What might have caused this?

This afternoon I took several images at a local park with my D750. Slot 1 is NEF and slot 2 is jpeg fine. When it came time to convert the NEF to DNG, this one file cited an error and couldn't be converted. The slot 2 jpeg image doesn't have the banding at the bottom like this NEF image. The NEF image was only resized and converted to jpeg. No other editing was done to it.

The card was formatted prior to shooting any photos as I tend to reformat between outings. Thanks for any ideas.

You broke it

Obviously something caused an error while the file was being written to the card, but it makes me wonder if it was the card or the camera. This was only the 2nd shot out of 23 taken at that time and the only image to have this problem.

General question for anyone: will the card be okay to continue using after it is formatted again, or might the card be corrupt? In other words, once this happens with a card, does it tend to continue happening? Or might it have been a one-time fluke? The card is a Lexar Professional SD card, 32GB, Class 10, 600x speed.

Likely a write error. I had a card go completely bad on me. Thankfully I can read it in my MacBook's card slot, but it will not format in any camera I put it in. First card I've ever had go bad on me that way.

Would I continue to use it? Not without changing slot two to be a mirror for slot 1 instead of for JPEGs. A single failure is always a crap shoot with regard to predicting recurrence. Cards are relatively cheap, but some images are irreplaceable. I'd at least swap the primary and backup. At least your NEF file was readable.

I have not ventured into dng yet. So not knowing anything about dng, my first thought is if you have another software to try that will open the nef. Assuming that is a fail, then I would say run a chkdsk on the card. Plenty of instructions online. Here is one, (I didn't read it closely, but it looks right)
BEST GUIDE: Steps to fix a corrupt SD Card via Chkdsk

Maybe check disk will reveal that something went wrong on the card. I would follow that up with a format via your computer and then format again in camera.
You could spend some time copying and erasing large blocks of files from your computer to test it out. And of course don't trust it until you have a good run of no problems in camera.

And I guess I owe you a bit of thanks. I tried again to debug the "failed" card I had, sticking it in my MacBook with the hope of being able to somehow reformat it there and then in camera. As I looked at the disk utility it showed that I could not do anything with the card as it was "read only". Turns out that the lock tab somehow got engaged, probably when sliding it into the computer slot. So, knock wood, outside of a card physically splitting on me, I've never had a card go bad.

nickt said:

I have not ventured into dng yet. So not knowing anything about dng, my first thought is if you have another software to try that will open the nef. Assuming that is a fail, then I would say run a chkdsk on the card. Plenty of instructions online. Here is one, (I didn't read it closely, but it looks right)
BEST GUIDE: Steps to fix a corrupt SD Card via Chkdsk

Maybe check disk will reveal that something went wrong on the card. I would follow that up with a format via your computer and then format again in camera.
You could spend some time copying and erasing large blocks of files from your computer to test it out. And of course don't trust it until you have a good run of no problems in camera.

Click to expand...

I believe Cindy is stuck converting because she's on a version of LR/ACR that will not read D750 images.

I was told a long time ago that converting to DNG was a good thing for a whole lot of reasons, so I did for 3 years. It left me without "unmodified originals" for a huge chunk of my catalog since a DNG technically alters the file in the conversion process. This only matters in contest situations, but in those cases it can matter an awful lot if you're required to submit originals. I say this only to let you know that, looking back, I can find absolutely no benefit derived from converting to DNG provided your software can read the native RAW file. If it cannot, I highly recommend keeping the original along with the converted file as well. It'll eat space, but it won't bite.

nickt said:

I have not ventured into dng yet. So not knowing anything about dng, my first thought is if you have another software to try that will open the nef. Assuming that is a fail, then I would say run a chkdsk on the card. Plenty of instructions online. Here is one, (I didn't read it closely, but it looks right)
BEST GUIDE: Steps to fix a corrupt SD Card via Chkdsk

Maybe check disk will reveal that something went wrong on the card. I would follow that up with a format via your computer and then format again in camera.
You could spend some time copying and erasing large blocks of files from your computer to test it out. And of course don't trust it until you have a good run of no problems in camera.

Click to expand...

I can open the NEF which is what I used to covert the above image to jpeg. The file just won't allow conversion to DNG. The image itself is simply OK but isn't one I particularly want or need to keep.

HOWEVER, there is something oddly familiar with seeing this greenish pink band along the edge. I'm sure it happened a long time ago...most likely with my D90. At the time, I didn't give it much thought and can't remember if it was a jpeg or NEF.

I'll try out the card and see if it continues to experience any problems like this. Thanks for the info on corrupt cards, Nick!

BackdoorHippie said:

And I guess I owe you a bit of thanks. I tried again to debug the "failed" card I had, sticking it in my MacBook with the hope of being able to somehow reformat it there and then in camera. As I looked at the disk utility it showed that I could not do anything with the card as it was "read only". Turns out that the lock tab somehow got engaged, probably when sliding it into the computer slot. So, knock wood, outside of a card physically splitting on me, I've never had a card go bad.

Click to expand...

Lol! I did that with a card used in a point-and-shoot camera. Have no idea how the switch got moved.

BackdoorHippie said:

I believe Cindy is stuck converting because she's on a version of LR/ACR that will not read D750 images.

I was told a long time ago that converting to DNG was a good thing for a whole lot of reasons, so I did for 3 years. It left me without "unmodified originals" for a huge chunk of my catalog since a DNG technically alters the file in the conversion process. This only matters in contest situations, but in those cases it can matter an awful lot if you're required to submit originals. I say this only to let you know that, looking back, I can find absolutely no benefit derived from converting to DNG provided your software can read the native RAW file. If it cannot, I highly recommend keeping the original along with the converted file as well. It'll eat space, but it won't bite.

Click to expand...

My computer can read NEF. My only reason for converting to DNG is because smaller sized files are faster to work with (6GB RAM). I have an additional 6GB RAM to put into this computer, but right now the computer is experiencing other problems. Might need to send it in for repair first.

I back up all 3 files (jpeg, DNG, NEF) then remove the NEF from my computer while I'm editing. ASUS once talked me through doing a hard motherboard reset. It split my hard drive into 2 partitions. The OS is now 254GB (with only 34.7GB of space available) while the DATA is 316GB. I need to burn all the drama photos to discs for their department so I can permanently remove the files. Those folders are taking up a lot of space.

I am going to switch the SD cards so that card will be in the jpeg slot. If the card winds up being bad, I'll see what Lexar says. Adorama had a great sale price of $15 when I bought a bunch. Plus I have many San Disk cards, too. Maybe I will go back to using San Disk and keep the Lexar cards to use in a pinch. Thanks for your input, Jake!