Choosing the Best Memory Card For Your Digital Camera

The Executive Summary about Digital Memory Cards by Steve Denton

Which brand of memory card should I buy? How big of a card do I need? Is one large card better than multiple small cards? Does the speed rating of the card matter? Cameras and lenses can be easily replaced, especially if they are insured.

Memory Card Reliability

The first thing to look at is the memory card itself. Most entry level and amateur level cameras use SD (Secure Digital) memory cards. Most professional and prosumer cameras use CF (Compact Flash cards). In general, Compact Flash cards tend to cost more, but offer higher read/write speeds, larger capacities and be less prone to failure than the Secure Digital Cards. This article will focus on those two card types.

While there are many manufacturers of memory card out there, the top tier, and the choice of the vast majority of pros, are SanDisk and Lexar. SanDisk claims a MTBF (Mean Time Before Failure) of over 1,000,000 hours – that’s almost 115 years before the average card fails. Their cards are rated for over 10,000 insertions. A sophisticated defect and error management system can rewrite data from a defective sector to a good sector on the fly. SanDisks built in Error Detection Code and Error Correction Code to try to recover corrupted data automatically.

The regular (blue) SanDisk CF card has an operating temperature range from 0°C to 70°C (32°F to 158°F). The Extreme III cards are rated with an operating range of -25°C to 85°C (-13°F to 185°F). Overall the reliability from their Compact Flash cards is significantly better than even the best hard drives on the market today.

One important note: there are many fake SanDisk cards in the marketplace. Some of these are cheaper manufacturers cards with SanDisk stickers and packaging. Our best advice, is to only buy from a reputable retailer like Amazon.com or BHPhotoVideo.com, and avoid buying memory cards that appear too cheap, are for sale on eBay, or some market stall while traveling etc – stick to reputable sources that are authorized dealers.

However, even with the best cards, errors do still occur. There are many, many millions of these cards in circulation today. If you remove the card from the camera before the camera has finished writing the data, you’ll lose images that the camera hasn’t completed writing. It’s very easy to accidentally format a card, especially if you use multiple cards. There are reports of certain software applications importing the images from the card, then the user deleting the card, only to find that the application only imported the thumbnail JPEGs that were embedded into the RAW image files, not the actual RAW image files. In virtually all these cases, most of the images are recoverable using data recovery software.

Bottom line, trying to save $20 on a memory card for a camera/lens system that costs hundred or thousands of dollars makes very little sense. If you stick with the top tier brands, memory cards are very, very reliable, and they are far from the weakest link in the typical users workflow.

Card Sizes: One Large Card vs. Multiple Small Cards

How much card space you need depends on what format you shoot (RAW files are significantly larger than JPEG’s), and how many shots you are likely to take between getting to a computer to clear off and backup the cards. If I’m traveling, I’ve usually got a laptop with me so I can backup my cards every evening. On a Nikon D200 containing a blank 8Gb SanDisk card, the camera claims 480 shots are available for RAW shooting. My Nikon D300 regularly gets around 700 shots on an 8Gb card using Lossless Compressed NEF files. If you switch the D200 to Fine JPEG, it shows 1,300 shots available. If you select RAW plus Fine JPEG, it shows 354 shots available. Your cameras manual will contain a table showing similar data for your particular model.

There are conflicting opinions as to if one large card is better, or if many smaller cards are. The argument for smaller cards is, that if your card fails or you drop your camera in the ocean, you lose less data. The argument for larger cards, is card failure is very rare, and largely recoverable. You also risk a much higher chance of dropping a card, getting it wet, sitting on it, losing it, accidentally erasing it, forgetting it or leaving it in your hotel room if you are managing multiple cards.

Uploading to computer can take a long time – putting in one large card and leaving it to upload is a lot less work than swapping multiple smaller cards and uploading each one manually. A 4Gb size card is ideal if you back up to DVD – it’s the largest card size that will completely fit onto a DVD, making the back up a simple drag and drop.

There is no right or wrong answer, we’ve standardized on 8Gb Compact Flash cards – mainly because they hold a decent number of shots and usually offer the best price per gigabyte. As larger cards become more common and prices drop further, we’ll go to larger sized cards.

Card Speed: How Fast Do I Need?

Memory cards come in a wide range of speeds, and the faster the card, the more expensive. How fast of a card you need depends on a number of items:

If you are uploading via cable from your camera, your upload speed is limited by the camera. For the absolute fastest uploads, use a card that supports UDMA (like the SanDisk Extreme IV’s, SanDisk Ducati’s, and Lexar 300x) in a FireWire reader. For example, the SanDisk Ultra II 8Gb card claims a 15 Mb/second read speed, so that would take almost 9 minutes to upload on an optimally configured system. The 8Gb Ducati card claims a 45Mb/second speed, so would take less than three minutes to upload.

If you shoot landscape or take several minutes to compose each shot, then you don’t need a fast card. If you are shooting non-stop action and taking sequence after sequence at 8fps, you’ll need as fast a card as possible. Cameras like the D200 and D300 have a big enough on board buffer to store about 17 shots if you are shooting RAW. Once you’ve taken a picture, the camera writes it to the memory card and erases it from the buffer as soon as it can. Once the buffer is full, the camera won’t let you take another picture until it’s written an image to the memory card and made room in the buffer. Then if you stop shooting, the Ultra II may take a minute or so to get the buffer cleared and all written to the card. The Ducati card will allow the camera to write the images to the card and clear the buffer in seconds.

If you take your time to compose each shot, and upload speed isn’t important to you, then memory card speed isn’t important. If you are shooting action or sports and use a rapid frame rate frequently, then you want the fastest card, and camera, that you can afford.

Data Recovery Whether you’ve accidentally removed your memory card while the camera was still writing, deleted or formatted the wrong card, or the card has developed an error, it’s usually possible to retrieve some, if not all of the lost data.

The higher end cards from both SanDisk and Lexar come with their respective data recovery software packages on CD. SanDisk’s is called RescuePro, and Lexar’s is called Image Rescue.

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