Hi Pentaxian friends,We have come a long way with memory cards. In the beginning, Compact Flash (CF) were the king of the digital memory medium. They are still used today in most Nikon and Canon cameras, but gradually, they are being replaced by the Secured Digital High Capacity (SDHC) memory cards. Why not? SDHC cards are much smaller and they have about the same capacity of the CF cards. Isn't going smaller, with the same results, what it's all about? Some DSLR cameras have the ability to use CF and SDHC cards. Why not make slots for two SDHC cards? Maybe one for RAW and the other for JPEG, recording simultaneously. That would solve the RAW or JPEG dilemma. I anticipate that one day, the memory cards will be cheap enough that we will buy them by the dozens, and instead or worrying about our hard drives capacity for keeping our images, we'll just keep the memory cards and file them in special containers with labels. It will be like keeping negatives or slides in the film era. I think that it would save a lot of problems. You know, you can lock these memory cards so that they cannot be written over.
Here is an excerpt from Sandisk Website:
Here is an excerpt from Sandisk Website:
Which way to turn?
In a few short years since the launch of the first flash memory cards, the number available for digital cameras and other devices has exploded with a number of different formats and speeds of memory card. It's no wonder the average person is totally baffled by this plethora of memory cards.For most people speed is not important, but there are occasions where having a fast card will be preferable.
In a few short years since the launch of the first flash memory cards, the number available for digital cameras and other devices has exploded with a number of different formats and speeds of memory card. It's no wonder the average person is totally baffled by this plethora of memory cards.For most people speed is not important, but there are occasions where having a fast card will be preferable.
What is Card Speed?
Card speed is quantified by stating the read and write speeds in megabytes per second (MB/sec). This gives an indication of how quickly data can be written and read from a card. These figures, given by the manufacturer in their specifications, are to be considered as guidance only, as speed and performance will vary with almost every combination of card and device.
Card speed is quantified by stating the read and write speeds in megabytes per second (MB/sec). This gives an indication of how quickly data can be written and read from a card. These figures, given by the manufacturer in their specifications, are to be considered as guidance only, as speed and performance will vary with almost every combination of card and device.
What difference does it make?
So, if a photographer using a digital camera wants to take a string of photographs in quick succession, the memory card must be able to accept the pictures quickly (high write speed) in order to keep up with the camera. With a slow write speed card, the camera will pause while the card accepts the data, slowing down the rate at which photographs can be taken. As the resolution, or pixel rate, of new cameras continues to rise, the time taken to write a file to a memory card will increase. While this may only involve a wait of a second or two, it may be enough to make you miss that all important picture.
When photographs were recorded onto film, each picture was precious. With digital photography, you can take as many pictures as you like at no cost, deleting those, which didn’t work out, or were blurred. Large capacity cards are capable of accepting several hundred pictures. At some point these have to be transferred onto your PC, and that might take quite a while. OK, so we’re talking just a few minutes – not a big deal. However, a professional photographer will be doing this time after time. A memory card with a high read speed will help to reduce this time considerably.
Different speed ratings
Memory card manufacturers use different ways to state read and write speeds. Some use the ‘times’ rating such as 12X or 20X, just as the speeds of recordable CDs or DVDs are measured. Others state these speeds in megabytes per second. Some quote speed as a classification. All very confusing.
This chart shows the relationship between speeds:
8X = 1.2 Mb/sec
12X = 1.8 Mb/sec
20X = 3.0 Mb/sec
25X = 3.8 Mb/sec
30X = 4.5 Mb/sec
40X = 6.0 Mb/sec
60X = 9.0 Mb/sec
66X = 10.0 Mb/sec
80X = 12.0 Mb/sec
90X = 15.0 Mb/sec
133X = 20.0 Mb/sec
200X = 30.0 Mb/sec
Secure digital (SD and SDHC) cards often have their speed quoted as a classification:
Class 2Cards have a minimum sustained write speed of about 2 Mb/sec
Class 4Cards have a minimum sustained write speed of about 4 Mb/sec
Class 6Cards have a minimum sustained write speed of about 6 Mb/sec
As a generalization, it is possible to re-classify card speeds as follows:
Normal use or standard speed – 3Mb/sec (20X) or slower
Medium speed – up to 6Mb/sec (40X)
High speed, professional grade – up to 20Mb/sec (133X)
Extra high speed, high-end professional grade – over 20Mb/sec (133X)
The speed of card required depends upon its intended use, and it’s difficult to say which would be best. Obviously, the higher the speed, the higher the cost, so a happy medium should be found.
Low resolution and occasional-use cameras, satellite navigation devices, digital picture frames, games consoles (Wii, PSP, etc.) will perform adequately with normal, everyday cards.Professional photographers using expensive and specialized equipment will benefit from high speed cards, as will those with the latest video equipment. Most other users, with high resolution and digital SLR cameras, video equipment, mobile phones, PDAs and mp3 players, should find medium range memory cards sufficient for most circumstances. Those using high speed cards in equipment that has been on the market for a while may not notice any difference in performance, and those who need a number of memory cards in their work may find that they can mix and match performances depending on the task at hand. There are memory cards currently available with read and write speeds of 60Mb/sec. These are so fast that they out perform the USB connections when transferring data to PCs and need Firewire enabled equipment.
I recently purchased a Sandisk Ultra II 8GB SDHC card with a read and write speed of 15Mb/sec. The price? $39.00 at Costco. Looking at a Shutterbug magazine dated October 2006, a Sandisk standard 2GB SD Class 2 card (read and write speed of 2Mb/sec) was selling for $74.95 at Adorama. You do the math!
So, if a photographer using a digital camera wants to take a string of photographs in quick succession, the memory card must be able to accept the pictures quickly (high write speed) in order to keep up with the camera. With a slow write speed card, the camera will pause while the card accepts the data, slowing down the rate at which photographs can be taken. As the resolution, or pixel rate, of new cameras continues to rise, the time taken to write a file to a memory card will increase. While this may only involve a wait of a second or two, it may be enough to make you miss that all important picture.
When photographs were recorded onto film, each picture was precious. With digital photography, you can take as many pictures as you like at no cost, deleting those, which didn’t work out, or were blurred. Large capacity cards are capable of accepting several hundred pictures. At some point these have to be transferred onto your PC, and that might take quite a while. OK, so we’re talking just a few minutes – not a big deal. However, a professional photographer will be doing this time after time. A memory card with a high read speed will help to reduce this time considerably.
Different speed ratings
Memory card manufacturers use different ways to state read and write speeds. Some use the ‘times’ rating such as 12X or 20X, just as the speeds of recordable CDs or DVDs are measured. Others state these speeds in megabytes per second. Some quote speed as a classification. All very confusing.
This chart shows the relationship between speeds:
8X = 1.2 Mb/sec
12X = 1.8 Mb/sec
20X = 3.0 Mb/sec
25X = 3.8 Mb/sec
30X = 4.5 Mb/sec
40X = 6.0 Mb/sec
60X = 9.0 Mb/sec
66X = 10.0 Mb/sec
80X = 12.0 Mb/sec
90X = 15.0 Mb/sec
133X = 20.0 Mb/sec
200X = 30.0 Mb/sec
Secure digital (SD and SDHC) cards often have their speed quoted as a classification:
Class 2Cards have a minimum sustained write speed of about 2 Mb/sec
Class 4Cards have a minimum sustained write speed of about 4 Mb/sec
Class 6Cards have a minimum sustained write speed of about 6 Mb/sec
As a generalization, it is possible to re-classify card speeds as follows:
Normal use or standard speed – 3Mb/sec (20X) or slower
Medium speed – up to 6Mb/sec (40X)
High speed, professional grade – up to 20Mb/sec (133X)
Extra high speed, high-end professional grade – over 20Mb/sec (133X)
The speed of card required depends upon its intended use, and it’s difficult to say which would be best. Obviously, the higher the speed, the higher the cost, so a happy medium should be found.
Low resolution and occasional-use cameras, satellite navigation devices, digital picture frames, games consoles (Wii, PSP, etc.) will perform adequately with normal, everyday cards.Professional photographers using expensive and specialized equipment will benefit from high speed cards, as will those with the latest video equipment. Most other users, with high resolution and digital SLR cameras, video equipment, mobile phones, PDAs and mp3 players, should find medium range memory cards sufficient for most circumstances. Those using high speed cards in equipment that has been on the market for a while may not notice any difference in performance, and those who need a number of memory cards in their work may find that they can mix and match performances depending on the task at hand. There are memory cards currently available with read and write speeds of 60Mb/sec. These are so fast that they out perform the USB connections when transferring data to PCs and need Firewire enabled equipment.
I recently purchased a Sandisk Ultra II 8GB SDHC card with a read and write speed of 15Mb/sec. The price? $39.00 at Costco. Looking at a Shutterbug magazine dated October 2006, a Sandisk standard 2GB SD Class 2 card (read and write speed of 2Mb/sec) was selling for $74.95 at Adorama. You do the math!
Available now...SanDisk Extreme III SDHC memory card offers turbocharged read/write speeds of up to 30MB/second, top-flight security (including a cool write protection feature that never overwrites files unless authorized), and a surprisingly high capacity in such a small size. Digital pictures now have a place they can call home.We are getting close to buying the SDHC cards by the dozen, don't you think?
Thank you for reading,
Yvon Bourque
1 comment:
The 4GB Class 6 (6MB/s) card I got with my K10D 1 year ago died recently. I remember paying $45 for it (and it came with a small card reader). To replace it I bought *2* 4GB 133x (20MB/s) for $12, including S&H.
The second thing I noticed (the first was the price) was the speed. I could tell straight away that the K10D was writing and reading quicker, much quicker. I'm not a 10FPS shooter, but I appreciate having almost instant playback after taking a shot now.
I'm never going back to slow cards ever again.
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