Memory Cards

[Raid]

About a decade ago most DSLR Cameras used Compact Flash Cards. Then some started appearing with SD card slots, even an early 1D came with dual CF/SD slots. At the time it was thought that SD would dominate because they were faster. The CF group came back with even faster versions and the 1D's went back to dual CF slots.

Today it looks as if CF has stoped at 160MBps while SD is now at 250MBps. SD has won the race for speed and the 7D2 will come with both CF & SD slots. Does this means that Canon will transition all their bodies, even the 1Ds to SD?

Will Canon move to CFast because it's capable of 1GBps speeds.

What ever happens its going to be an expensive exercise for those on CF to transition to a new format.

[peety3]

There's more to it than just speed. SD cards have exposed contacts, while CF contacts are out of the path of grubby fingers, etc. I've had numerous SD cards go dark because the plastic finger between contacts came loose and got in the way; removing the finger brought the card back to life, but what happens if the finger gets in the way "when I'm not looking" - will I lose images because of it?

If nothing else, all of Canon's big commercial customers have invested lots of dough in CF cards. At best, they'd go back to a CF&SD format, but it would probably have to be at least one product cycle to go back to CF&SD, then at least two cycles before they could "safely" go SD&SD. Any faster and the commercial companies will switch platforms just to say "we hate you!". I had been building an arsenal of mixed cards, with a 1D3 as my (old) primary camera. When I picked up two 1Dx bodies, I started going hard-core into 160MB/sec CF cards, but had to circle back and pick up some 95MB/sec SD cards for my wife's 5D3 (and 95 was the fastest I was seeing just a few months ago).

[Kayaker72]

Interesting. I need to even try the 90 MB/s SD cards. My current 45 MB/s SD cards do not even come close to that performance.

But I also wonder about the ultimate utility of the speed, for most shooting circumstances. The 5DIII, 25 MB files, 6 fps = 150 MB/s. So, does a 5DIII shooter need much more than 160 MB/s? 7DII and 1DX shooters with the 10 fps and 12 fps, sure, mathematically, I can see the need. But the current 7D can rattle off 23-25 RAW files before the buffer fills, I believe the 1DX is rated at 35 but I've heard actually shoots around 50 RAW files before the buffer fills. How big of niche is the market for people that pull off >50 shot bursts? Does it exist, considering that is 5 seconds, I am sure it does. Probably looking at sport and wildlife photographers.

For still photographers, I guess the question I am wondering is how big of burst is needed? 50? 100? 150? Write rate to cards is one way to capture this, but expanded memory on camera is another.

I see the real application for these SD cards as 4K video. Quick calcs and 60 fps of ~10 MB per frame (assuming no jpg compression) would be 600 MB/s. If you want 120 fps, then 1.2 GB/s. So, RAW video, especially 4K, may be the main market for the speed.

That is probably where all of this is going. But I don't do video much, so I may be off.

[jrw]

Have camera bodies with dual slots both CF/SD and dual CF. Have lots of both. Do find that the CF cards seem to be easier to keep track of and have fewer issues with dirty contacts, like none, compared to SD cards.
I have never filled a buffer yet and that includes older bodies. I do a LOT of sports shooting and have yet to find a situation where I can't watch what is happening and get the shot with a relatively short burst. Perhaps starting out in the era of film has forced the development of a bit of patience to wait for the action to happen and select moments as they happen. I do appreciate not having as many files to sort through after a long day event as some other shooters do and send far fewer to the recycle bin. As one older shooter expressed it to me " How much really changes between frames at higher rates? I want good shots. If I want video I'll use a video cam."

[Jonathan Huyer]

Yes some SD cards have speeds over 250 MB/s but at the same time they indicate the sustained write speed for HD video is only 30 MB/s. Compare that to a SanDisk 160 MB/s CF card, which has a sustained write speed of 65 MB/s. I have no idea what those sustained speeds mean in the real world, but I'm curious if it is some kind of inherent limitation in the SD card compared to a CF.

Meanwhile, my 160 MB/s cards work brilliantly in the 1DX and will give me 50 raw images in a single burst at 12 fps. It does come in handy on those rare occasions when you have a fleeting wildlife encounter. And yes it means you have lots more images to delete when you get home, but it also means you have a lot more keepers

[Busted Knuckles]

sandisk just released a sustained 90 mb/sec write which is supposed to meet the 4k video demands.

the Canon pipeline to the SD card I don't think can make use of this write capacity. I have chosen to get a fast CF card as the pipeline to the card I believe is much faster.

No one is currently thinking about 4k raw - always compressed.. Only recently has the magic lantern guys gotten 2k raw to run and it is dicey at times from what I read on the forums - I have yet to try it. 2k Raw is running in on 100mbs/sec which is mind boggling what a lengthy shoot would need for storage.

[Kayaker72]

Had a discussion with a friend about memory cards. In it, I brought up the tests where Rob Galbraith evaluated a variety of cards with different cameras. It's too bad he hasn't tested all cameras, as the camera itself does seem to be the limiting factor with faster cards.

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Canon 5DIII

It interested me that write rate for JPGs on the 5DIII was slower than the RAW. I assume the JPGs are limited by the 5DIII processor. With the D800, the JPG/RAW are very similar, but overall, RAWs write slower than on the 5DIII.

[Raid]

There is a very big difference between Write Speed and Sustained Write Speed. While most understand that the speed of a Hard Disk can vary because it needs to position the heads and then wait for the sector, (a mechanical operation) they find it hard to believe that electronics can have the same limitations. I have looked for a simple explanation of why Flash Write Speed varies, but I haven't found one, so lets just say it does.

The Write Speed of Flash Memory is the fastest speed that data can be transferred, this could also be call the Burst Rate. While Sustained Write Speed is the transfer speed that the Flash Memory can accept without a pause, this could also be called Minimum Transfer Rate or Worst Case Transfer Rate. As you can see Sustained Write speed is very important to video photography, it's important to understand that both of these measures are important to still photographers.

If you have two cards both with Write Speeds of 160MBs but one has a Sustained Write Speed of 90MBs and the other 60MBs, the card with the fastest Sustained Speed will give still photographers better results (less buffering).

Back to the original subject:

There could be one other reason why the 7DII has both SD and CF slots. To allow 7D, XXXD and XXD users to transition to the 7DII without replacing Flash cards.

I don't know if dual slots is significant as to what will come. I do know that the CF Group hasn't done anything with CF since 2012 (UDMA7) but they have been working on CFast.

[HDNitehawk]

For those of us that have been around a while on the forum, we had a thread about this some time ago for stills.

Brant you were involved in the discussion. We tested various cards and the highest speed and I thought we found that the highest speed a camera was writing was around 60mb/s. At the time I had several 100 mb/s cards that I tested.

Speed appeared to be camera limited, I wonder if these newer high speed cards would help at all.

[Raid]

Speed appeared to be camera limited, I wonder if these newer high speed cards would help at all.

There is always something limiting the speed of transfer.

You will find Cameras that have a different transfer rate for JPG & RAW, this has to do with microprocessor, not the interface. My first DSLR (350D) had a RAW transfer rate of around 8MBs, so fast cards wouldn't help. My second is a 7D which was around 60MBs and with firmware 2 (UDMA7) it got even faster (100+MBs). Unfortunately, the camera makers don't publish data on how fast they can transfer data. This is done because it would be way to confusing to be understood by mortals. What they have started doing is stating that a minimum speed card is required for correct video recording. While this isn't much it does help.

In a previous thread about a new camera (I think the 1DC) they talked about shooting a video then selecting then selecting the best frame to print as a still. So the future is 25fps+ and no more shutter count limits.