Format CF card or delete images?

Hello,

I have an EOS 20D.
I use a SanDisk Extreme USB 2.0 card reader to copy images off the SanDisk Extreme III 4GB CF card. I then put the CF card back into the 20D and delete all the images using the camera. This as you know deletes the images but leaves the folders intact (empty). Is it best to delete images or use the format option? Will formatting the CF card delete the current folders and then create a new folder?
Delete or format?


Oh, almost forgot, I have the camera file numbering set to "Continuous". File numbering option "Auto Reset" a better option?

I always format my card after I transfer my images to my computer. Completely wiping the card makes it much less likely that you'll ever get a corrupted file.

I've been wondering this myself. I use a card reader for both types of cards I have, and I usually just open the folder and select the images and drag them to a folder, then delete them off the card on the PC.

I've heard people say "format on the PC", "format in the camera", "never format", "always format", etc.

I still don't know what's "right".

I don't think that there is a right or wrong. All techniques seem to work fine for those using them. I can state what I use and you can draw your own conclusions from that. I always move the pics over from the CF card, back them up, then re-format the card using a full format in PC. It has worked flawlessly for me.

Intresting. I have noticed my new 40d doesnt have a delete all option like my 400D did. So I have been deleting large numbers of files in camera rather than one by one using the erase button (usually when I am experimenting or just goofing off).

I was wondering if this would have any undesired effects if its done alot. Ill have to check back on this thread.

I just got my first SLR, 50D 3 weeks ago.

I don't like the idea of opening the camera door and pulling and inserting my $200 cards every 15 minutes when I do my test shots. I rather just plug the mini-USB cable in the camera instead. No chance of bending my pins inside my camera or wearing/losening the ones out in my card.

After the upload to PC, I format the card in camera options section.

I got use to that.

I rarely take my CF card out; mainly to exchange it with an empty card if I fill one up. I use a USB cord and leave the CF card in the camera. After I am done uploading pics, I format the card in camera.

Delete means the characteristics of the file are deleted from the MAP.
It works exactly in the same way on your PC. You can rescue the files with the appropriate program.

Format erases all the sectors of the MAP (it writes all the sectors) : you cannot retrieve the files.
From time to time, it is good to format the CF : it also check all the sectors.

Take also care not to delete a very big number of files followed by new shots between two 'delete all' or 'format' : when you delete a file, the space is available again only if the size of a new one is smaller or same: as a consequence, it could take time to write on the CF or the file could be corrupted.

Be consistent with you deleting/formatting practise and you will not likely have problems with cards.

I'm of the "format" school of thought.

TITROY wrote in post #7495892
Delete means the characteristics of the file are deleted from the MAP.
It works exactly in the same way on your PC. You can rescue the files with the appropriate program.

Format erases all the sectors of the MAP (it writes all the sectors) : you cannot retrieve the files.
From time to time, it is good to format the CF : it also check all the sectors.

Take also care not to delete a very big number of files followed by new shots between two 'delete all' or 'format' : when you delete a file, the space is available again only if the size of a new one is smaller or same: as a consequence, it could take time to write on the CF or the file could be corrupted.

Most formats are just a quick format, which is done by wiping out the superblocks and creating a new filesystem. If it happens in a matter of seconds, no, it hasn't done any error checking, or any form of actual formatting aside from creating a new filesystem in place of the old one. A full format, which no camera does, and most computers will only do if you specifically ask them to, will write out a 0 to every block in the newly created filesystem, not the entire card, and yes, you'll get any blocks that might be going bad marked. But that's completely unnecessary as the cards do that with regular usage anyway, as I've pointed out below.

Honestly, almost everything you said is incorrect. Error checking on CF cards is done at write time. If there's any issue writing, that block is marked bad and the data is written elsewhere. Unlike a magnetic or optical disc, fragmentation is a non-issue as flash memory does not have any form of seek time, so your last point about possible longer write times is entirely moot.

Lastly, unlike regular write blocks, the superblocks on any storage device remain in the same locations no matter what. Repeated formatting will wear out the locations of the superblocks much more quickly than if you never format the card and just erase images, as those superblocks will not be touched aside from reads to determine the filesystem type. If that location dies, the entire card might as well be useless. Write distribution will occur for the filesystem's FAT entries, inodes, etc. depending on filesystem, but not for the superblocks.

For what it's worth, I am a computer engineer; you can trust me on this.

Side note: I'm baffled that people still use FAT for anything.

Canon recommends formatting in the camera, that's what I usually do. BTW you can "recover" images from a formatted card both in-camera format as well as PC. I have recovered files many many times for people who have through error formatted the wrong card and then started taking photos only to get done with session and find they had formatted wrong card. Lexar and San Disk both sell or give away the software. It is also available from other companies, I have used 3 different programs over the years, they all work.

Just a quick question - How do you "wear out" locations on a flash memory device? I can understand it for magnetic media, but I'm not sure I quite understand how that would work for solid state.

Thalagyrt wrote in post #7495958
Lastly, unlike regular write blocks, the superblocks on any storage device remain in the same locations no matter what. Repeated formatting will wear out the locations of the superblocks much more quickly than if you never format the card and just erase images, as those superblocks will not be touched aside from reads to determine the filesystem type.

Since this is flash, you are going through a controller that translates writes from a logical sector to a physical sector. While a superblock may always be in the same logical sector, repeated writes to this sector will cause it to be rewritten to a new physical sector in the flash. Better controllers will even move static data to evenly wear the flash parts to extend their life.

TITROY wrote in post #7495892
Delete means the characteristics of the file are deleted from the MAP.
It works exactly in the same way on your PC. You can rescue the files with the appropriate program.

Format erases all the sectors of the MAP (it writes all the sectors) : you cannot retrieve the files.
From time to time, it is good to format the CF : it also check all the sectors.

Take also care not to delete a very big number of files followed by new shots between two 'delete all' or 'format' : when you delete a file, the space is available again only if the size of a new one is smaller or same: as a consequence, it could take time to write on the CF or the file could be corrupted.

Actually, you can recover formatted CF cards. I know from personal experience.