CF card speeds

[jerry12953]

Different manufacturesuse different ways of describing the speed of their cards.

For example I have a Sandisk extreme Plus at 80 Mb/sec, and a Transcend UDMA7 at 1000x.

Is there any way of translating one into the other?

Thanks.

 

[cosmicma]

the X???? speed derives from the CD meaning X 1 speed is 150kbps
so 100x speed means 15mbps , 200x 30mbps etc..

a card stating 80mbps would be around 500x

 

[jerry12953]

OK! Thanks.

I'm sure they do it to confuse us........

 

[cosmicma]

i think it's just marketing
a 600x speed sounds a little more impressive than 90mbps
most people know what 90mbps means but not as many would know what the actual transfer rate 600x really is

 

[jerry12953]

A bit like phone and electric companies make almost impossible to directly compare their rates with other companies rates.....

Any idea what UDMA7 means?

 

[HoppyUK]

Divide by 6.6 to convert to MB/s.

The only figure that really matters is Write speed, that some manufacturers like Lexar don't even quote - how quickly the card can clear the buffer. And that only matters if you shoot repeated long bursts in continuous mode, one after the other in quick succession. But if you test Write speed, don't be surprised if what you get is way below the claimed figure. The number quoted in big letters is always the higher Read speed that is pretty much unimportant.

 

[jerry12953]

Sounds like claimed broadband speeds...........always take with a bucketful of salt.

 

[buckas]

5d3/1dx knock the Raws out at 167mb/s so if you want maximum burst rate then go for sandisk 160mb/s or Lexar 1066x

 

[Gaz J]

There is definitely an advantage to using very fast CF cards on the 5D3 if you are trying to maximise your FPS before slowdown occurs. Average of 7-8 frames on a 160MB/S before frame rate slowdown compared to a 60mB/S card.

 

[hollis_f]

the X???? speed derives from the CD meaning X 1 speed is 150kbps

so 100x speed means 15mbps , 200x 30mbps etc..

a card stating 80mbps would be around 500x

Data transfer speeds is one area where you've got to watch the case of the units. 1x transfer speed is 150kB/s. And 100x means 15 MB/s. The difference between b (for bits) and B (for bytes) is important and real. Transfer rates (especially for netwok speeds) is often quoted in Mb/s - which is 8 times larger than MB/s.

So 15mbps translates as 15 millibits per second - which is 8 billion times slower than 15 megabytes per second.

 

[cosmicma]

Data transfer speeds is one area where you've got to watch the case of the units. 1x transfer speed is 150kB/s. And 100x means 15 MB/s. The difference between b (for bits) and B (for bytes) is important and real. Transfer rates (especially for netwok speeds) is often quoted in Mb/s - which is 8 times larger than MB/s.

So 15mbps translates as 15 millibits per second - which is 8 billion times slower than 15 megabytes per second.

i am aware of that it was just me being lazy with the caps lock