SD cards on the market are getting faster and faster which is a great thing,,, right? Most people just assume it must be a good thing and therefore will spend money (and the price goes up considerably) for faster cards, especially if they are working with their new expensive dslr cameras. But is it something you really need? What are advantages?
The “speed” of you card is in reference to it’s write speed. How fast can data be transferred from the camera onto your card for storage. This comes into play when you attempt to photograph multiple shots one after another (for instance sports photos). When data is being captured faster than the SD card’s write (transfer) speed, the image data goes into your camera’s buffer (temporary memory) and is then weaned into the memory card. If your data capture exceeds the space in the buffer your camera will stop taking photos and will only allow further shutter releases as data moves from the buffer onto the card. This could be the difference between capturing the “big moment” and not.
What are the benefits?
- Do faster sd cards allow you to shoot faster? (no, they do not)… Your camera can only shoot as fast as it’s shutter mechanism allows. This is a mechanical ceiling that cannot be changed.
- Can I shoot more continuous photos in a row using a faster sd card? Yes, but how much varies a lot dependent on file sizes. For instance with my camera, doubling my card speed will not drastically increase the number of photos I can shoot continuously in RAW,, but in jpg I get a significant increase. As the photos are captured the data total piles up quickly,,, much more quickly than the card is writing, so the buffer is used. When the buffer fills the camera stops shooting. If you are using a faster sd card, then it probably took in a couple more photos than it would have prior, thus the buffer takes a bit longer to fill, but until cards can take in data as fast as the camera produces it, then there will still always be a ceiling. The long and short of it is, faster cards will increase continuous shooting ability, but how much depends on the megapixel size of your camera’s photos.
- Is recovery time decreased once the buffer is filled? Yes. Once the buffer becomes full, a faster card will allow you to “drain” the buffer faster, thus making room for another photo. So while the number of continuous frames may not be greatly increased, my ability to recover buffer space and shoot again is greatly increased.
Analogy: Think of it like this. You are pouring liquid into a funnel that sits atop a jar. The jar is the SD card (storage), the funnel is the buffer. Liquid moves through the “tip” of the funnel into the jar at a slow speed (transfer speed), but you are able to pour large amounts of liquid directly into the funnel which then moves the liquid into the jar at whatever speed the “tip” allows. If you pour so much liquid into the funnel that it overflows you must stop pouring the liquid (ie: the camera must stop shooting images). If I use a funnel with a wider “tip” then I can pour more liquid before the funnel becomes full, as more liquid has moved into the jar before the liquid reaches the funnel’s rim; however, it will also drain much faster allowing me to more quickly start pouring more liquid back into the funnel. Does that help any? (Files size would equate to how fast you’re pouring your liquid)
Speed Ratings: The sd cards are usually rated (class 2, 4, 6 and 10; these respectively guarantee that the card can sustain a write speed of 2MB/sec, 4MB/sec, 6MB/sec or 10MB/sec.) and while this makes it easy to see what cards are relatively slow, in today’s super fast transfer rate world, it tells you very little about which cards are really fast. You must therefore look for a manufacturer’s statement of transfer speed by mb/s. (example: my newest cards are 60 mb/s, while my oldest cards are a mere 6 mb/s).
You may also see cards marked with a UHS-1 rating. This indicates compatibility with the Ultra-High Speed SD standard (a relatively new standard at the time of this writing). UHS-1 has a theoretical maximum transfer speed from 104MB/sec to 312MB/sec. However, UHS-1 certified rating does not guarantee your card is fast, only that it’s compatible – a UHS-1 certified card could be slower than an uncertified one.
Should you buy faster sd cards? That really depends on whether you find yourself filling your camera’s buffer often.
- If you have never filled your buffer, than no, don’t waste the money.
- If you’re into fast shooting subject matter like sports then yes, it’s a good investment to help prevent you from missing that perfect shot.
- If you are a video shooter you might think you need faster cards, but actually video requires less transfer rate than do still photos. The total file sizes are larger yes, but the amount of data being captured with each frame is far less. If you find you’ve been getting dropped frames in your videos than you will benefit from a faster card.