Originally posted by photoptimist Very true. Individual photo deletion has two other problems:
1) Over time, the memory space of the card will become fragmented which will slow it's operation.
2) If the card does suffer from some kind of corruption in the file system, it will be carried over to the next photo session and may cause data loss.
Reformatting gives the card a fresh start.
That is not how SD works. Flash memory does not slow down due to fragmentation or storage space. There are no moving parts to contend with to cause any particular read/write to be any slower than any other. (perhaps an engineer with a digital scope could see a difference, but certainly not by reading/writing from the camera or computer.
Additionally,
Formatting in camera or on computer or deleting of files individually (whether on camera or on computer) makes no difference what-so-ever.
The digital format and card-based OS (the actual calls to read/write) are OS agnostic and of a "standard". If the standard was not followed, you'd have a whole host of issues quite immediately. So much so that the manufacturer would have warnings all over the packaging warning people to not use them in their desktop machines. This concept of operating in-cvamera vs on-compuret is ludicrous.
The action of deleting of single files is not going to cause a problem. Regardless of whether it is from camera or from computer.
If the card is bad, you may have issues... but it won't be simply due to any single action behaving differently than any other.
Formatting the card to "fix" problems will also not work. SD cards don't work that way. Actual hard drives don't either, but they don't dynamically alter their accessible bits to the degree that flash memory can. i.e. unlike a spinning hard drive, full formatting flash memory beginning to end by computer will actually result in the same blocks being re-written many times, leaving many blocks untouched.
You really need a special program that will force a write to every bit and not allow SD to dynamically alter where your device it looking. Something like this can help. (
https://www.sdcard.org/downloads/formatter_4/) It will do a true end-to-end format and can help shake out bad blocks and allow the card to mark them as unusable. A task that would be extremely difficult or impossible to do with normal use or by formatting in-camera or in-computer.