I quite often see threads with questions like "an image on my memory card is corrupt" or "all my pictures are corrupt, what can I do"? I often write out an answer, but I've written bits and pieces so many times I figured I'd write it once then just link to it when I need to. This is just my opinion, and I'm sure other technical guys will voice theirs below, I suggest not clogging up the thread with lots of "thanks" posts until the other guys have had their say too.
Unfortunately it's virtually impossible to know what causes corrupt memory cards. It could be:
- The camera doing something wrong (it's a small computer, and we know how computers are
- A fault with the memory card
- A good camera and a good memory card just having a bad day
- A bad card reader or cable
- A hard drive with a small section not working properly
- Faulty ram (memory) inside the computer
- A cosmic ray
Here's what I suggest people do, in this approximate order, when they see a corrupt image on their memory card:
1. Put the card into another computer with a different memory card reader and cable to see if it's the card or the computer. If it works on the other computer see computer diagnostics below.
2. Try the above but make sure your card reader's plugged directly into the computer, not into a hub of any kind.
3. Put the card in the camera that took the image, connect the camera to the computer using USB, try to copy the images off that way.
4. Run recovery software over the memory card. There's a lot of different pieces of software, I'm not going to recommend one in particular. There's a free one for PC I sometimes try first that can hopefully still be found here
.5. Send the card to an image recovery specialist. This can be pretty expensive.
MOST IMPORTANT: do not write to a memory card that's causing a problem. Mark it clearly and put it aside until you prove it's good.
Computer diagnostics
If the images are viewable on another PC you need to work out what's wrong with your PC. I suggest you do things in this order
1. Buy a new memory card reader and cable
- Sandisk and Transcend are good brands2. Run Memtest x86
overnight to try to find memory problems. It's free (though someone gets suckers to pay for it), it's for PC, it may work on mac I don't know but macs are x86. It's a bootable CD image, just write the image to a CD then reboot.3. Run the memory card diagnostics linked below.
4. Try to find software to test your hard disk - I don't know of any sorry.
5. Perhaps buy a new power supply for your computer. Perhaps not. Bad power can cause many problems. Talk to a computer technician about it or start a thread before you bother with this.
6. Buy a new computer. This is extreme, but I'm lazy, fixing tricky problems with computers is difficult, time is valuable and images are irreplaceable.
Memory card diagnostics
If a card fails once I tend to throw it out, but if it's questionable you can always run a card testing program over it. I don't know how reliable it is, but I use this piece of software on PCs to test memory cards.
Reliable memory cards
I use two types of memory cards:
- Transcend Industrial
- Sandisk Extreme
I prefer Transcend Industrial as they use higher quality SLC memory, plus they have built in error checking and correction. Sandisk and cheaper Transcend cards use lower quality MLC memory, though how important it is is debatable. The difference is SLC cells store one bit per cell, MLC store multiple, and the higher the information density the higher the error rate. MLC cards tend to be faster as well. If you have dual slots use MLC cards as they're faster and cheaper and almost as reliable. If you only have one slot I think SLC cards are a good investment. I've found cheaper Transcend memory cards less reliable than the industrial cards, and Sandisk even being MLC has always been reliable for me. The quality of MLC cards varies, cheap cards are generally made from cheap components - caveat emptor, you usually get what you pay for.
If there are questions or clarifications required please ask, but I suggest we keep this as more of a reference thread than a helping everyone thread. As I said above other technical guys please add to what I've said or correct anything that's wrong.
I hope that helps some people out
