Digital BW, The Print

On 27/12/2012 00:48, Kip Babington wrote:
> I've probably used a dozen different
> cards over the years without incident - is this an indication that this
> particular CF card is bad,

Very likely the card is fine.  A card functions just like a disk, and has 
the same frailties - vulnerability to damage of the MBR, partition table 
or FAT. The most common cause of corruption is turning off the camera or 
battery failure whilst the card is still being written. Another common 
cause is use at very low temperatures - standard cards can become 
unreliable below 0C, Sandisk Extreme can manage much lower temps.

It's also not unknown for the OS to get deranged and corrupt the 
filesystem. This occasionally happens because the camera mfr. firmware is 
slightly incompatible with some card mfr's implementation of the CF or 
SDHC standards. Canon at one time had a big problem with Lexar CF, and I 
think Nikon managed the same trick with Sandisk, but both were fixed by 
camera firmware updates.

Another issue that needs to be mentioned is that the vast majority (95% at 
least!) of Sandisk cards sold on eBay (and Amazon marketplace) are Chinese 
counterfeit. They are very close in appearance and often include retail 
packaging, but are cheap low-spec memory, often slow, and without Extreme 
low temperature resilience.

See http://martybugs.net/articles/fakesandisk.cgi for how to tell the 
difference.

If you have one of those, return to the seller for refund or throw it away.

If you have genuine Sandisk I'd suggest low-level formatting the card, 
which will pretty much return it to as-purchased condition. Photorescue 
used to make available a free utility called Cardwiper to do this, not 
sure whether they still do. Then format it in the camera and go and shoot 
test photos to fill the card. If there is no corruption, I'd regard the 
card as fine.

Actual card failures are extremely rare with good brands, and will be 
covered by guarantee. I've never actually seen a failed card in 10 years 
of pro use, though I've seen a few temporarily deranged ones that could 
not be recovered via USB because the PC could not recognise the card as a 
disk due to MBR or partition table damage so wouldn't mount it. People 
generally throw them away at that point but I bought an IDE card reader to 
deal with those. IDE makes it possible to use low level DOS tools.

If you can't find a copy of Cardwiper at photorescue.com (I couldn't last 
time I wanted to point someone to it) I don't think there is any 
illegality with me making it available at 
https://dl.dropbox.com/u/6401455/cw103.zip

Be careful with Cardwiper, it will utterly wipe your card. That is all it 
does.

-- 
Regards

Tony Sleep
http://tonysleep.co.uk