for processing. There is a limited amount of space available in this cache and so to empty it out, files are written off to the memory card to make room for more pictures or frames of video.

If you take photos or video at a rate that exceeds the memory card's ability to save, eventually the cache will fill up and it will not be possible to store any more images. Using a faster memory card allows for the cache to be cleared faster and thus, you can shoot for longer before the cache fills (assuming the camera supports writing to and from the cache simultaneously) and also makes it so that when the cache does fill, it can be empties more quickly.

The one caveat to this is that if a particular type of card is not supported by the camera or the speed of the card exceeds the speed of the card slot, then there would be no gain by moving to a faster card and it could actually result in the card not working potentially.

So, to determine if the UHS1 card would be an upgrade, you need to verify that your camera supports UHS1 cards and that it can make use of the speed. If it can (or if it supports a speed faster than your current, but slower than UHS1) then the upgrade will allow for your cache to be cleared quickly and increase the available video recording time (if it was previously cache limited), increase the number of photos that can be shot in a burst (if the camera supports writing to the SD card while the cache is being written too) and faster clearing of the cache when not shooting (gets ready to shoot a burst again faster).

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Thanks. How could I determine whether the camera support writing to and from the cache simultaneously, and the speed itself? Have searched for such info but found nothing . –  Gal Margalit Jan 3 at 14:15
    
@GalMargalit - the best bet, experiment. Try shooting the longest burst you can, figure out the size of the images that were stored. Change your resolution and repeat. If you get a larger total size of files when you have smaller files, then it is writing out as it goes and since it takes longer for data to build up, it will take more total data before the buffer fills. If they are nearly the same total size, then it is probably not. It's like having a bathtub that can only drain so fast. –  AJ Henderson Jan 3 at 14:18
    
If it is completely stopped (no writing) then slow or fast water will still fill in the same amount of water since no water is being lost. If it drains slowly, then filling the tub slowly will take a much larger amount of water than if you fill the tub quickly. If you time it, the difference should also give you the approximate rate at which the cache can be emptied, though the manual should also indicate the speed of the card reader in the camera. –  AJ Henderson Jan 3 at 14:18
    
Thanks again! Will try & update –  Gal Margalit Jan 3 at 14:19
    
Buying a UHS card did solve my problem :) –  Gal Margalit Feb 17 at 18:53

Here is some reasoning based on numbers:

  • You don't need a fast card for video. It is generally advised to use at least class 6 for video recording on a consumer AVCHD device:

    Max recording bit rate of AVCHD 2.0 is 28 Mbit/s and minimum write speed of a class 6 card is 48 Mbit/s, this should provide enough headroom even with an almost full card.

  • Your camera doesn't mention UHS-I in it's specs, only SDHC. So if you use a UHS-I card, it will be limited below 25 MByte/s, which is still faster than many class 10 cards.

    For shooting pictures in continuous (burst) mode: when the high speed memory buffer of the camera fills up, you will continue to shoot below 25 MByte/s, about 3 images per second or less.

  • Using high speed card reader, transferring a full 32 GB UHS-I Class 1 card will take you maximum about an hour.

Take a look at this list of some bitrates for cards, cameras and video formats.

                        MEGABYTE/S    MEGABIT/S

---- 1080p30 Consumer ----
          AVCHD              3.0         24     also in some prosumer cams
        AVCHD 2.0            3.5         28
------ 1080p30 Pro -------
          DNxHD             9-28     36-220
         ProRes            12-41    100-330
        AVC-Intra           6-55     50-440
  Compresed CinemaDNG         60        480     roughly, as seen in BMPCC
        12-bit Raw            89        712    

---- 16 Mpix Picture -----                      File size per picture
  Uncompressed 14-bit Raw     27        214
   Lossless Raw (NEF,CR2)     20        160     roughly
           JPEG                8         64     roughly

------ SD Card Class -----                      
          Class 2            2.0         16     Card class is the minimum speed
          Class 4            4.0         32     of the card according to the spec,
          Class 6            6.0         48     measured with empty card
          Class 10          10.0         80
------- SD Card BUS ------                      
            SD              12.5        100     Bus speed: speed of interface
          SDHC/XC           25.0        200     between device and card,
                                                data transfer speed is lower.
--- UHS SD Card Class ----
    UHS Speed Class 1       10.0         80
    UHS Speed Class 3       30.0        240
---- UHS SD Card BUS -----
       SDXC UHS-I         50/104    400/832
       SDXC UHS-II       156/312  1248/2496
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Thanks for your reply! –  Gal Margalit Feb 19 at 16:40
    
Actually have bought SDHC, mistakenly I wrote UHS 1 –  Gal Margalit Feb 19 at 16:52

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