The need for high-speed, high-capacity memory cards

If you’ve purchased a new camera recently, you may have also been required to buy a new memory card to use in it – probably one of the two CFexpress card formats. There are reasons for this; the main one being the shift from stills-only photography to a ‘hybrid’ model that combines stills and video shooting.

Thanks to developments like stacking the electronics behind the image sensor and boosting data offloading speeds, the sensors and processors in the latest cameras are much faster than before. The latest cameras also offer faster, more accurate focusing, higher frame rates and blackout-free viewfinders.

Fast, high-capacity memory cards let you take advantage of all these improvements. However, they come at a cost since CFexpress cards cost a lot more than SD cards with equivalent capacities. Even low-capacity 64GB cards will set you back almost AU$200, which is roughly ten times the price of a 64GB SD card, so you should balance your needs for speed against how much you’re prepared to pay to support faster data recording.

Photographers who shoot mainly (or entirely) stills may not see the need for speed – unless they shoot a lot of high-speed action requiring fast burst speeds and high buffer capacities. That said, fast capture speed will be very useful for serious birders and most sports photographers, particularly those who shoot action sports like basketball, netball, mountain biking and skateboarding.

Fast, high-capacity CFexpress cards are required for cameras that record 6K and/or 8K video because of the large quantity of data this entails. (Source: Lexar.)

If you’re involved in video production, you’ll need fast, high-capacity cards to handle the amount of image data produced with 6K and 8K recordings to avoid bottlenecks in your workflow. Therefore, you need to pay attention to the memory card(s) your cameras use and understand the differences between the different types.

Depending on where your interests lie, choosing the right memory card for you can help you get the most of your camera. A good starting point is to know which memory card(s) your current camera uses.

The table below shows the options available in enthusiast and professional level interchangeable-lens cameras at the time of publication.

Brand	Models	Type A	Type B	SD card slot
Canon	EOS R1, EOS R5 II, EOS R5, EOS R3, EOS R5 C		2x CFexpress 1x CFexpress 1x CFexpress	1x SD UHS-II 1x SD UHS-II
Fujifilm	GFX 100 II		1x CFexpress	1x SD UHS-II
Hasselblad	X2D 100c		1x CFexpress
Leica	SL3, SL3-S		1x CFexpress	1x SD UHS-II
Nikon	Z6 III, Z6 II, Z6, Z7 Z9 Z8		*1x CFexpress 1x CFexpress 1x CFexpress	1x SD UHS-II 1x SD UHS-II 1x SD UHS-II
Panasonic	DC-S1 II, DC-S1R II		1x CFexpress	1x SD UHS-II
Sony	α1, α1 II α7R V, α7 IV FX2, FX3 α9 III	1x CFexpress 1x CFexpress 1x CFexpress		1x SD UHS-II 1x SD UHS-II 1x SD UHS-II 2x SD UHS-II**

* Initially supported XQD cards when released in August 2018. A subsequent firmware update enabled support for CFexpress Type B.

As you can see from the above table, different camera manufacturers have adopted different CFexpress formats. While all CFexpress are based on a standard developed by the CompactFlash Association, Sony was the first to release CFexpress Type A cards and remains a prominent manufacturer.

One reason Sony adopted Type A is because it has a similar form factor to SD. This has enabled Sony to make cameras with slightly smaller, lighter bodies and offer the convenience of media slots that can accept both CFexpress and SD cards.

Sony’s professional cameras use Type A CFexpress cards, which have a similar form factor to SD cards, allowing both cards to be used. However, for high-resolution video or long bursts of high-resolution stills, only CFexpress can meet the demands of the data workflow. (Source: Sony.)

The other manufacturers have so far chosen the Type B format, largely because these cards are roughly twice as fast as Type A cards. They are also available in a wider range of storage capacities and are better at handling high-speed data writing because they have more pathways (PCIe lanes) for transferring data. The table below shows the main differences between the two card types.

Feature	Type A	Type B
Size (mm)	20 x 28 x 2.8	29.97 x 38.5 x 3.7
PCIe Lanes	1	2 or 4
Max Read Speed (MB/s)	Up to 1000	Up to 1700
Max Write Speed (MB/s)	Up to 800	Up to 1500

Type B CFexpress are roughly twice as fast as Type A cards, which is why most manufacturers have chosen this format. Most manufacturers pair a CFexpress slot with a regular SD slot, as shown in this illustration. (Source: Nikon.)

Why cameras need fast cards
Faster data transfer speeds are the main reason for camera manufacturers adopting the CFexpress format, driven mainly by demand for more cameras to be capable of recording high-resolution, high frame-rate movies. However, it’s also important to have high-capacity cards because high-resolution photos and videos take up a lot of storage space.

The table below shows typical frame sizes and resolutions plus file sizes for one minute of 30 fps high-resolution video to give you some idea of how much storage capacity is required for the main high-resolution video formats.

	Frame size (pixels)	Frame resolution (megapixels)	File size for 1 minute of recording
8K 17:9	8128 x 4288	34.85	2,091 MB
8K 16:9	7680 x 4320	33.2	1,991 MB
6K	6144 x 3160	19.4	1,165 MB
5.8K 17:9	5760 x 4030	23.2	1,393 MB
C4K	4096 x 2160	8.85	531 MB
4K	3840 x 2160	8.01	485 MB

Fast cards also provide better support for burst shooting involving large images, particularly raw files, which record all the image data. Most cameras that use CFexpress cards have large buffer capacities for burst storage, with the smallest raw file capacities typically being around 70-80 files and the largest around 1000 files.

Currently, CFexpress cards offer a range of storage capacities, from 32GB up to 4TB, with the most popular capacities being 256GB, 480GB, and 512GB. Currently, the highest storage capacity for CFexpress Type A cards is 1.92TB, whereas Type B cards are available in capacities up to 4TB.   The table below shows typical storage capacities for image and video files.

Capacity	Approx. JPEG photos at 24MP	Approx.  24MP – uncompressed RAW files	Approx. minutes of 4K video (30 Mbps)	Approx. minutes of 8K video (60 Mbps)
1TB	428,785	12,800	2,083	1,042
512GB	214,286	6,400	1,042	521
256GB	107,143	3,200	521	260
128GB	53,571	1,600	260	130
64GB	26,786	800	130	65
32GB	13,393	400	65	32
16GB	6,696	200	32	16
8GB	3,348	100	16	8

CFexpress Type B cards offer higher storage capacities, including 1TB, 2TB and 4TB for high-volume users. (Source: Angelbird.)

Worth the investment?
One reason CFexpress cards cost more than SD cards with equivalent capacities is because newer, faster technology involves higher production costs and more specialised components.  If you really need the card speed and/or both speed and capacity for fast burst shooting, it’s usually worth the investment. But if you only shoot stills and seldom record fast bursts of uncompressed raw files, a CFexpress card could seem like over-kill.

One additional benefit to take into account is the ability to extract high-resolution image frames from video recordings. A 6K video frame has a resolution of approximately 6144 x 3160 pixels, which equates to approximately 19 megapixels. Similarly, an 8K video frame is approximately 680 x 4320 pixels, which is just over 33 megapixels per frame.

Cameras that offer these high resolutions usually support frame rates of around 30 fps, which is faster than most cameras’ still frame burst rates. An increasing number of these cameras are also allowing users to select different aspect ratios for their high-resolution video recordings, so these features combined can make them advantageous for sports and action photographers.

Fast, high-capacity CFexpress cards can make a valuable contribution to workflow efficiency for photographers on the move. (Source: Lexar.)

If you’ve purchased a Sony camera you should be safe to use appropriate SD cards in the CFexpress Type A slot. They won’t be as fast as the CFexpress but they may be fast enough for your requirements

However, if you’ve recently invested in a sophisticated camera from one of the other camera manufacturers that support Type B CFexpress you’ll need to weigh up whether it’s worth buying the more expensive card for the convenience of recording files to two separate cards. Dual media slots offer several key advantages in the form of data backup, increased storage capacity, flexible file management and workflow efficiency. These features are particularly valuable for professional photographers and videographers but also worthwhile for many serious photographers.

Cameras with dual slots can be configured to store different file types on separate cards, allowing you to separate JPEG and raw files, stills and videos and video proxy files from actual recordings.  This allows more efficient file management and quicker access to the desired file types.

Article by Margaret Brown

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