Re: Lost Digi Images - CF Card

Roger wrote:
On Sun, 26 Mar 2006 06:38:00 GMT, "David J Taylor"
<david-taylor@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Roger wrote:
On Sat, 25 Mar 2006 07:38:12 GMT, "David J Taylor"
<david-taylor@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Roger wrote:
[]
4. Format the card regularly don't just keep deleting.

Now this one makes no sense at all.

It makes perfect sense, as it avoids file and directory
fragmentation.

No it does not!

Each extra fragment costs access time, which can result in the card

If you delete all the images there is no fragmentation or slack
space left.

slowing over use without formatting.

it will not slow down because it won't exist.

This sorta sounds like some of the things they'd do at the computer
help desk. The'd give people something to do, but remember that
most of those at the help desks were the beginners.


David

Roger

Roger,

I can see may have to agree to disagree on this.

I don't think we are really in disagreement with maybe the exception
of the way some things are explained.

In terms of simple instructions to users, "format the card in the
camera before use" is easy and what I would recommend to those who
ask.

In more detailed terms, when an OS deletes a file, it doesn't remove
the file data (as you know). Further, the OS /may/ choose not to
overwrite those previously allocated data blocks (to help file
recovery programs),

I don't know of any that do over write those blocks whether it is a
delete or format. I do have programs that will, but a normal format
will not. OTOH it doesn't do that to aid file recovery, although that
is a side effect, they do it because of the time it saves.

To "clean" a one gig CF card by writing ones and zeros alternately to
each bit takes time. To do a reliable wipe I think takes about 10
cycles. To do it on one of my 400 gig drives which takes about 2 to 3
hours for a regular format, takes most of a day or did the only time I
tried it.

and therefore there will be a difference in adding a file to
completely empty CF compared to adding one where some files have
been deleted.

Now, depending on what the OS does, it /may/ be that deleting /all/
files returns the card to a similar state as a "format in the
camera". In which case I have no disagreement with you. However,
it depends on the exact OS behaviour, and there are many different
brands and versions of OS in use.

True there is some dependency, but FAT 16, 32, and NTFS are standards
IF something uses FAT 16 is should be able to read and write to a FAT
16 regardless of what OS created it. OTOH that does not mean it can
read the files the other system uses even if they are FAT 16. OTOH I
know of no cameras that use NTFS.

I don't know about Win 95, but 98, 98 SE, ME, and XP should be able to
read and write to any FAT16 camera file. Getting 98 incarnations to
recognize the device might be the bigger problem.

We can't guarantee that "delete all" produces the same card state as

Life comes with no guarantees <:-)), but the odds are very good that
in most cameras (note the two weasel words, odds and most) delete all
and format will return the card to a state that to the user will be
indistinguishable. (OTOH you don't know until you try).
With the Oly and Nikon I can't even tell the difference and with a
full format on either the original images are still there until they
have been over written. The only real difference between format and
delete all in *most* cameras is the pointers that are deleted although
the directory structure should be recreated it will still look the
same and probably exist at the same addresses..

format. Not to mention the FAT12 / FAT16 / FAT32 / NTFS issues! Or
if the OS chooses to put a recycle bin on the card.

With XP you only need remember which format to use. (Although you do
need to know what format the camera is using)<:-))


Therefore, to preclude any OS dependency (or more precisely, to
force the OS to be that in the camera's firmware), I believe it is
best to stick with a simple guideline:

I really don't have a problem with this as you have qualified the
statement.

"format in the camera before use".

And as I said in an earlier post it is far easier to put out a blanket
statement than go to any depth in the explanation of alternatives.
(and in many cases the explanation would be wasted anyway)

I also agree in keeping things simple as the vast majority of the
population of almost any country is not computer savvy. In the US,
computer literate means you know how to turn 'em on, turn 'em off,
load and run a program, and *maybe* connect to the Internet. That is
a long way from being computer savvy. I taught intro to CS when I was
a GA starting out on my masters. We were lucky to get 185 out of 195
students to be able to get that far and these were college students.

We also have to remember that *most* the people who frequent these
groups on average are a long way from being average and probably stand
far more than head and shoulders above the average camera user, but
when you look at some of the questions you know those individuals are
not practicing safe computing, or even reasonable file management.

Now on to how to figure out how to afford a new D200. <:-))
They finally put a manual connection on the camera for the remote. The
only two complaints I have about my D-70 is no useful mirror lockup
for shooting and it uses an IR remote instead of a mechanical or wired
remote. OTOH the IR would be fine if they'd add a sensor to the back
of the camera as well as the front. Still, for long exposures I
prefer a mechanical release as it doesn't eat up batteries.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

David

Roger,

I don't have any problems with what you wrote. There are perhaps a couple
of points I didn't raise:

- while I agree that the OS will not overwrite the space occupied by
deleted data, it does need to keep a pointer to that "free but used"
space, so that when adding a file it doesn't re-use the "deleted" file's
disk space. We know that DOS does this when it can, but I don't know
about camera firmware. From one experience, I suspect at least the Nikon
5700 does.

- one should try and keep the number of writes to a CF to the minimum.
Does deleting a thousand pictures or reformatting the card result in fewer
writes?

D200 - get a magazine to commission something, or review the camera?

73,
David


.

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