Gadget Bag: High-Speed CompactFlash Cards

To take advantage of the latest high-res video HDSLRs, you’ll feel the need for speed and capacity, and contrary to what you may have heard, the death of CF has been greatly overstated
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Readers of Outdoor Photographer are attracted to DSLRs with large, high-res sensors. We want to record details, shoot wildlife action at high speed and have the ability to crop and enlarge the images to make big prints. Today, we have 36-megapixel DSLRs, and DSLRs and SLTs that can shoot 16- to 24-megapixel RAW files at 12 fps. So the need for fast, high-capacity memory cards has never been greater. And the interest in time-lapse shooting as well as full HD video also requires fast, high-capacity cards. Fortunately, they're available—and for much less money per MB than a decade ago.


You say you shoot landscapes, so you don't need to shoot RAW files at 12 fps? Well, you probably shoot a high-megapixel camera to get maximum detail. Those big RAW files require fast, high-capacity memory cards, and many landscape photographers do HDR images or stitched panoramas, or bracket exposures. These require making a number of shots, preferably quickly so the light doesn't change partway through the sequence. Here, again, a quick memory card is a boon.

Digital cameras have buffers, memory where image files are stored while they're being written to the memory card. Higher-end cameras have bigger buffers and, thus, can shoot more images in a burst before filling the buffer. Once the buffer is full, you have to wait until files are written to the card before you can continue shooting.


Fast memory cards (assuming your camera can take advantage of that speed; most newer ones can) mean writing images to the card goes faster, and you can shoot more quickly. Faster cards (again, assuming your card reader and computer can handle the speed) also mean the images transfer to your computer more quickly.

The most common memory cards for cameras are CompactFlash and Secure Digital (SD). Currently, the fastest CompactFlash cards are somewhat faster than the fastest SDHC and SDXC cards. (XQD cards are faster still, but so far only the Nikon D4 DSLR uses them; the D4 also uses CompactFlash cards.)


CompactFlash Background
At 43x46mm, CompactFlash cards are somewhat larger than other formats like SD. But that also means they're not so easy to lose in the field. There are two types: I (3.3mm thick) and II (5mm thick). All cameras that accept CompactFlash can use Type I cards, but not all can use the thicker Type II. But the newer, faster, higher-capacity cards are all Type I, so that's not a problem. Current CF cards are available in capacities from 2 GB to 256 GB, with speeds of up to 1000X (150 MB/s read, 80 MB/s write). Things to look for are "UDMA 7" and "VPG-20." UDMA stands for Ultra Direct Memory Access, and using UDMA 7 CF cards in UDMA 7-compliant cameras results in the fastest transfer rates—up to 167 MB/s versus 133 MB/s for the earlier UDMA 6. VGA stands for Video Performance Guidance, and VPG-20 means the card can support sustained speeds of up to 20 MB/s for smooth 1080 video with no dropped frames, even with under- or overcranking (high-speed and slow-motion video).

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A Selection Of CompactFlash Manufacturers
CompactFlash cards are available from a number of manufacturers, including Delkin, Hoodman, Kingston, Lexar, SanDisk and Transcend (many of whom also make SD cards). Note that to enjoy the speed benefits of the latest fast cards, your camera must be compatible with their standards—put a fast card in an older, slow camera, and the card won't accept data faster than the camera can deliver it. Check your camera manual to see what cards it can use.

Delkin's ( fastest CF cards are the 1000X UDMA 7 line, with reading up to 150 MB/s and writing up to 80 MB/s, and capacities from 16 GB to 128 GB (a 256 GB card is due soon). The cards support VPG profiling and carry a lifetime warranty.

What exactly do those "X ratings" on memory cards mean? Well, one "X" is the old standard CD transfer rate of 150 KB/s, or 0.15 MB/s. Thus, 100X is 15 MB/s, 200X is 30 MB/s, 400X is 60 MB/s, 600X is 90 MB/s and 1000X is 150 MB/s. Note that these are maximum read rates; often, the maximum write rate is somewhat slower. And keep in mind that system speed depends on both the camera and the card. Putting a slow card in a fast camera will slow things down, but putting a fast card in a slow camera won't speed things up. For best burst and video performance, use the fastest card your camera can handle; see the camera's instruction manual.

Hoodman ( offers the Steel Professional CompactFlash Card 1000X in capacities from 16 GB to 64 GB, with read speeds of up to 150 MB/s and write speeds of up to 145 MB/s. The UDMA 7- and VPG-20-compliant cards come with a lifetime warranty.

Kingston's ( top CF card is the Ultimate 600X in 16 GB and 32 GB capa­cities. It can read and write up to 90 MB/s, and comes with a lifetime warranty.

Lexar's ( fastest CF card is the Professional 1000X UDMA 7, which can read up to 150 MB/s and write up to 145 MB/s. It's available in capacities from 16 GB to 128 GB, supports VPG-20 and comes with a limited lifetime warranty.

SanDisk ( offers the Extreme Pro UDMA 7 CF cards in capacities from 16 GB to 128 GB, with the 128 GB capable of speeds of up to 100 MB/s, the others to 90 MB/s. Extreme Pro cards are VPG-20-compliant and come with a lifetime limited warranty.

Transcend ( offers a 64 GB 600X UDMA 7 CompactFlash card that can read and write up to 90 MB/s, is VPG-20-compliant and carries a limited lifetime warranty.

Approximate Card Capacities
Choosing the best capacity is a personal decision that you should base upon how you shoot. If you're shooting full HD video, the highest capacity that you can afford is a necessity. Many time-lapse shooters prefer to shoot high-res JPEGs even though the images will get resized for playback. (Even if you want to render your time-lapse as a massive 4K project, the individual frames will still get resized smaller.) The reason some time-lapse shooters capture in high-res is to give themselves options down the road and to future-proof the project as much as possible. The chart below will give you a rough idea of how many images or how much HD video fits on the various card sizes. We say it's a rough idea because images compress differently and final file sizes can vary.
16 GB Card 32 GB Card 64 GB Card 128 GB Card 256 GB Card
12 MP JPEG 2000 4000 8000 16,000 32,000
16 MP JPEG 1600 3200 6400 12,800 25,600
18 MP JPEG 2400 4800 9600 19,200 38,400
24 MP JPEG 800 1600 3200 6400 12,800
12 MP RAW 800 1600 3200 6400 12,800
16 MP RAW 600 1200 2400 4800 9600
18 MP RAW 560 1020 2040 4080 9160
24 MP RAW 400 800 1600 3200 6400
1080/60P AVCHD* 1:15 2:30 5:00 10:00 20:00
1080/30P MP4* 2:45 5:30 11:00 22:00 44:00
Note: JPEG figures are for "highest-quality" JPEG settings; all figures are "ballpark" figures. The actual number of shots per card depends on the individual camera, the specific RAW or JPEG setting chosen and the scene content. For video, actual recording time per card depends on video format, compression and scene content. The figures for 18 MP JPEGs aren't consistent with the figures for 12 MP, 16 MP and 24 MP JPEGs because the manufacturer of the 18 MP cameras referenced uses different compression than the manufacturers of the 12 MP, 16 MP and 24 MP cameras. We compiled these figures from the published specifications provided by a number of manufacturers in their owner's manuals. *Hours:Minutes


    Hello there!
    I am shooting HD video with 5D mark ii, 5D mark iii and 7D cameras, and something confuses me here on page 3 of ‘CF cards’ article –
    This table of different cards and video lenghts…
    It says that 16 GB card can handle 1:15 or 2:45 of 1080 video…
    All my UDMA 6, 16GB cards can shoot 40min videos (5d mk iii can strech it to 50 with “lower” quality codec….
    I wonder if I didn’t understand this table well or was it maybe mistaken for SD video lenghts (which is only thing I can imagine could last that long on these card capacities)

    Hello there! You told us to see the camera`s instruction manual to find out what speed of card it could handle. If only things was that simple! I got a used Canon 50D, upgrad it to firmware 1.0.9, and start looking for cards for it. The instruction manual said nothing about what cards to use, and I have had lot of trouble with several CF-Cards from Transcend. Likewise Cards from Kingston (Ultimate 600x) on the other hand has worked out nicely. A frustrated situation! Cheers!

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