Recommeded memory speed for supercompact?

[Shawn Hirn]

If I get a modern super-compact digital camera such as a mid-range Canon
IXUS (US: Canon Powershot) for general use then ...

... what minimum speed of SD memory should I get to avoid delays?

Buy whatever's fastest if you can afford it. Even if your camera doesn't
benefit from the faster memory card, you might benefit in faster
download speed if you put the card in a card reader.

 

[Ron Hunter]

If I get a modern super-compact digital camera such as a mid-range Canon
IXUS (US: Canon Powershot) for general use then ...

... what minimum speed of SD memory should I get to avoid delays?

I see "x133" mentioned a lot on memory adverts. Is x133 fast, slow,
just right for the sort of camera I am thing of?

I would probably get 1GB or 2 GB from this store:
http://www.jacobsdigital.co.uk/index.php?thequery=sd+memory

Probably the 133x speed is much faster than the camera will handle. The
problem is that camera manufacturers don't publish their read/write
speeds, if, indeed, they even measure them. I am sure that the 133x
would be faster than ANY non-DSLR, and probably faster than most DSLR
cameras can read/write. You would still gain some speed when
transferring to the computer, if you use either USB 2.0 Hi-Speed, or
Firewire interfaces, however.

 

[Ron Hunter]

x133 is medium to fast. However, how many shots can the camera take in a
second? If you were looking at an SLR with 2 or more frames per second, then
memory speed starts to become an issue, but if the camera can only shoot 1
frame per second, then memory speed doesn't really matter.

My camera, an older Kodak DX6440 can do 6 frame bursts, in 2.5 seconds.
After that, it requires several seconds to dump that data to the card
as the internal buffer memory is filled. I can see no difference in the
rate at which it writes to a 40x card, and faster ones. That means I
can't take more than 6 pictures in something like 30 seconds, which is a
limitation I have felt only once in the time I have had the camera, so I
don't consider it critical. YMMV.

 

[Ron Hunter]

133x is around 20MB/s write speed.

Surely the limiting factor in the transfer from camera buffer to storage RAM
will be the RAM speed - I would be very disappointed in a new camera if the
buses couldn't handle something faster than 20MB/s. I would expect the
theoretical bus speed to be many times that - maybe even 50 times faster
than that!!

NOT. At least not in practice. Camera processors aren't built to be
the fastest processors, but to do a specific job, with minimal power
drain. The don't come close to the speeds of modern desktop machines
with fast dynamic RAM.

 

[Ron Hunter]

But the camera is made up of these components and the performance of the
camera WILL be as slow as the slowest component. Basically, there is the
image processor, the bus and the flash storage. The image processor can
internally process the image much faster than a flash card can read/write
it. And the bus can handle data transfer at rates many times faster than any
flash card.


My EOS can take 3 frames per second until the buffer is full. In 8Mpixels,
high JPEG mode, it shoots about 14 shots until it has to sit and wait for
the memory card to catch up - you can watch the access light to see this. In
RAW mode, this delay is more obvious. So the image processor and bus are not
the bottlenecks - the card is!

I 'expect' that a compact digital camera will be slightly slower at
processing images, but it is still a dedicated chip and will process images
much faster than any memory card can transfer them.

I don't think it matters how long the image processor takes to deal with the
photo - it will be significantly less time than it takes the card to store
it away - why else have Sandisk been working on faster and faster cards -
the Extreme IV is with us now. I don't know figures, but it can probably
save 30+MB/s, but will still be the bottleneck !!

Sorry, but in the P&S world this just is NOT true. You can verify it
easily. Just go out and buy several cards, and see if it makes any
difference in the shot to shot time for a given camera. Hint, it
doesn't, because the bottleneck is NOT the card, but the interface
between the camera memory, and the card.

 

[Ron Hunter]

So based on the exchange here between Richard and GT, the answer to the
OP (me) is that the memory should be reasonably fast but is not likely
to have to be as much as x133 and something like x66 would most likely
do.

Did I get that about right?

Yes. You can buy two cards, one a bit faster than the other, and test
for yourself. If the faster card doesn't appear faster with your
camera, save your money on the next card(s).

 

[kony]

Sorry, but in the P&S world this just is NOT true. You can verify it
easily. Just go out and buy several cards, and see if it makes any
difference in the shot to shot time for a given camera. Hint, it
doesn't, because the bottleneck is NOT the card, but the interface
between the camera memory, and the card.

Pretty arbitrary assumption, given that cameras get faster
every year.

 

[kony]

NOT. At least not in practice. Camera processors aren't built to be
the fastest processors, but to do a specific job, with minimal power
drain. The don't come close to the speeds of modern desktop machines
with fast dynamic RAM.

Right, but they are built to be mission specific and process
as fast as reasonably possible. That some cameras (now old
designs) can't use fast memory is in no way a proof that
anything newer won't process faster, and historically we
have seen processing speed increase, but so has the
resolution so it offsets this a bit. Since the camera will
also be obsolete before the memory card is worn out, there
is also a reason to think in terms of how fast the next
camera might be, presuming it also uses SD format.

 

[kony]

Probably the 133x speed is much faster than the camera will handle. The
problem is that camera manufacturers don't publish their read/write
speeds, if, indeed, they even measure them. I am sure that the 133x
would be faster than ANY non-DSLR, and probably faster than most DSLR
cameras can read/write. You would still gain some speed when
transferring to the computer, if you use either USB 2.0 Hi-Speed, or
Firewire interfaces, however.

Take a look at this page,
http://www.robgalbraith.com/bins/multi_page.asp?cid=6007-8198
On it you will see a camera with write speeds that do not
exceed the "X" speed of several cards, yet it writes
significantly faster with some of the higher speed cards.
For example the 80X card would have a supposed read speed of
almost 12MB/s, but some tested as 4.3MB/s _writing_ while
otherwise the camera was capable of at least 7.7MB/s

Clearly we cannot say it doesn't matter if the card is
higher speed, rather we have to assume it should be both
spec'd for high read speed but as important, high WRITE
speed which is not the number most prominently displayed in
card advertising.

While we don't know the actual write speed of the camera the
OP intends to use (?), there were clearly cameras on the
market for the past two years, let alone today's models,
that benefit from 100X + speed cards. To put it another
way, suppose it takes 1 second to write a 6MB file. That
does not mean it's 6MB/s, it means a fraction of that second
is spent processing the image and the remainder of that
second it's writing it to the card. The data rate was
higher than 6MB/s during the transfer and if the card was
only capable (and fully utilized at) of 6MB/s, it would slow
the camera down.

 

[Richard Polhill]

Pretty arbitrary assumption, given that cameras get faster
every year.

Still true.

 

[Richard Polhill]

Right, but they are built to be mission specific and process
as fast as reasonably possible. That some cameras (now old
designs) can't use fast memory is in no way a proof that
anything newer won't process faster, and historically we
have seen processing speed increase, but so has the
resolution so it offsets this a bit. Since the camera will
also be obsolete before the memory card is worn out, there
is also a reason to think in terms of how fast the next
camera might be, presuming it also uses SD format.

Just think: how long does it take a powerful desktop PC to convert a RAW
image to JPEG?

Now try to do it using a low-power-consumption and compact processor.

 

[Ron Hunter]

Pretty arbitrary assumption, given that cameras get faster
every year.

They do, but they aren't keeping up with speed increases of the cards.
Only a couple of years ago, a 40x card was fast (and expensive), now
133x cards are average, and they cost about 14 as much/GB.

 

[Ray Fischer]

Just think: how long does it take a powerful desktop PC to convert a RAW
image to JPEG?

Now try to do it using a low-power-consumption and compact processor.

That is not a valid comparison because a task-specific processor
can pretty much always do that one task much faster than any
general-purpose processor.

 

[kony]

Just think: how long does it take a powerful desktop PC to convert a RAW
image to JPEG?

Now try to do it using a low-power-consumption and compact processor.

It is an irrelevant comparison because a camera has a
purpose specific processor. It could, if they intended,
convert to JPEG much faster than a PC using a tiny fraction
of the power because it would be optimized towards that end.

 

[FrankLM]

Sorry, but in the P&S world this just is NOT true. You can verify it
easily. Just go out and buy several cards, and see if it makes any
difference in the shot to shot time for a given camera. Hint, it
doesn't, because the bottleneck is NOT the card, but the interface
between the camera memory, and the card.

Wrong-O, El-Brainiac. I have done just this and discovered that some generic
133x brand cards don't bog-down the continuous high-speed shooting-mode in my
P&S camera. It will go non-stop to the capacity of the card with a fast
write-speed card. Yet, oddly, Transcend 150x 4GB cards do. I get nearly 2x's the
burst shooting speed by using the generic cards which have a faster write-speed
than the Transcends.

However, I have since learned that by formatting a 4GB Transcend card in a
non-standard FAT16, vs. FAT32, format, that it restores the write-speed to
something usable again. The camera handles it just fine.

The bottleneck _IS_ in the cards for many P&S cameras because they're so much
faster than DSLRs these days. Unfortunately you're going by the bottleneck that
exists in all DSLRs as your basis for your information. Faster cards can't help
a DSLR, no high-speed cards can help because their buss speeds are limited to
slower shooting speeds. Higher speeds are needed for the All-In-One cameras that
have to do video too. DSLR models are not concerned with fast storage writing
speed so they don't bother making them faster. They rely on an internal buffer
that they eventually SLOWLY dump to the card when it's necessary or convenient.

 

[Ron Hunter]

It is an irrelevant comparison because a camera has a
purpose specific processor. It could, if they intended,
convert to JPEG much faster than a PC using a tiny fraction
of the power because it would be optimized towards that end.

And they are, often by allowing only a minimal subset of the JPEG
standard, which is why some cameras will not display a file that has
been edited on a computer, and then moved back to the flash card.
I fully expect newer cameras to process faster, and to write the larger
files generated by more pixels to the flash card faster than older ones,
and to support larger capacity cards to handle more files, but the race
is never really even. Currently, the flash card makers are a bit ahead
of the cameras. If the cards aren't faster, then they become the
limiting factor, but currently the cameras usually are.

 

[Ron Hunter]

Wrong-O, El-Brainiac. I have done just this and discovered that some generic
133x brand cards don't bog-down the continuous high-speed shooting-mode in my
P&S camera. It will go non-stop to the capacity of the card with a fast
write-speed card. Yet, oddly, Transcend 150x 4GB cards do. I get nearly 2x's the
burst shooting speed by using the generic cards which have a faster write-speed
than the Transcends.

However, I have since learned that by formatting a 4GB Transcend card in a
non-standard FAT16, vs. FAT32, format, that it restores the write-speed to
something usable again. The camera handles it just fine.

The bottleneck _IS_ in the cards for many P&S cameras because they're so much
faster than DSLRs these days. Unfortunately you're going by the bottleneck that
exists in all DSLRs as your basis for your information. Faster cards can't help
a DSLR, no high-speed cards can help because their buss speeds are limited to
slower shooting speeds. Higher speeds are needed for the All-In-One cameras that
have to do video too. DSLR models are not concerned with fast storage writing
speed so they don't bother making them faster. They rely on an internal buffer
that they eventually SLOWLY dump to the card when it's necessary or convenient.

I think you have that turned around. Most DSLR cameras are faster to
write to a card than most P&S cameras, but have it you way.
The basic fact is that it depends on YOUR camera, and YOUR cards. I
have one card that can't write fast enough to capture video from my P&S
camera. It causes 'flicker' on playback as it skips frames. The newer
cards work just fine. Sometimes it is the card, sometimes it is the
camera.
I have had only one case wherein I had more data captured in the camera
buffer than I could get written to the camera while snapping pictures as
fast as I could go, and had to stop shooting to let the card/camera
catch up. Maybe a faster card would have helped, or maybe not.

 

[GT]

Just think: how long does it take a powerful desktop PC to convert a RAW
image to JPEG?

With an 8MPixel image from a 350d:

Core 2 Duo - around 4 seconds to convert from RAW to JPEG

Canon 350d - 3 frames per second, while shooting other frames at the same
time

 

[GT]

Wrong-O, El-Brainiac. I have done just this and discovered that some
generic
133x brand cards don't bog-down the continuous high-speed shooting-mode in
my
P&S camera. It will go non-stop to the capacity of the card with a fast
write-speed card. Yet, oddly, Transcend 150x 4GB cards do. I get nearly
2x's the
burst shooting speed by using the generic cards which have a faster
write-speed
than the Transcends.

However, I have since learned that by formatting a 4GB Transcend card in a
non-standard FAT16, vs. FAT32, format, that it restores the write-speed to
something usable again. The camera handles it just fine.

The bottleneck _IS_ in the cards for many P&S cameras because they're so
much
faster than DSLRs these days. Unfortunately you're going by the bottleneck
that
exists in all DSLRs as your basis for your information. Faster cards can't
help
a DSLR, no high-speed cards can help because their buss speeds are limited
to
slower shooting speeds. Higher speeds are needed for the All-In-One
cameras that
have to do video too. DSLR models are not concerned with fast storage
writing
speed so they don't bother making them faster. They rely on an internal
buffer
that they eventually SLOWLY dump to the card when it's necessary or
convenient.

My Canon 350d DSLR can shoot 3x8Mpixel images per second = 24MB/s. After
around 14 shots, it gets held up by the 'write to card' time and drops to
1-2 frames per second. Does a P&S need to transfer 24MB/s?

 

[FrankLM]

My Canon 350d DSLR can shoot 3x8Mpixel images per second = 24MB/s. After
around 14 shots, it gets held up by the 'write to card' time and drops to
1-2 frames per second. Does a P&S need to transfer 24MB/s?

My P&S camera when saving RAW + Full size JPG comes to 1.1 frames per second,
NON-stop until the card is full. If I had access to faster cards (I'm already
using the fastest available) that would greatly speed up non-stop continuous
shooting. I can verify this by running an internal script (in the camera) to
benchmark test any card in it.The bottleneck IS the cards in the newer and
faster P&S cameras.

You are basing your DSLR speed on the in-camera buffer until it has to pause to
dump it to the card (the pause reducing the overall speed to your slowest norm
when taken into account for total shooting session). After your in-camera buffer
is full then your DSLR becomes much slower than my P&S.

A faster card will not help your DSLR, as others have verified. In a DSLR the
camera is the weakest link for write-to-card speeds, using a faster card doesn't
change their burst shooting rate. In my P&S its burst-rate performance increases
equally to the speed of the card.