Video Production Stack Exchange is a question and answer site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation. It only takes a minute to sign up.
Sign up to join this community
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?
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).
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