SD, CF cards

I've been wondering. In cameras that have dual cards, why do all (?) cameras use 1 SD and 1 CF cards. Wouldn't it be more space efficient to use 2 SD cards? Haven't been able to get an answer.

CF cards offer faster transfer rates, which allows cameras with high frame rates to write the frame buffer to the card quicker. Since most high end cameras have fast frame rates, CF cards have become standard at the high end, and many pros have a lot invested in the format (CF cards are quite a bit more expensive than SD cards).

The 1DX Mark II moved from a CF/SD combination to a CFast/CF combo. CFast is required for 4K video capture, and I expect this pairing to waterfall down across the rest of the pro-level bodies (5D, 7D, etc) as they are updated.

mikepj wrote in post #18065516
The 1DX Mark II moved from a CF/SD combination to a CFast/CF combo. CFast is required for 4K video capture, and I expect this pairing to waterfall down across the rest of the pro-level bodies (5D, 7D, etc) as they are updated.

The 1DX had dual CF card slots, no?

And why aren't CF cards sufficient for 4K video?

frugivore wrote in post #18065521
The 1DX had dual CF card slots, no?

And why aren't CF cards sufficient for 4K video?

You are correct. Previous 1D cameras had a CF/SD layout, but the 1DX switched to dual CF.

As for the video issue, Compact Flash has a theoretical speed limit of 160MB/sec, while CFast can go up to 600MB/sec. Even though Compact Flash can hit 160MB/sec, the current fastest cards hover around 90-100MB/sec.

The 1DX can support 4K video at 60fps, which has a data rate of 100MB/sec. The 1DX2 will let you record 4K to the CF card, but the buffer will fill after a period of time and prevent you from recording a longer video. The CFast cards, on the other hand, will keep up with the 4K stream without any problems.

It's also worth noting that for 14 fps bursts on the 1DX2, the camera will run out of buffer after 73 RAW images when using CF cards, but if you are using CFast cards the buffer will hold on until 170 RAW images.

You can read more about the new format here:
https://learn.usa.cano​n.com …i/eos1dx-mkii-cfast.htmlp

Another point to keep in mind about read/write speeds on camera memory cards: The key point where the speed is an advantage isn't during capture, but during transfer.

I also greatly prefer CF cards over SD for their physical size. I've yet to lose a CF card after more than a decade of handling them. I've lost a few SD cards and several of those bloody micro SD cards. (Seriously, there are multiple epub copies of public domain classics in English literature kicking around somewhere because I dropped the bloody card and somehow lost it. Which is actually kind of impressive in a way.)

one other advantage of CF card over SD is the lack of a sliding lock doodad ... i've had that plastic lock piece fall out on a couple SD cards rendering them worthless.

Joker-USMC wrote in post #18136992
one other advantage of CF card over SD is the lack of a sliding lock doodad ... i've had that plastic lock piece fall out on a couple SD cards rendering them worthless.

Here we go again, the Navy (I was an O-5) helping out the Marines.

See http://www.wikihow.com​/Fix-a-Broken-Lock-on-SD-Cards

I will not consider any camera with an SD card, all I seem to have to do is touch one to kill it. I'll even try to avoid touching the contacts, but even so touch it and it's dead! The odd thing is that I am into electronics and as such handle components that are SSD's all the time. If I'm careful I can usually manage not to kill them if I don't earth up. So it seems to be SD card specific.

On the other hand the 1GB Jessops brand CF card that I got with my new Canon EOS 300D in 2005, when I swapped from analogue to digital, and Pentax to Canon is still going strong, It usually sits in my backup/second camera 20D these days.

Alan

I've had good luck with both types of cards, as long as they're from a higher end company (Sandisk, Lexar, etc).

I've not had such great luck with other brands of SD cards (Centon and EyeFi) and have had to return them for repair/replacement before because they simply came apart. I ended up super-gluing the edges of those cards because even the replacements started separating again. A little dot on the end of a toothpick is all it takes to glue the edges, and you'll have a physically reliable card after that, just be sure not to get it near the lock switch or you can get yourself into trouble. I try to be very careful with them, especially the SD's, but few of my Lexar's have even been through the washer/dryer after being left in a pocket, and all have come out fine with no data loss.

That said, I much prefer CF cards for their clearly more robust design. I've had no issues whatsoever with any CF card I've ever owned, even with brands I had never heard of before and received as a promo deal.

I too have had good experiences with both types of cards and think each has its own advantages as mentioned. Mikepj, I appreciate the information you shared here, take care everyone.

frugivore wrote in post #18065521
The 1DX had dual CF card slots, no?

And why aren't CF cards sufficient for 4K video?

Yes, and CF cards are sufficient for 4K,. but not all CF cards are capable. Particularly where Canon 4K is concerned.


All C-Fast cards are capable of handling the high demands of Canon's 4K Mjpeg

Dual SD cards would be like dual worn out sneakers.

Cf cards are faster, easier to handle, and last longer/more reliable.

SD has become the standard, but it is a poor standard as far as I am concerned.

CyberDyneSystems wrote in post #18164285
Dual SD cards would be like dual worn out sneakers.

Cf cards are faster, easier to handle, and last longer/more reliable.

SD has become the standard, but it is a poor standard as far as I am concerned.

Not sure I would agree. Lexar wins at the moment with a speed read speed of up to300 MB/s (or 2000x) but doesn’t publish a write speed. Some independent "testers" peg the sustained write at almost 250 MB/s of sustained write speed out of it.

At a wedding Saturday I had a conversation with the video guy. Some impressive Sony professional video equipment by the way. He was shooting 4K and using the Lexar card. When I asked about issues he said "the camera can't keep up with the card" and had a funny smile. I thought about that for a moment I realized he was saying the card can handle anything the camera was capable of.

The reliability part as well I'm not certain of. If you factor in the potential of bent pins and look at the overall picture, it might be a toss up.

re: Reliability I am using purely anecdotal evidence. A case of one user.

I have had one CF card fail since I got my first 2MB one in the late 1990s (that card still works) And ZERO DOA CF cards.

I've purchased about 60 CF cards (guesstimating) including ones that are long since out of service or used as give aways or data transfer...

The one CF card that did fail was a 256MB sandisk that spent it's life in my 4MP "digital elph". That stylish little brick of a camera died before the CF card did.

I started getting SD cards when they put a slot for them in the 1D mark II in 2005. Despite the fact that they were always used less for "back up" I have had (I believe) 5 fail and two arrive dead/unuseable out of the package. ( Total 7 failures )

My CF card vs. SD card habits would be about 5 to 1 (5 CF cards for every SD card I have ever purchased, keeping in mind that CF was around for years before SD)

The SD failure rate is 7 vs 1 total. With the 5X CF card inventory, does that equate to an estimated approx 35 to one failure rate SD vs. CF?

If this is my experience, would I not be wise to prefer CF?

For semi pro/pro level body, such as 5D3, the reduction in size from CF to SD is insignificant. Even if they have 2 SD slot, they won't make the body smaller. Redction in form factor size only play a rule in things that wants to go small, such as P&S, smaller body such as Rebels, or mirrorless, etc

From cost point of view, SD slot is cheaper than CF slot due to the reduction in pin count and contact type, but for body in $3000 range, it hardly makes differences.

My take is that manufactures keep the CF just to distinguish so call "pro/prosumer" model from entry level model. There is no other reasons.

Now, to say the reason is because CF is more reliable than SD, it is more of a chicken & egg analogy. If flash manufactures wants, SD can be make as reliable as CF, maybe even more reliable due to way of manufacturing SD. SD can also be made sufficiently fast even with UHS-I interface (think Sandisk ExtremePro 90/95 type of SD). But they don't, because SD is a high volume commodity that the demand for high quality isn't as strict as the niche, low volume CF. One day, if (but not likely), 5D or 1D type of body start to come in SD format only, you will see super reliable SDs marketed in high price range for professional use