Corrupted image file.
Over the last month, I’ve been having all kinds of problems with corrupted photographs. I first noticed it after I returned from a big workshop I ran in September, 2011 in the Olympic NP, WA. I found that a few NEF pictures had a vertical line through them and that half of the image had shifted “up” by a few pixels. At first, I assumed the problem was with the CF card I was using, so I took that card out of my photo bag just in case it was bad.
This was the first image where I first noticed the data corruption. See how one side of the file is shifted “up” from the other side?
A few weeks later, I found the problem again. However, this time it was on a JPG. Then, the problem started to get much worse. I found that approximately 5% of my photos appeared corrupted no matter what camera body or memory card combination I used.
More data corruption on a Nikon JPG file. Looks kinda like the Matrix.
So, I started testing to see if I could figure out where the problem originated. First check was my cameras. I never saw any corrupted files on the LCD panel of my Nikon Cameras, so felt that these weren’t issue.
Next was to see if it was a specific CF card. I had corrupted files from all of my CF cards, so it wasn’t a single card problem.
Next was to determine if it was a software issue. My workflow is to ingest my files through Photo Mechanic where I then add copyright and keyword metadata. I ran a test where I brought the photos into my external disk drive through Photo Mechanic and then a separate test where I moved them manually through drag and drop. In both cases, I had corrupted files. Hmm.
Next was to determine if the problem was with my card reader. I use a Lexar Pro CF/SD UDMA card reader and I had heard that there are some incompatibilities between certain card readers and Mac computers. So, to eliminate this as a cause, I moved files to my external drive with the card reader and then again with a direct USB connection to my Nikon D700. In both cases, I had corrupted files.
Ok, at this point, it was clear that the problem wasn’t:
– Card reader
I began to suspect that the problem might be my external disk drive. I’m currently downloading images directly to an OWC 2TB Mercury Elite Pro Quad interface external disk drive. This drive allows me to connect it to the computer via one of four methods: USB, Firewire 400, Firewire 800 or eSATA. My standard protocol is to keep it connected to my MacBook Pro via eSATA. I use an eSATA Express 34mm adapter that plugs into my Mac.
The next series of tests was to download files to my computer’s desktop and then do another download to my external hard drive. The files downloaded to my computer desktop via USB card reader had zero corrupted files. The same files downloaded to the external drive via eSATA connection had two corrupted images. Aha! It was looking like it might be my external hard drive.
It took one more test to get to the bottom of the problem. I connected the same hard drive to my computer via USB (rather than eSATA) and did the download test one more time. This time, I had zero corrupted files.
I called OWC (Other World Computing http://www.macsales.com) and told them my predicament. They immediately said that there was a specific incompatibility with my Express 34mm eSATA adapter and the model of MacBook Pro that I use. For some reason, the chipset for MacBook Pro 5, 1 (five comma one) has problems with some models of Express 34 eSATA cards. OWC said that they would replace my eSATA card with a new one and I’d be up and running within a week.
What a relief. It is really hard to be a professional photographer when you can’t trust your tools. Knowing that I might or might not get corrupted files from any of my cameras at any time, really put the damper on my photography. The kind people at OWC were wonderful to work with. I also talked a bit with Photo Mechanic (http://www.camerabits.com) and they were extremely helpful in helping to troubleshoot the problem.
Now, I’m still using the external hard drive, but I have it connected via USB or Firewire. Once the new eSATA adapter arrives, I’ll go back to high-speed data transfer.