CFExpress Type B memory cards, once considered an exotic choice, have become the gold standard in recent years. Although they are still not as common as widely adopted SD cards, many high-end cameras now feature at least one CFExpress slot, including those from Canon, Nikon, Leica, Fujifilm, and Hasselblad. The reason is simple: these cards provide excellent speeds for the demanding professional photographer.
However, it would be difficult to call CFExpress Type B cards “affordable”, especially the fastest ones. This is one of the compromises of such advanced memory cards, and there is no way to avoid it. or is there?
Actually, the answer is yes. I thought it was an incredible thing to see – namely, a tech-savvy friend of mine who uses cheap do-it-yourself CFexpress Type B cards! Not only that, they also graciously allowed me to dissect it, take pictures of its insides, test its performance, and hopefully return it “alive.” Now I can say that I managed to accomplish everything including the last point.
For a variety of reasons, including no warranty and less durable cards, I don’t recommend you do thisBut I leave you with the following information out of sheer curiosity and fascination with the possibility of such a thing. (And should you ignore my recommendation and try it yourself, you now know how.)
Material
At the heart of this DIY memory card is an NVMe M.2 2230 SSD. Yes, the same type of drive you might find in your laptop. Although this form factor is available in capacities up to 2TB, it’s best to follow the adapter manufacturer’s recommendations when choosing your SSD (more on that later). For this purpose, my friend used the Western Digital WD SN740 2TB, which can currently be found around $150 on ebay.
Then, you will need the CFexpress Type B to 2230 NVMe M.2 SSD Adapter. It’s basically an aluminum or copper casing shaped like a CFexpress memory card. Material selection can affect heat dissipation. If you’re shooting video or doing frequent burst shooting, a copper adapter may be a better choice, as the thermal conductivity of copper is about 60% higher than that of aluminum. Cost of the aluminum adapter I tested $14.50While the copper version is actually a bit cheaper $11.45Both come with six screws to hold the adapter together, plus a small screwdriver. The manufacturer’s website also provides a list of compatible SSDs for your camera model.
To improve heat transfer between the SSD and the metal case of the adapter, a thin layer of thermal grease is recommended. This is the same type of grease that is used to improve heat dissipation between a computer processor and its heatsink. You will only need a very small amount, so a $10 tube Will stay with you for a long time. To apply it, I used a makeshift spatula – a trimmed wooden ice cream stick worked perfectly.
assembly instructions
Gather all the components you need and lay them out on an antistatic surface. I used the clean wooden surface of my workbench.
1. First, dry fit all the parts together without screws or thermal grease to make sure everything is properly aligned.
2. Next, repeat the process, but this time apply a modest amount of thermal grease. Use your spatula to spread a thin, even layer like butter on a slice of bread on the inside of the adapter housing. Be careful not to overdo it – excess paste can seep into the connectors during assembly, which you definitely want to avoid.
3. Now you can screw both parts of the metal housing together. Start by tightening one screw on each side, then add the remaining screws and make sure everything is securely fastened.
At this point, you should have a ready-made CFExpress Type B memory card on hand. Depending on the capacity of the SSD, you can label it accordingly (256GB to 2TB sticker with aluminum adapter included). I have to admit, the light purple anodized finish of the CNC-machined aluminum case looked quite sleek.
Still, I was a little nervous when I inserted the card into my Nikon Z9 and started formatting. Luckily, the camera didn’t start smoking and my test image came out just fine.
speed test
I tested the DIY memory card using the same methods described in our article Fastest Memory Card for NikonOn paper, the Western Digital WD SN740 2TB SSD boasts impressive speed specs (read: 5150 MB/s, write: 4850 MB/s), which sets high expectations. After all, even the fastest memory cards in today’s cameras can’t even come close to half this speed!
Unfortunately, much of that speed was lost somewhere in the adapter circuitry, resulting in somewhat disappointing performance. During continuous shooting of 14-bit lossless compressed RAW files, the card managed an average write speed of 347 MB/s, capturing 6.3 frames per second for one minute. This is on par with the speeds of the XQD cards tested and slightly better than the fastest SD cards, which max out at about 4.6 fps. But a traditional CFexpress card will almost certainly be faster.
This speed really isn’t fast enough for 8K video, especially 8K RAW. (For that purpose, you’ll want a card at least twice as fast.) I’ll note that the manufacturer of the adapter, JEYI, says that if we put the faster WD SN520 SSD in the adapter, the Nikon Z9 should be capable of 8K/8K resolution. Record video up to 60p RAW. But I haven’t tested this claim myself and I’m a little skeptical, especially for longer footage where overheating could become a problem.
Potential Use Cases
The mere phrase “DIY CFexpress card” probably strikes fear into most photographers, perhaps with good reason. At least you’re not creating a memory card entirely – instead, you’re simply using the laptop’s SSD in a CFexpress-sized container. But is there any reason to ignore my warning and try it yourself?
Probably the biggest argument for embarking on this adventure is the price. For my 2TB DIY card, I would have to pay about $170. Meanwhile the cheapest 2TB CFexpress card typically sells for $346 (After heavy discount).
However, price is only part of the story. Over time, the cost fades from memory, leaving only the card’s performance, reliability, and practicality. So, does the DIY card hold up?
Speed is a serious limitation with this card. So is durability too. Industrially manufactured memory cards are made to withstand extreme conditions, including a trip through the washing machine. While the DIY card’s precisely machined metal casing offers some protection, it certainly isn’t waterproof. Moisture can seep through the connector area, which lacks any sealing. Although this may not be a problem in dry climates, I would be careful in high humidity environments like tropical rainforests. And a memory card that you can’t bring with you everywhere is not a good card.
Finally, compatibility may be an issue. According to the manufacturer’s compatibility chart, some cameras prefer certain SSD models over others. Although this may not matter if you only use one camera, it is still a concern for many photographers.
So, would I recommend making a DIY CFexpress card? Well, I would not use this card for photo and video capture under any circumstances. But there is one situation where making one of these cards might be appropriate: backing up photos in the field.
Many cameras allow you to backup photos from slot 1 to slot 2 internally. This is very convenient and allows you to travel without a laptop, or simply back up your photos more often in the field. But if your camera has two CFExpress slots, this process can be expensive, as there are no cheap, high-capacity CFExpress cards available.
I still wouldn’t put my only copy of a photo on one of these DIY cards. But for backup in the field without any cables or other necessary equipment, I would definitely consider it. Be sure to put the cards in a weatherproof case when you’re finished.
That said, there’s no need for this unless your camera has dual CFexpress card slots. If your camera has dual SD cards, or a CFexpress + an SD, it will be cheaper and easier to get a higher capacity SD card. Therefore, it only applies to a few cameras on the market today, such as the Nikon Z9, Canon EOS R1, and Nikon D6. (Not to mention that if you have enough money to buy any of these cameras, you probably also have enough money to buy a proper memory card instead.)
The DIY memory card I tested is cheap, but it does not stand out for its speed parameters or durability. I don’t recommend it for any critical applications other than potentially making backups while traveling (and even then, only if your camera has dual CFExpress slots). In short, it’s not very practical or useful for most photographers. But maybe now you, like me, have learned something new about CFexpress!