The trend today in higher-end DSLRs is to provide two media slots, but the pro models still rely primarily on CompactFlash cards because of their speed and capacity capabilities. The Canon EOS-1D X has two CompactFlash slots, and the Nikon D4, a CompactFlash slot and a slot for the new XQD cards (more than a year after its introduction, it’s still the only DSLR to use XQD cards). Canon’s EOS 5D Mark III and Nikon’s D800 and D800E each has two card slots: one for CompactFlash and one for SD/SDHC/SDXC (see the sidebar). Sigma’s SD1 Merrill has one card slot, for CompactFlash.
Today, you can get CompactFlash cards in capacities of up to 256 GB, with read/write speeds of up to 160 MB/s. If you shoot RAW still sequences with high-megapixel DSLRs, or full HD or 4K video, you need fast, high-capacity memory cards so you can shoot as fast as the camera was designed to shoot without a bottleneck at the storage end of the pipeline. Conversely, when it’s time to download, you can transfer images from the CF card to your computer’s hard drive in less time (assuming you have a compatibly fast card reader).
A common way to rate memory-card performance is based on the old standard CD transfer rate of 150 KB/s, or 0.15 MB/s. That’s "1X." Thus, 100X is 15 MB/s, 600X is 90 MB/s, and 1000X is 150 MB/sec. Note that these are maximum read rates; the write rate is generally slower—and that’s the rate you’re concerned with in-camera. Newer cards also have a VPG (Video Performance Guarantee) rating—currently, 20 or 65—the minimum MB/s rate at which the card can handle sustained pro video recording without dropping frames.
The Delkin 128 GB CF 1050X UDMA 7 Cinema memory card is UDMA 7-enabled and promises read/write speeds of 160/120 MB/s (1050X). It also offers VPG 20 profiling, with sustained 20 MB/s recording speeds with no dropped frames. Like all UDMA 7 cards, it delivers best performance when used with UDMA-compatible cameras and card readers. Included are a travel-safe case and a lifetime limited warranty. www.delkin.com.
The Hoodman Steel CompactFlash card offers 1000X performance (150 MB/s read, 145 MB/s write), is UDMA 7-compliant and VPG 20-rated, and comes in capacities from 16 GB to 64 GB. Hoodman memory cards are made in the USA and offer a lifetime limited warranty. Although the name includes the word "RAW," they serve all file formats; RAW is the adjective that Hoodman uses to describe their cards’ speed. Hoodman RAW CF cards now use an SSD (solid-state-drive) flash in their construction. SSD flash is among the most reliable available and is said to endure one-half-million life cycles (one life cycle equals a complete fill with data and a complete download). www.hoodmanusa.com.
Kingston’s 32 GB CompactFlash Ultimate 600x card offers write and read speeds of 600x (90 MB/s). Their Ultimate line of CF cards is gaining popularity among pros because of the consistent performance and enhanced reliability. Hailed as a major player in the computer-memory arena, Kingston Technology is one of the world’s largest manufacturers of memory. They produce a variety of memory products for computers and Flash memory for digital cameras, mobile phones, MP3 players and PDAs. Kingston CF cards come with a bonus: Data-recovery software from MediaRECOVER (available via download), so you can restore accidentally deleted image files. www.kingston.com.