What you need to know before buying a memory card for your camera.
Chris Gooley | AUSTRALIA
1. Types of Memory Cards
Compact Flash (CF)
Compact Flash Type I: 3.5mm thick and still used today. Newer cards and cameras use the faster UDMA interface for higher transfer speeds. Often used in DSLR cameras.
Compact Flash Type II: 5mm thick and no longer supported by most modern DSLRs.
CFast2.0: is based on the Serial ATA interface, not a Parallel ATA interface like the original CompactFlash cards. They support a higher maximum transfer rate than current CompactFlash cards. CFast cards also use a different data connection and require adapters to use with standard SATA drives.
XQD Cards: designed for HD camcorders and high-resolution digital photo cameras. It offers potential write speeds of up to 1Gbit/s and read speeds up to 4 Gbits/s. Also it offers storage capacity of over 2TiB.
Secure Digital (SD)
SD cards are the oldest and least powerful SD card type, with a maximum capacity of 2GB. You can still use SD cards in modern digital cameras, but their low capacity limits their usefulness.
As a result, standard SD cards are rarely seen now – SDHC is the new norm.
SDHC cards are a faster, higher-capacity replacement for the SD format. Card sizes go up to 32GB, with card speeds up to Class 10 and UHS-I.
You can only use SDHC cards in cameras that support them – and most current DSLRs support SDHC.
SDXC cards offer higher capacities even than SDHC, starting at 64GB and going up to a theoretical maximum of 2TB. SDXC cards typically come with a UHS-1 speed rating.
Micro SD come in all of the SD family, SD/SDHC/SDXC and are used in small devices such as the GoPro & mobile phones.
2. Storage Capacity
For High End Digital Camera and HD recording
- – More photos can be stores when shooting with less MP. Conversely less photos can be stored when shooting with higher MP.
- – More minutes can be stored when shooting in lower resolution. And less minutes for shooting in higher resolutions (see tables below for higher resolution storage capacities).
For Black Magic Pocket Cinema Camera
- – When using Apple ProRes 422 (HQ) you need memory card write speeds of 27.5 MB/s. Recording in CinemaDNG RAW requires memory card write speeds of 60MB/s
For when using Magic Lantern firmware (RAW filming)
- – When using Magic lantern with your Canon EOS DSLR you require Memory Cards with write speeds of 76MB/s or more.
3. Read and Write Speeds
Read Speeds are how fast you can transfer information written on memory cards to other devices such as computers, external hard drives, TV and other viewing devices.
Read speeds are often faster than write speeds and are really only important when downloading a lot of large photos or video files from your card. This becomes important when shooting in the field and you need to back up cards quickly so not to miss much of the action.
However, in order to take full advantage of the latest high-speed cards, you’ll need to use a USB 3.0-enabled computer and card reader.
It is industry standard to advertise the read speeds on the card, which is a little misleading, as they are often faster than the write speeds.
Write speeds are how fast the information you are shooting can be recorded onto the memory card.
This is important when shooting rapid bursts of images, HD video or when shooting in high-resolution. Basically this is the key factor that determines whether the card will allow you to take full advantage of your cameras shooting capabilities and must be carefully considered when choosing a memory card.
Camera Features that require fast write speeds
Rapid burst shooting requires your camera to save images faster than it can write them to the memory card. Therefore the cameras internally memory, known as its buffer, temporarily stores the images while waiting to write them to your card. The higher write speed of your memory card, the less likely your buffer will fill up and therefore you won’t have to wait for images to write before you can continue shooting. A fast write speed, therefore, allows you to shoot more images in a shorter period of time while shooting in rapid burst mode and means you can still use the highest resolution RAW settings.
HD Filming over 720p will require your card to have a fast enough minimum sustained write speeds or else you will drop frames or your camera will simply stop recording.
SD/SDHC/SDXC memory cards have Class ratings (Class 2, 4, 6, 10, UHS-I, UHS-II) for filming full HD 1080 videos you require a Class 10 to ensure good results.
For CF (Compact Flash) cards there is no standard to describe minimum sustained speed. As a reference the canon 7d records at 7MB/s when filming full HD 1080 video. Meaning any of the newer 20MB/s (133X) CF cards should be able to handle HD on a 7d.
High-Resolution Filming requires much faster write speeds than for HD filming. The Black Magic Pocket Cinema Camera when filming in ProRes 422 HQ records at roughly 30MB/s. In CinemaDNG RAW it records at roughly 60MB/s. Therefore you will need Gobe’s SDXC UHS-1 104MB/s card when using the Black Magic in ProRess and even faster cards when wanting to shoot in RAW.
For Magic Lantern filming in RAW, you require write speeds of over 76MB/s. A minimum UDMA 7 class rating CF card and at least 64GB capacity to expect anything other than very brief shoots.
Cards with these capabilities are often very expensive and you will need more than one card when shooting with these size files.
4. Industry Classifications
SD Memory Cards are categorized into classes as per the table below:
For example, Class 6 means 6 MB per second minimum speed, this is the slowest of the Read or Write Speeds.
Most newer SD cards will show their maximum MB/s speeds either on the card itself or in the product description. Remember that the maximum Read Speed is usually displayed not the maximum write speed. Determining the maximum write speed is the best way to distinguish which SD card is the fastest while shooting.
Compact Flash Memory Cards have two main modes of classification, the X rating and the UDMA rating.
X ratings are shown in the table below:
These again are the Read Speeds of the card, Write Speeds will often be slower though not always – be diligent and check this in the product specifications.
Remember anything above 200x rating will need a USB 3.0 port to see utilize it’s full speed.
Most newer CF cards will show their maximum MB/s speeds either on the card itself or in the product description, as this is a more precise indication than the X rating. Determining the maximum write speed is the best way to distinguish which CF card is the fastest while shooting.
5. Memory Card Compatibility
When searching for a Memory Card for your device you will need either an SD or Micro SD (Secure Digital) or CF (Compact Flash) card and some top end DSLR’s have a slot for both. The exceptions are older Olympus and fujifilmdigitial camera which use xD cards. Also some Sony devices which only accept Sony Memory Cards.
The best way to know what memory card you require is to look up manual for your device or search your specific device on the Internet for answers.
SD: these are the oldest cards and they will work in any camera with an SD card slot, except the high end devices which require greater capabilities.
SDHC: newer cards but only work in SDHC-compatible. They are not backwards compatible.
SDXC cards will only comply with cameras that support them which entails cameras made after 2010.
Micro SD’s: are generally used in smaller devices, for example GoPro’s, Mobile Phone’s, small GPS devices, Portable Media Players, etc.
Many Micro SD cards have a standard SD adapter, so that people can use them in devices that take standard SD.
You will need a Compact Flash Type I card for your new DSLR. Most of the newer CF cards use the faster UDMA interface for higher transfer speeds.
Compact Flash Type II: no longer made or supported by modern DSLR’s.
UDMA-7: Compact Flash cards are backwards compatible with older cameras they won’t achieve their maximum speeds.
CFast 2.0: are not compatible with CompactFlash devices.
XQD Cards: designed for exceptionally high-resolution devices and not backwards compatible with either the CFast cards or the CompactFlash cards.
Card Compatibility for Magic Lantern
For Magic Lantern RAW recording onto your Canon you need a Compact Flash UDMA 7 card with a write speed of at least 100MB/s to ensure no dropped frames. You will need a 1000x (100MB/s) UDMA 7 CF card and a minimum 64GB capacity to anything except very brief shoots.
Card Compatibility for Black Magic Pocket Cinema Camera
The Black Magic Pocket Cinema Camera supports SDXC cards only. When filming in ProRes 422 HQ it records at a minimum of 30MB/s. In CinemaDNG RAW it records at a minimum of 60MB/s.
Some cards will only perform in ProRes 422 HQ mode and a lot of cards will not be recognized at all by this camera. For exampleGobe’s SDXC UHS-1 card will work well in all ProRes modes though do not support filming in RAW.
6. Card Features – What you pay for
Beside storage capacity and speed there are other factors worth considering that determine the value of a memory card. The biggest concern with memory cards is card reliability. Features that make your card reliable include:
Error Correction Code (ECC): That will detects and repairs sector errors before they become a problem, so your data is safe and retrievable.
Extreme Temperature Resistance: The temperature resistance range is a good indicator of card reliability. The better cards will offer a range of -25C to 85C.
Card Protection: As well as extreme temperature resistance top end cards should also be X ray-proof, Waterproof, Magnet-proof & Shock-proof.
Warranty: You should expect a lifetime warranty with any of the leading cards.
Manufacture Support: Buying from a company that sells direct to the public and offers excellent customer service will usually give you peace of mind when it comes to ensuring you are purchasing a quality product.
Things to be wary off when purchasing Memory Cards
Fake or Poor Quality: It is important to choice a memory card brand that you can trust. Currently there are many cheap alternatives on the market that don’t provide quality products. If losing your precious memories or work related data is a major concern make sure you purchase your card from a company with a reliable brand and also someone you can talk to about your purchase. And remember that fake duplicates of top brands are a problem when buying on platforms such as Ebay and Amazon.
Retail Mark-ups: Another thing to remember is that you will be paying for a whole distributing chain when purchasing from most of the biggest brands. So finding a company that brings you the product direct from the factory can save you a lot of money without losing quality. Also, shopping online will save you from paying for passed on shop front overheads.
Be informed: Last thing to be wary of is that Read Speeds are advertised on the card in lieu of the Write Speeds. This is a little misleading, as they are often faster than the write speeds and arguably less important. Make sure you check the Write Speed in the product specifications when comparing Memory Cards.
7. Card Readers
Card Readers have a slot for your memory card and use USB interface to transfer data straight from your memory card. They can also allow you to write onto your memory card through the USB interface, effectively acting as a pen drive if desired.
The great advantage is you don’t need to carry USB cables for each of your devices. You can get Card Readers for all different types of memory cards or a Card Reader with multiple slots to fit all many types of Memory Cards.
The newer card readers should have USB 3.0 interface to ensure you take advantage of the full read speed on your memory card. Most of the newer 3.0 USB interfaces will be backwards compatible to support USB 1.1 & 2.0 as well.
Remember that your memory card read speed advertised relates to the use of USB 3.0 interface.
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