QAD Card Practices

  1. When you buy a new camera, buy a set of the fastest cards made for the highest end technology that the camera uses.
    • For instance, the D7500 was designed for UHS-I SD cards, so buy some UHS-I SD cards when you buy that camera. The tricky part is understanding just how fast a card is "optimal" for that new camera. Your camera will never get faster at writing to cards. If faster cards become available after your camera came to market, it's unlikely that your camera will speed up if you use those new cards. If in doubt, buy the highest speed available, which in the case of the D7500 introduction was a 2000x UHS-II card. That way if you end up with a faster UHS-II camera later, you'll be ready.
    • Cameras tend to be as slow as the slowest card in them. That applies both to buffer and image review performance. That's why you don't want to put a UHS-II card in one slot and an old, pre-UHS card in the second slot of a two-slot SD camera. Even if you aren't writing to both cards simultaneously, image review performance often will be triggered to the slowest card. Note that some cameras have one "fast" card slot and one "slower" card slot. If you use two cards in those cameras, the camera operations are only as fast as the slower slot. 
      • So: if you want fastest performance use only one fast card in the faster slot. I do this all the time with my D500: the XQD cards are about double the speed of the fastest SD cards, so I simply shoot with an XQD card only in the camera most of the time.
    • Cameras tend to slow a bit with the largest card capacities. This has varied over time and with card type, but for SD and CompactFlash there have been "sweet spots" in performance well below the largest capacities. For example, 32GB cards tend to be faster than 128GB. This is due to some overhead in managing the additional chips in the high capacity cards. The loss of speed isn't typically severe, but if you're trying to maximize buffer performance, think smaller card, not bigger. Unfortunately, there's a lot of variability in this, so you have to experiment to find what size is fastest with your card and camera vendor.
    • If speed isn't important to you, consider buying lots of older, inexpensive cards and just shooting with them once (much like film, they become your "original" after being taken out of the camera, and you just build an archive of shot images stored on cards). Certainly with SD cards, a wallet of such cards isn't particularly big, but can provide a simple "back-up" system while traveling.
  2. Best erasure practices:
    • Always use Format in the camera to fully erase cards. Yes, there are some subtle differences in how the camera makers think the card is formatted, thus their formatting procedures always take preference over others (see low level format below, though).
    • Minimize your use of deletion of images in camera, and be particularly wary of doing this as your card gets close to being full. In-camera deletion used to be a very big issue, as the file management within many early digital cameras was highly suspect. Over the years things have gotten better, but there are still bugs lurking in many cameras, and the problem with file deletion is that it is telling the system which sectors are free to write to. A bad file deletion may lose more than the file you deleted. 
    • If you connect your camera to a computer or put your card in a card reader connected to a computer, be wary of programs that "touch" the file structure of the card and write files to it. You generally don't want your computer to build a file index on your cards (e.g. Spotlight on Macs), for instance. 
    • If you encounter a card that has a problem, sometimes a low level format is what is needed (to eliminate bad sectors and restructure the card the way it was shipped). For SD cards, the answer is simple: use Panasonic's card formatter. Also available at SD Association. This utility is the one to use to restore any SD card to the way it (should have) shipped from the factory. CompactFlash doesn't have any such utility, so you're going to have to use an OS utility and get the parameters right:
      • <128GB: FAT32 (sometimes called MS-DOS file system or similar)
      • >128GB: exFAT
      • Partition scheme: Master Boot Record
  3. Card failures happen. More often than camera failures. The most typical symptom of a card failure of some sort is you see the image fine on the camera's LCD (because you're looking at the embedded JPEG preview) but when you go to work on the raw file (or even full JPEG) you get bands of color, usually across the bottom of the image. This is typically an indicator that the full file data didn't get written to the card correctly, and often happens when the camera's write mechanism is stressing the card (i.e. when you're shooting long bursts of continuous images). 
    • If all your cards produce the same problem, suspect the camera. Have it looked at for a card write mechanism failure.
    • If only one of your cards produces this problem, suspect the card. Do a low-level format (see above) and try again. If the problem persists, retire the card.
  4. It's important to understand the folder structure on the card and how your computer/software sees it. 
    • For still images, there will be a DCIM folder (Digital Camera IMages) at the root level on the card.
      • Inside this folder may be one or more folders created by a camera or cameras (if you moved the card between cameras). Since a folder can only have 999 images in it by the standards definition, if you shoot a lot of images, you'll have multiple folders on the card. If you are manually moving images to your computer, this is important to note: you have to move images from multiple folders to your computer or else you will lose images! Even some automated software gets this wrong (particularly if it detects differences in the sub-folder naming). So always verify that all images on the card got transferred.
      • Outside the DCIM folder there may be other files the camera has written. Things like Save Settings files, for example. It's important that you understand all the files that your camera can create and where it puts them. Many cameras put non-image files outside the DCIM folder. So if you wanted to save those files, you'd need to transfer them manually.
    • For video images, some cameras store them in the DCIM folder, while other cameras (e.g. Sony) use the AVCHD standard, which means that a complex folder structure that was defined for DVD and Blu-Ray players is used, and the actual "video" file is buried in there (the actual video "clips" are in root/PRIVATE/AVCHD/BDMV/STREAM). 
text and images © 2017 Thom Hogan
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