How to avoid a “bad" memory card

Learn how to avoid data loss and how to shop smart.

Nothing can be more frustrating than losing pictures due to memory card problems. I shot some nice pictures at the end of a strenuous hike to a waterfall. As Murphy wants it, those images were lost, not the ones easier to take again.

As a semiconductor professional, I have some insight into Flash technology. Some of it translates into easy to follow guidelines to avoid data corruption. I put technical background information in italics, making it easier for you to skip over these sections.

When should you buy?

Bathtub CurveThe picture shows the failure rate of semiconductors (courtesy of Texas Instruments). The same Bathtub Curve applies to all sorts of failures, not limited to semiconductors.

It is easy to see that most products fail very early in their life or very late in their life.

This means do not put your buying plans off until the last minute, before you set out for a shooting adventure. Give yourself some time to try out your new memory card before you go on your vacation.

If the card fails, it is most likely going to happen right after you bought it.

Large Flash Cards have billions of transistors on them. Even a single impurity (dust) can destroy a chip. Manufacturers sort out devices with impurities early in the manufacturing process.

After sealing and packaging, damage can still occur due to external influence (like Electrostatic Discharge, Mechanical Damage and others) or soft internal errors (like Metal Migration and others). These are responsible for early failures.

There are other causes can lead to memory card failure (below). That is why I usually advice people to buy several smaller cards instead of one giant memory card. The odds of something happening are very low, but if a memory card shows problems, you will only lose a smaller amount of your data.

Handling Tips

Compact Flash
image by: William Hook
  • Never take a memory card out while the camera still writes to it.
    Modern SLRs have large internal frame buffers, allowing us to shoot burst rates exceeding the writing speed of our memory cards. The camera then writes the pictures to the memory card from its internal frame buffer memory. It is easy to forget that this takes more time and in the heat of the moment, we try to swap the card. Always check your camera first to see if it finished writing images.
  • Do not wait until the batteries are empty before you replace them. If the camera loses power during the write cycle you will lose the current picture, but you may also corrupt the file system of the memory card, making it hard to access.
  • Always copy your data and then clear the card by reformatting it. Do not just delete pictures and write new ones indefinitely.
  • Avoid touching the contacts of your memory card.

Restoring Images

Here are some tips that are useful when you are having trouble downloading files from your camera:

  • Try downloading files with different memory-card readers.
  • Use a quality memory-card reader.
  • Try downloading the pictures with your memory card in the camera using the camera software.
  • Try an image rescue software. I have had some success with PhotoRescue in the past. DataRecall completely failed me.

Memory cards are usually very robust. Handle them with the appropriate care, avoiding high humidity, extreme temperatures, and dust to keep them working.

Memory Cards

Ya know, I used to reformat my memory cards all the time. You post made me realize that I haven't done them in quite a while.

Also, I was unaware that image rescue software even existed. The closest I've come to losing pics was when our old Canon konked out. I tried everything and decided that as my last resort I was going to take the card to Target to see if their card reader would work. I set the card aside to get to it eventually...and along comes my 9 y-o tech geek son who works it out within minutes.

Not only did he get the pics download, he got the Canon working!

Never use "DELETE BUTTON" Controversey ?

Please respond to the never use "delete button" controversy.

Camera companies install delete buttons and flash card manufactures have
yet to WARN over the "delete button" corruption debate so WHAT are the

How to avoid a “bad" memory card

Nice! very informative. Thsnks.

memory cards and False Kiva, Canyonlands NP

I was looking at your photographs of Canyonlands National Park and really enjoyed them. Before leaving, I noticed the tutorials button and wow!, I learned things about memory cards that I had never thought of before now. Thanks for sharing your pictures and your expertise!


Thanks for your kind words Penny. Unfortunately I once had trouble with Memory Cards and figured out a few things of interest that helped me avoid disaster.

Very useful info.

Thanks for this article. To be honest, I've never put much thought into the actual technical specifications or the differences between any portable memory. I recently picked up a Vosonic VP8870 to back up my media (this thing is AWESOME, highly recommended), and now I'd really like to add a GOOD collection of memory I can swap out with this and my photographer friends. I will undoubtedly be referring back to this.



You should throughly do a

You should throughly do a read/write using chkflsh a freeware program that will continuously write random data, then read back each sector to confirm everything is fine.

Do this for 48 hour straight and you will find pretty much any problem with the flash memory.

I went through about 3 Adata flash mem cards before I found one that could survive this torture test. I suggest you do that with any new card you have, rather than to wait and hope that it works a month after you bought it.