Introduction

We recently covered Lexar's entry to the slowly-growing CFexpress Type A portable storage media cards with its GOLD Series and the accompanying card reader that did double duty with SD card support too. I had mentioned at the time how there were not that many devices using CFexpress Type A cards yet with cameras in particular opting to go with the larger CFexpress Type B format. I suppose it's only fitting then that Lexar introduced a new high-performance entry there too, and so here we are!


In case the word "CFexpress" is still new to you, then perhaps this article is more enlightening than one helping you make a purchase decision. CFexpress is the latest standard from the CompactFlash association—the organization behind the famous Compact Flash (CF) memory cards that dominated the prosumer and professional camera market for years as the default memory card format. Indeed, one of my daily driver cameras still uses a CF card, and it's lasted the test of time for durability and consistency. The issue is that those original cards have not kept up with the increased storage bandwidth now available to end users with alternatives, and they are bulkier than what mirrorless cameras prefer. CFexpress is the current solution to this, and it comes in three versions/sizes: Type A, Type B, and Type C. This makes CFexpress analogous to SD cards wherein we have microSD, miniSD, and full-size SD Cards. Today we take a look at Lexar's CFexpress Type B DIAMOND Series, and thanks to the company for providing a test sample to TechPowerUp!

Packaging and Accessories

Lexar sent over not only the CFexpress Type B DIAMOND series memory card itself, but also the matching Type B card reader that launched last year. The card itself is quite new to where the provided sample did not even have retail packaging available at the time of shipping, and I was happy to take up Lexar's offer of a couple of photos when it was ready, shortly before this article was written up. This is fairly standard retail packaging you would see in a brick-and-mortar store and goes well with the DIAMOND series name, owing to the predominantly black color with gray accents design employed. On the front is the Lexar logo and product name, we also find out this is part of the Lexar Professional lineup. A render of the card is seen here too, along with the exact memory size and salient technical features. This continues on the back, in multiple languages, and inside the cardboard packaging will be the plastic clamshell that I have here. It hosts the memory card itself. There may well be some paperwork inside too, but I can't speak about this here.


The card reader, on the other hand, has been selling for a while, thus there was no problem getting a retail unit my way. Here too we see Lexar use a similar design with the company logo and product name, a render of the product in use, and relevant features on the front. There is confirmation of the product being a USB 3.2 Gen2x2 device, to take advantage of those performance benefits, which works well with the faster CFexpress Type B cards too. Opening the box reveals a plastic clamshell with a clear plastic cover over it, and two compartments to hold the items of interest. The larger of the two has the card reader itself, then along the side we find the necessary cable to connect it to your PC. This is a relatively short cable that goes from USB Type-C to Type-A, although I did like that the Type-A section is an adapter in itself that converts the native Type-C connector on the source end too. Props to Lexar for doing this captive adapter implementation and not making me worry about potentially losing it somewhere.

Closer Look and Testing

The Lexar Professional CFexpress Type B card reader was made with the CFexpress Type B GOLD Series cards in mind I imagine, at least based on the color scheme of the packaging there. As mentioned before, it is a USB 3.2 Gen 2x2 interface device, where that Type-C to Type-C (w/Type-A adapter) now makes a lot more sense. It comes in at 98.5 x 65 x 8.2 mm and weighs ~130 g, making it fairly portable for on-the-move content creators. The shape does remind me a lot of a PC mouse though, so I am not sure if this is intentional, given the potential confusion that can arise with this on your desk plugged into a laptop/PC. The card reader employs a plastic composition with a ribbed and dimpled texture for easy grip, and this continues on the bottom with a rubber non-slip base too. There is a large Lexar logo on the top surface with an indicator LED placed towards the sloped front. No glossy surfaces to be seen here, so thankfully this won't be a dust and fingerprint magnet.


The Type-C connection provides for two lanes of up to 10 Gbps transfer speeds for a theoretical max 20 Gbps with a compatible source, which in practice would give you ~2000 Mbps either direction off the USB 3.2 Gen 2x2 ports. This comes in handy paired with a fast CFexpress Type B card that can take advantage of this throughput with many exceeding the 10 Gbps (~1000 Mbps read/write speeds in practice) off the older USB 3.2 Gen 2 standard used on the Lexar CFexpress Type A/SD card reader we saw before. There is no SD card support here though, so this is effectively confined for content creators using cameras that use the popular CFexpress Type B card format. It also has backward compatibility with some XQD cards too so that helps further, but this is clearly a prosumer accessory rather than for someone simply wanting an external storage device.

The Lexar Professional CFexpress Type B DIAMOND series cards use a plastic core that then gets a metal cover plate given a beaded finish on both the front and back. This helps not only with aesthetics but adds to the durability aspect, given the card is rated for shock resistance, tiny plastic nibs on the side add to this feature. On the front is the Lexar Professional branding again, and the storage capacity is placed right below to avoid any confusion. The sticker matches the DIAMOND series moniker well enough, and overall I am happy with the build quality of the card. Lexar does not provide any sort of IP rating here, presumably expecting cameras to instead have weather seals, but the operating temperature range of -10 °C to 70 °C is enough to suggest there shouldn't be an issue with daily operation in testing conditions.


Inserting the CFexpress Type B card into the respective slot in the card reader is simple enough, with an indicator arrow also showing the direction the card goes in for those unfamiliar with it. You then press in till it clicks into the slot itself, before simply connecting the card reader to a compatible USB 3.2 Gen 2x2 slot on your PC using the provided cable. My test system unfortunately does not have one available and thus I had to make do with a USB 3.2 Gen 2 port itself following which the indicator LED lights up in a static blue for power and then flashing thereafter during write/read activity. You will need the newer Gen 2x2 port to make the most of the card and the card reader for data transfer back and forth at least, and the other end of the chain involves whatever speeds your camera is capable of writing on to the card. The relatively shorter cable makes it clear the card reader is meant to be taken along with you and used on a laptop primarily. You get native support with Windows XP and newer, with the card reader also being backwards compatible back to USB 2.0 as needed. It also supports macOS 10.8 and newer for those who prefer Apple.


I first used the card in an actual camera and confirmed it works great for RAW images as well as 4K/8K video footage, without any buffer issues—the camera itself was the bottleneck here in writing to the card. The issue here wasn't performance as much as storage capacity itself. I got the 128 GB version of the card and it maxes out at 256 GB, which isn't a lot these days if you are shooting RAW 8K videos in particular. This is all the more striking when you realize Lexar's own older CFexpress Type B GOLD Series comes in 64-512 GB versions while being rated for only slightly slower read/write speeds. On the plus side, these cards will survive basically forever. My older CF card has been going strong for over a decade now and the limited lifetime warranty provided by Lexar indicates no difference here either.

Next I had to see how the card and card reader combination worked together, seen above are some quick synthetic read and write speed tests. Keep in mind that I had no USB 3.2 Gen2x2 port available to maximize the card reader's potential and yet the combination worked better on the same system on a USB 3.2 Gen 2 port compared even to the previously tested Lexar CFexpress Type A GOLD Series card, on its matching reader. The CFexpress Type B DIAMOND series cards are clearly better performing even when held back by the source and I have no reason to doubt it'll hit the rated numbers either. What is also good to see is the card ran way cooler compared to the smaller and slower Type A card—going from 37 °C to a max of 48 °C in a 20 °C ambient—and sustained writing, as is typical with video recording did not result in thermal throttling either.

There's a lot to like about the Lexar offering in the CFexpress Type B market but the limited storage options on this DIAMOND Series don't help, when compared to the existing solutions. Then we get to pricing where this card costs $199.99 (128 GB) or $329.99 (256 GB) from the likes of Amazon, Adorama or B&H along with the card reader for an additional $70. Lexar's own CFexpress Type B GOLD Series cards cost $140/$270/$480 for the 128/256/512 GB offerings and they also come with a discounted card reader combo to further sweeten the deal. The competition in the CFexpress Type B media card market is a lot more than on the Type A side and I can't help but think Lexar needs to do more here, even though the cards themselves are excellent performers.