CFExpress Cards Speed Tests

[Kayaker72]

Let me start off by stating, I do not expect that I will often use top end specs of an R3 or R1 camera. Heck, for the R5, I do use the 20 fps, but I do not fill the buffer, it is for a few second bursts.

That said, some speculation I have seen really has me wondering about the R1. The speculation is high FPS and high MPs. But, that equates to high data throughput. So, I ran some numbers starting with theoretical max write speeds of CFExpress cards (~1400 MB/sec of actual cards and 2 GB/sec for Type B). But, then I got to thinking no card ever performs as well as rated. So, I played with Bryan's data of # pictures before hitting the buffer on the R5. Based on the numbers, I get the R5 buffer being 4-6 GB, but the write speed of the ProGrade Cobalt card he used only being ~500 MB/sec, or 1/3 of its rated 1500 MB/sec.

This made me look online, and I did find this article. First, the difference among cards is impressive, even different capacities (Sandisk, looking at you). They published time to clear the buffer on the R5, not MB/sec, but they estimate the buffer to be 2 GB and 4-8 seconds to clear gives the write times to the cards would be 250-500 MB/sec. Way off of the spec. (BTW, they also got very different results to Bryan in terms of pictures to fill buffer, so, something is inconsistent between these tests).

Their write speeds using a card reader were 450-800 MB/sec. Again, way off the spec, but at least getting closer.

So, I have always known cards perform at less than their max spec. However, usually they are 50-75% of that spec, not 15 to 33%.

CFExpress, still better than SD UHS II (which are typically ~180-200 MB/sec), but they are not functioning nearly as well as is being widely assumed.

I assume with the R1, Canon will want to have something similar to the 1DXIII where it doesn't hit a buffer (rated at >1000 RAW images). But the 1DXIII is only moving ~600 MB/sec with its 20 MB sensor to do that. Canon can not go much higher in MPs before they run into limitations of the actual write speeds to CFExpress cards. Which means one element we may be waiting on a high MP/high frame rate camera is improvements to CFExpress cards. Specifically, looks like current CFexpress Type B cards are PCIe 3.0 x2 lanes and is currently maxed out at 2 GB/sec. Type C (similar in size to old CF cards) with PCIe 3.0 x4 lanes can do up to 4 GB/sec eventually and I saw reference to PCIe 4.0 is eventually coming. But, that also means, if you want the top end specs, we'll likely be looking at new cards.

[neuroanatomist]

Thanks for posting, Brant! I have typically used SanDisk cards but would probably have gone with the 128 GB capacity for the R3. I suspect I'll need pony up for a pair of the 512 GB SanDisks (at $600 each).

[Kayaker72]

Thanks John.

The only other thing I would consider is heat. I have heard that there is a difference between card brands. This is a new review site to me, but, after a search, I found this, granted that was generated moving 85 GB of 8K video. In looking at the SanDisk review, they also found that SanDisk started throttling speed as it went above 65 C, but they still gave the 512 GB SanDisk their gold seal.

It seems that they are updating their comparison tables with each Type B card review. The Delkin Black is looking very good, and actually starting to get to much better "sustained" write speeds (double the Sandisk) when transferring while maintaining cooler temps. But, then looking at the data that they consider more real world, the two is virtually identical and 15 GB in 31 secs = 483 MB/sec. So, the main benefit may be cooler temps.

I use both the 128 GB (my original) and 512 GB SanDisk cards (bought for Laguna Seca trip). Both great and I haven't noticed a difference, but that is how I shoot. I have noticed that after pulling them out of the card reader, they are hot. No doubt about that.

Enjoy the R3 .

[neuroanatomist]

Thanks for the info, Brant. Like you, I tend to shoot in short bursts so probably a smaller card would be fine. Based on the file size of the R6 (slightly more MP than the R3), even a 64 GB will hold close to 3,000 RAW images. I can’t imaging shooting that many frames in a session, even at 30 fps, and I generally prefer more cards than bigger ones. If I shot video I may feel differently…but I don’t. So given that, I’ll probably pick up a pair of 64 GB CFe cards and see how it goes.

I also need to sort out the SD cards. I have a pair of 64 GB cards that I swap for my EOS R (they came in a bundle with the camera, along with a couple of video accessories that I gave away). However, they’re UHS-I cards and while that wasn’t an issue with the R, I think they’ll be too slow for the R3. I’ll pick up a pair of 64 GB UHS-II SD cards and see how they perform with writing RAW simultaneously to CFe and SD. If that slows it down, I’ll write just to the CFe and periodically Image Copy the files over to the SD during downtime (to mitigate against card failure).

I’ll definitely enjoy the R3, whenever it comes. In the meantime, I have an RF 70-200/2.8 showing up next week.

[Joel Eade]

I too usually prefer multiple smaller cards.

I used some very inexpensive 64gb Sandisk SDII cards in the R5 at Laguna Seca and had no issues running into the buffer.

I did notice however a marked reduction in speed when downloading the images for processing and archiving.

[DavidEccleston]

As the owner of a dead SanDisk Extreme card, yes, multiple decently sized cards are the way to go. You don't want to switch cards too often, but you don't want to lose your only storage all at once either.

[Jonathan Huyer]

I've been using the 512 GB Sandisk CFexpress cards and so far the biggest burst that I've fired is when these two young grizzlies starting play fighting in front of me. I held the shutter button down for a solid 2 minutes, blasting 16 fps @ 20 MP the whole way through. I didn't check how hot the card got, but I'm happy to report that it did the job quite well.

[Kayaker72]

I used some very inexpensive 64gb Sandisk SDII cards in the R5 at Laguna Seca and had no issues running into the buffer.

I had previously mothballed my UHS-I cards. After talking with you, watching you do this and looking at my own usage, they are back in circulation.

For my usage, UHS-I is fine, largely because the R5 has a surprisingly good sized buffer. Going with Bryan's data, you are still looking at 151 shots at 12 fps to UHS-I SD card. On the 5DIV, Bryan got 21-36 shots at 7 FPS. Huge improvement. I tend to shoot action shots 1-3 second bursts, which means, I could do ~5 x 30 frame bursts before the buffer filled while the R5 vs ~1 on the 5DIV. After that, it is a matter of how long to clear the buffer.

However, I bought the UHS-II and CFexpress cards. I am primarily using those, but the UHS-I cards in occasional use too and I have yet to have an issue. In the future, I'll probably still pick up CFexpress/UHS-II cards. Just nice to have faster transfer speeds and not having to worry about in camera limitations for when I finally see Big Foot in the woods.

[Kayaker72]

Thanks for the info, Brant. Like you, I tend to shoot in short bursts so probably a smaller card would be fine. Based on the file size of the R6 (slightly more MP than the R3), even a 64 GB will hold close to 3,000 RAW images. I can’t imaging shooting that many frames in a session, even at 30 fps, and I generally prefer more cards than bigger ones. If I shot video I may feel differently…but I don’t. So given that, I’ll probably pick up a pair of 64 GB CFe cards and see how it goes.

I also need to sort out the SD cards. I have a pair of 64 GB cards that I swap for my EOS R (they came in a bundle with the camera, along with a couple of video accessories that I gave away). However, they’re UHS-I cards and while that wasn’t an issue with the R, I think they’ll be too slow for the R3. I’ll pick up a pair of 64 GB UHS-II SD cards and see how they perform with writing RAW simultaneously to CFe and SD. If that slows it down, I’ll write just to the CFe and periodically Image Copy the files over to the SD during downtime (to mitigate against card failure).

I’ll definitely enjoy the R3, whenever it comes. In the meantime, I have an RF 70-200/2.8 showing up next week.

Regards to the RF 70-200 F/2.8, nice! Everything about it seems good, but the size and ability to pack it upright in particular makes it appealing. I am not sure what my first RF lens will be and when I will start making the transition, but that lens could easily end up in my bag.

After my last post, I took a look at the R3 specs a bit more. Canon has the buffer depth rated at 150 RAW images. Assuming 30 MB per file for the R3, 60 MB/sec UHS-I, 180 MB/sec UHS-II and 500 MB/sec CFE, you are looking at 2 fps, 6 fps and ~17 fps after the buffer has filled and 75 sec, 25 sec, 9 seconds to clear the buffer. If you ever fill it.

As Joel proved, UHS-I cards will really work just fine for most of us even in action instances. Most of us just will not take that many images that quickly. That said, UHS-II does seem to strike a nice balance.

[neuroanatomist]

Regards to the RF 70-200 F/2.8, nice! Everything about it seems good, but the size and ability to pack it upright in particular makes it appealing. I am not sure what my first RF lens will be and when I will start making the transition, but that lens could easily end up in my bag.

My first RF lens was the 24-105/4L, which I bought along with my EOS R. That was before the 24-70/2.8L IS came out, and I now need to decide if I replace my EF 24-70/2.8 II with the RF version. For this sort of thing, I find analyzing the EXIF data from my library to be very helpful. As a Mac user, I used to use Aperture for my library organization, and I had an app called Aperture Inspector that graphed out usage by lens, focal length, aperture, etc. I was disappointed when Apple killed Aperture, and I was forced to use Photos for my library (I've been reluctant to move to LR even though I use PS CC – mostly because I prefer DxO PhotoLab for RAW conversions but it doesn't do well with library management). Photos is bearable. I found a Mac App Store download called PhotoStatistica that performs the same analysis and graphing functions as Aperture Inspector.

IMO, the f/2.8 vs. f/4 choice is more difficult with RF lenses. For a higher-end DSLR, an f/2.8 lens means better AF performance (more cross-type points, more high-precision points) and a brighter viewfinder, and those benefits apply regardless of aperture choice. For the R-series bodies, with DPAF and the EVF, the difference really just comes down to how much benefit one derives from the more light and greater OOF blur of a faster aperture. For the 70-200m focal length, it was almost a no-brainer since over 50% of my shots with the EF 70-200/2.8L IS II were taken wider than f/4.

For the EF 24-70/2.8 II, about 25% of my images are wider than f/4, which is still a pretty substantial fraction. But there the trade off is not only size/weight/cost, it's 70mm vs. 105mm at the long end. A bit deeper analysis shows that with the EF 24-70, about 20% of my images are taken at 70mm, but looking at the resulting image sizes only a total of about 6% of the images with the lens are cropped beyond the 1-2 MP loss from correcting rotation and minor framing adjustments, so most of the time a 70mm long end is fine.

But coming at it from the other direction, with a 24-105mm lens about 25% of my images are in the 70-105mm range (applies to the EF lens when I had it as well as the RF lens). So if I have the extra 35mm, I use them about as often as I use the wider aperture. Does that mean I need both? Probably I'll end up buying the RF 24-70/2.8 and seeing which I use the most. If I had to bet, I'll use the 24-70 more but take the 24-105 when I travel.

After my last post, I took a look at the R3 specs a bit more. Canon has the buffer depth rated at 150 RAW images. Assuming 30 MB per file for the R3, 60 MB/sec UHS-I, 180 MB/sec UHS-II and 500 MB/sec CFE, you are looking at 2 fps, 6 fps and ~17 fps after the buffer has filled and 75 sec, 25 sec, 9 seconds to clear the buffer. If you ever fill it.

As Joel proved, UHS-I cards will really work just fine for most of us even in action instances. Most of us just will not take that many images that quickly. That said, UHS-II does seem to strike a nice balance.

I'd probably be fine with the UHS-I cards I have for my EOS R, but I already ordered a pair of 64 GB CFe and a pair of 64 GB SD UHS-II.