|
The evolution of
memory cards
In the early years of digital photography
(2000-2002), there were many memory card
formats, and cards capacity was measured in
MB, with speeds of few hundreds of kb per
second. With time, many format have
disappeared, and nowadays CF and SD are the
standards. The evolution has brought lower
prices, much bigger capacities and higher
speeds, and nowadays the memory cards have
reached 128 GB of size and speed of 100
MB/s.
Compact Flash are bigger than SD and for
years they have remained physically
unchanged; in 2009 it has been announced a
new standard, the CFast, that is an
evolution of CF: CFast is based on the
Serial ATA bus, rather than the Parallel
ATA/IDE bus of Compact Flash, and it allows
to reach a max speed of 300 MB/s (the
theoretical maximum for CF is 133 MB/s).
Nowadays there are not yet CFast cards on
the market, nor CFast compatible cameras.
Secure Digital cards have had two great
evolutions; in 2006 they have evolved in
SDHC (that are currently the standard and
reach a capacity of 32 GB), and in 2009 the
SDXC format has been announced. SDXC has a
theoretical max capacity of 2 TB and speed
of 300 MB/s; the first cameras compatible
with SDXC has been announced by Canon and
other manufacturers in January 2010. Toshiba
and Panasonic have recently announced their
first SDXC cars with a capacity of 64 GB and
speed of 35 MB/s (233x); the price for these
cards is pretty high ($600), but I expect to
see lower prices as soon as the SDXC will
become more mainstream.
Size and speed
When you chose a memory card,
there are two things to evaluate: size and
speed. Usually you can not choose between SD
and CF, because the majority of cameras
support only one of these formats, so you
have to use the format supported by your
camera. If you have one of the few cameras
that support both (e.g. Canon 1D Mark IV,
Nikon D300s), I recommend the CF if you want
speed, while the SD may be a good choice if
you have other cameras that support only
this format, or if you want a card that can
be read directly by your computer, without
using an external card reader (the majority
of laptops and some desktops have a SD card
reader).
Size depends by the camera you use
and by your current needs. As generic
guideline, for a trip with plenty of photo
opportunities (for example a Safari) I
estimate a maximum of 5-7 GB per day with a
10-12 megapixel camera, or 10-15 GB per day
with a 20-25 mp camera. In other kinds of
trip (trips for landscapes or
macro) I use much less storage because I
don't use the continues shooting and I am
more selective.
Some
photographers prefer to buy many
low-capacity cards instead of a single
high-capacity card, because they fear to
lose all their photos if the card fail. This
is a controversial topic; in my opinion,
having a lot of card just increases the risk
to lose one of them. The CF and SD are very
reliable, and it is very unlikely that they
fails. It is curious to see that many are so
worried about CF/SD cards, then they store
all their photos on the single hard disk of
the computer, a much less reliable support,
without even thinking about back-up copies
in the (likely) possibility that the
computer hard disk fails, due to software
problems, virus or other factors. Anyway;
this is just my opinion, I prefer to use a
couple of large card, but of course everyone is
free to use the card size he prefers! :-)
Speed depends by the kind of
photography you do and by the use of video.
If you do wildlife photography and you use a
lot the continuous shooting, a fast card is
a plus because it allows to empty the buffer
in few seconds. For landscapes and macro, a
fast cards is a waste of money. If you take
HD videos, you need a card with a good write
speed to avoid dropped frames; in this case
I recommend a card that has at least a write
speed of 200x (30 MB/s). A very important
thing to remember is that the actual speed
varies widely depending by the camera - if a
camera has poor write speeds, you can use
even the fastest card of the world, but you
will get slow write speeds.
Frequently Asked
Questions about CF and SD
What does manufacturers speed ratings
mean? every manufacturer give a "x"
rating to the card. For CF and SD cards, an
"x" means 0.15 MB/s, so for example a card
that is rated 133x should be able to write
at 20 MB/s (0.15 x 133). That said, the
actual speed is often lower than the rated
speed, it depends by the camera you use.
How do I know the actual speed of the
camera? You can ask on
JuzaForum to
receiver owners' opinions; other than that,
I recommend to check the
Rob Galbraith CF/SD database (it is not
updated very often but overall it is a good
resource).
What brands do you recommend?
SanDisk and Transcend are my favorites;
other good brands are Lexar, Panasonic,
Pretec. I'd suggest to avoid unknown brands
as they may be less reliable than the
mainstream brands.
What
speed do you really need? You don't need the
fasted card on the market! If you take "action" photos, for
example birds and wildlife, and you use a
lot the continuous shooting, a fast card is
a big help to be always ready to shoot. But
if you take mainly landscape or macro photos
even a slow card is ok! Currently, I use
Transcend 32 GB 133x cards for my 1DsIII:
there are much faster cards, but the Transcend
133x are enough for my necessities, and they
are much cheaper than faster cards.
How much storage space? I recommend to
choose the card size according to your
current necessities...don't think about what
you may need after six months or one year,
think about what you need now. The prices of
memory cards drops quickly, so cards are not
a good investment - what you buy now for
$100 after one year or less will be
available for $50.
Which cards do you
use? I have three Transcend 133x 32 GB
CF ($100). They are not super fast but they
are cheap and they offer huge capacity; that
said, nowadays for few more dollars you can
get the much faster Transcend 400x 32 GB CF
($180). In future I'll replace them with two
Transcend 64GB 400x ($400), but I don't have
immediate necessity so I'll wait some time
until the price of these 64 GB cards come
down :-)
What is the largest card currently
available? Both Pretec and Silicon Power
have a 128 GB CF card, but between the
mainstream cards - those you can find in
every shop - the largest ones are currently
the SanDisk 64 GB Extreme Pro 600x ($ 700)
and the Transcend 64 GB 400x ($ 400).
What is the fastest
card currently available? The SanDisk 64
GB Extreme Pro 600x (90 MB/s) is currently
the fastest card on the market; it costs
$700. (the Pretec 667x may be a bit faster,
but they are very rare)
What about portable HDD (e.g. Epson
P5000)? I consider them a thing of the
past. Nowadays with few high capacity CFs
you can cover an entire trip; memory cards
are more reliable and they do not require
energy. During my trip to Tanzania in 2008,
I met a couple of photographers who has four
portable HDDs...after ten days, two of these
HDD had failed, due to the dusty environment
and to the frequent bumps you get in the
jeep. In years of photography, instead, I
have never had a problem with a flash
memory.
Do you have
comments or questions?
If you have comments or questions about
this article, feel free to ask in the
Juza
Nature Photography Discussion Forum!
|
