Capacity of 1GB SanDisk Ultra vs 1GB Microdrive

I've just bought a 1GB SanDisk Ultra compact flash card for use with a 10D.
I also have a 1GB microdrive.. It appears that the formatted capacity of the
SanDisk card is about 976MB whereas the formatted capacity of the microdrive
is 1GB. This means that the microdrive holds about 20 more RAW images than
the flash card.I wasn't expecting this difference in capacity. Is the
capacity of the 1GB Ultra OK or is it bad?

Thanks,

Graham.

 

Hi,

Different folks computer differently.
for example 1KB (kilobytes) is actually 1024 bytes in the PC world.
However 1K (One Kilo) is actually 1,000.

So the multiplication factor could be

X * 1000 or X *1024

When you are talking Gigabytes, it can make a difference.

Rosita

 

From: "Graham Russell"

I see the same type thing when comparing my 1 GB Lexar CF with my 1 GB
microdrive. I'm sure there's a good reason ...

Seems to be par for the course. http://www.dpreview.com/articles/mediacompare/
shows actual capacity for a variety of cards and the microdrives are pretty
much the only ones with the full listed capacity.

Bill

 

More fundamentally, the "correct" measurement makes sole use of powers
of 2.
________________________________________________________
Ed Ruf Lifetime AMA# 344007 ()
http://members.cox.net/egruf
See images taken with my CP-990 and 5700 at
http://members.cox.net/egruf-digicam

 

It does, but then so much of a disk is taken up by directories, boot
sectors, FAT tables, etc. that the difference really isn't too significant.

 

The problem is many companies in their advertising use "mega" (which is 2**20
or 1,048,576) when they should use "million" (which is 1,000,000). And they
use kilo (2**10 or 1,024) when they should use thousand. It's a "powers of
two" vs "powers of ten" type thing and companies pick the number that makes
their product look better.

Some of these disks use up a bit of space for boot sectors, etc too. What the
capacity numbers SHOULD say is the actual number of free bytes. At times it's
bordering on fraud and I'm surprised some publicity hound DA hasn't filed a
class action suit demanding the disk and memory guys decide on unambiguous
standards.

Bill
(former digital design engineer)

 

Not too significant?

{ (2^30 - 10^9) / (2^30) } *100 = 6.9%

If the gas station down the street was off this much they'd surely get
fined by your state's weights and measures office.
________________________________________________________
Ed Ruf Lifetime AMA# 344007 ()
http://members.cox.net/egruf
See images taken with my CP-990 and 5700 at
http://members.cox.net/egruf-digicam

 

But a kilometer is 1000 meters, not 1024... Kilo, mega, giga, etc are
all established SI prefixes that translate to even powers of 10, so
companies using mega for 1 million are technically correct. To fix the
problem, the IEC has actually adopted the horribly silly-sounding
kibi/mebi/gibi system. So far, I've NEVER heard anyone utter these
terms in actual speech. At least they're thinking in the right
direction, though. A binary kilobyte, or kibibyte (or KiB -- yes. the
k is capital now), is 2^10 bytes. I would have preferred different
names, but that's life.

As far as memory cards are concerned, I don't mind that I don't get a
full 2^30 bytes (Well, 2^29 for the card I'm using right now). 488MB
is still much larger than the next step down, and that's all I'm
really concerned with. The numbers are pretty much arbitrary, since
I'm not thinking "I need EXACTLY n pictures on this card, or it's
useless!" The difference between 512MB and 512MiB (there, IEC, are you
happy?) is only 5%, and since the size of the pictures I take
fluctuates *anyway*, I don't care that it's slightly less than it
should be, I guess.

Jeff
(current digital design engineer)

 

Cards are formatted too, and there's a certain amount of overhead that
is inherent in all cards. 976 MB sounds about right.