Minimum speed CF card required for a 7D?

Question

What is the minimum speed CF card required for using a 7D for both recording 1080p video and also continuous shooting for RAW+JPEG?

Similar to Should I get a fast CF card? i essentially want to know if i need to buy a more expensive faster card or wether the standard cards are sufficient. Difference between questions is:

• a) I want to know what minimum speed is required.
• b) I will also be using it for video (i have seen in the past on other cameras video not recording correctly because an SD card was too slow).

Asked by mundeep

Answer

For video I believe the requirements would be a card that can write 10 MB/s (mega bytes per second). This equals to 66x speed for a Compact Flash card. For shooting stills it's possible to get a longer burst with a faster card. If you want maximum burst length, get the quickest CF card you can afford.

The math would be: 66 * 150kB/s = 9900kB/s ~ 10MB/s

• 66x = 10 mb/s = similar to Class 10 on SD cards
• 133x = 20 MB/s
• 200x = 30 MB/s
• 266x = 40 MB/s
• 333x = 50 MB/s
• 400x = 60 MB/s
• 466x = 70 MB/s
• 533x = 80 MB/s
• 600x = 90 MB/s

Answered by Håkon K. Olafsen

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What should I do about this strange CF behavior, where I lost tonight's pictures?

Question

I have taken over 14,000 photos with my Canon 7D and loaded them into my Windows 7 desktop computer the same way, by inserting the CF card into my computer's reader. The point is that I know how it usually works so this "empty folder" problem is definitely out of the ordinary. To shorten the post I always use the "Safely Remove Hardware and Eject Media" utility before removing the CF. My workflow has been folder based:

• Shoot into a folder.
• Copy the folder to both an internal hard drive for editing etc. and an external hard drive I swap every few days as off-site backup.
• Create a new folder for the next batch of photos, unless the card is about out of space. In that case I format another CF card and remind myself to swap offsite HDs soon. The full card goes in my camera bag, which is my semi-offsite backup against the house burning down.
• When I swap offsite disks I format the CF card in the 7D and move the other CF cards to the "Ok To Use" pocket of my camera bag. If I have time I'll format them as I move them.

I shot tonight's sunset into folder 102EOS7D. Folders 100EOS7D and 101EOS7D had the photos of the two prior shoots since the last offsite backup swap. I put the CF card in the PC and both the last two folders were empty, 101 and 102. I put the CF card back in the 7D and confirmed that both folders 101 and 102 had pictures in them. I attached a USB CF card reader to the PC and inserted the CF card. Folders 101 and 102 were still empty. I put the CF card back in the 7D and the folders were empty! By just trying to read the CF card two shoots of photos went away! Bummer!

I have the photos from folder 101 and tonight's sunset in folder 102 was boring so I decided to troubleshoot rather than try to recover the CF card. I ran Windows Update and nothing was missing. I reformatted the CF card and shot some photos. I found a USB cable that fits the 7D and successfully downloaded the photos in the new folder 100EOS7D.

Any suggestions? The card is fairly new, only in its second or third offsite-backup-swap cycle. It is the largest capacity I've ever had, a Transcend 400x 64 GB CF card.

More details:

• I always format in the camera, not Windows.
• Losing photos is serious, how do I help keep it from happening again?
• Is this likely a CF card problem, a Windows problem, a problem with my 7D, or ... ?
• I don't know if this is a possibility, but could there be "bad blocks" in the "FAT" (or whatever, don't know tech details) of the CF card that could produce these symptoms?
• Is there a low-level format utility for CF cards that could identify "bad blocks" and "mark them unusable"? Again, I'm not familiar with CF card details.
• Is there something, given the symptoms, I don't know enough to ask?

Asked by Mark Jerde

Answer

CF cards – just like any other storage media – fail every now and then.

In general, when a storage media fails, the symptoms may "look strange" from the perspective of the computer, camera, or any other device that tries to access it. Don't try to over-interpret them; it just failed. You might be able to recover something – for recovery tips, see these two questions: [1], [2].

There is nothing you can do to completely prevent failures, no matter what kind of best practices you try to follow.

To make failures less frequent, you can try to use well-known brands, expensive high-end cards, and cards with a long warranty period. Also remember to throw a card away (or have it replaced) immediately as soon as you notice anything strange.

But most importantly, make sure that losing a single CF card is never a catastrophic event. Use two cards in parallel if your camera supports it. Transfer photos from the card to your laptop or some other backup device frequently. If you don't have access to any kind of computer for a while, use more than one card and rotate them; etc.

Your card will fail, sooner or later. And your hard disk drive will fail, sooner or later. Just plan ahead so that you won't be too upset when it happens. Sure, you may lose some photos, but make sure you don't lose a whole week of memories.

Answered by Jukka Suomela

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Is a card reader faster than connecting camera via USB?

Question

I've heard that compact flash readers allow your computer to much faster read the photos off the camera, than when you connect your camera over USB.

Is that true? What about other card formats, like SD?

Answer

It depends.

My last camera only connected at USB1.1 speeds, so was slower than using a USB2.0 card reader.

However, if your camera can do USB2.0 or you have a USB1.1 or USB1.0 card reader, you wont see that benefit.

You can get Firewire or ExpressCard card readers for CF cards, which are faster than USB2.0, (and I think generally limited by the speed of the CF card). Sandisk do the fastest of these - see Extreme Firewire Reader and Extreme Pro ExpressCard Adapter.

Of course with USB3.0 devices beginning to appear, these are (theoretically) faster still than Firewire - but you need a machine that supports them (rather than running in USB2.0 backwards compatibility mode) to benefit from this speed.

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What's the difference between CF and SD cards?

Question

What's the difference? Why do professional cameras support CF but amateur models don't?

Both are flash based, both support FAT filesystems — what's the difference?

Answer

Fundamentally they are the same thing in a different package but they work differently.

SD cards use their own protocol which was extended to go beyond 2 GB up to 32 GB with the introduction of SDHC (there were a few 4GB SD cards but not very compatible) and then to support up to 2 TB with the introduction of SDXC. The SD to SDHC transition if you remember was particularly painful as it took years for most other devices (Readers, Picture Frames, Card Readers, Laptops, etc) to catch-up.

CF cards use the IDE protocol which can index large volumes by using pseudo head, track, sector coordinates. That they just kept working as capacities grew, although FAT32 support is used above 2 GB. That makes the protocol more stable and extensible although the next revision is CFast (Compact-Fast) which is based on the SATA protocol.

The larger physical size of Compact Flash also gives them an edge in capacity and they still have a lead in terms of maximum speed as well. This has historically been significant but the gap is so narrow now that it is mostly a case of legacy.

In terms of camera grades, there are high-end models which each type of memory. The Pentax 645D Digital Medium-Format camera uses SDXC cards, Canon top-of-the-line models accept both CF and SD. This leaves only Nikon to exclusively use CF cards in their high-end models.

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