CF cards and SD cards on 5dmk3

tomkbucks

tomkbucks

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Ive changed to a 5dmk3 and have an abundance of of decent sd cards, i want to 'double up' for a backup (sending raw to one card and JPG to the other ) is there any reason i should use my CF as my primary 'raw' card over the SD ? as it would save me some money to get more cf cards!
 
yup ive read that before - i do understand it but want to ensure i always have a backup, my shooting does not effect speed really and yes perhaps when im at an airshow or for the confetti shot it may be worth shooting CF only ,
 
If speed isnt that important to you then use both slots. Write speed defaults to the SD card speed which I believe is approx 20MB/S.

If you want max write speed now and again the use CF card only. The 5D3 can make use of the very fastest CF cards and there is a benefit to using for example Sandisk 160MB/s cards if you want to get the absolute max out of the camera.
 
Thanks so is there no disadvantage of using sd as my primary ( I've got loads of 16gb sd cards...) then the jpegs to cf ( I've only got a few 4gb cards... ) this trying to save some money - I'm going to buy one fast cf card for when I need it
 
SD cards are a little slow, just like they were in Canon's '07 generation bodies. Stick with CF unless you shoot landscapes or studio portraits.

Dual is a sensible choice, but it again reduces the bursts. It is so frustrating they had to [intentionally] throw in antiquated technology to make it less good than 1Dx.
 
tomkbucks said:
Thanks so is there no disadvantage of using sd as my primary ( I've got loads of 16gb sd cards...) then the jpegs to cf ( I've only got a few 4gb cards... ) this trying to save some money - I'm going to buy one fast cf card for when I need it
Click to expand...
??
You did read that sd cards are slower?

So your plan is to send more data to the slower sd and less data to the faster cf card.

Based on the fact you had the sd cards first?

Yep! You're on to a winner.
 
well i cant disagree its slower BUT i never shoot high burst - maybe 3 / 4 images , on testing it it seems fine ,i will not dispute that 'just' using cf on a fast card would be more beneficial sometimes - but the key is not all the time. I would be interested to know , if you use SD and CF at the same time (shooting raw + backup jepg) does the speed change depending on which card is primary ? i don't have any really fast CF cards to test this theory so would be interested to know the results
 
I did some tests on this, and I have just done a quick repeat with my new memory cards to confirm.

I disagree with Jeff Cable's assertion that the CD slot is slowed down to match the SD write speed, the numbers don't stack up.

Test... 5D3... Sandisk 120mb/s CF + Sandisk 45mb/s SD
20 frames, 1/125th ISO 100, continuous high, stopwatch started as I hit the shutter

CF Only
Frame rate slowed down after 8 frames
Buffer light went out after 7.7 seconds

CF + SD. RAW to CF and large fine jpeg to SD
Frame rate slowed after 6 frames
Buffer light went out after 9.6 seconds

CF + SD. RAW to CF and small fine jpeg to SD
Frame rate slowed after 8 frames
Buffer light went out after 8.8 seconds

This suggests to me that we are seeing the camera wait until the shot has been written to CF and SD before starting write the next shot. Because it takes longer to write to SD, it appears CF is slowed down but the slot does not get limited to 133x as Jeff Cable stated.
 
RichardtheSane said:
I did some tests on this, and I have just done a quick repeat with my new memory cards to confirm.

I disagree with Jeff Cable's assertion that the CD slot is slowed down to match the SD write speed, the numbers don't stack up.

Test... 5D3... Sandisk 120mb/s CF + Sandisk 45mb/s SD
20 frames, 1/125th ISO 100, continuous high, stopwatch started as I hit the shutter

CF Only
Frame rate slowed down after 8 frames
Buffer light went out after 7.7 seconds

CF + SD. RAW to CF and large fine jpeg to SD
Frame rate slowed after 6 frames
Buffer light went out after 9.6 seconds

CF + SD. RAW to CF and small fine jpeg to SD
Frame rate slowed after 8 frames
Buffer light went out after 8.8 seconds

This suggests to me that we are seeing the camera wait until the shot has been written to CF and SD before starting write the next shot. Because it takes longer to write to SD, it appears CF is slowed down but the slot does not get limited to 133x as Jeff Cable stated.
Click to expand...

Jeff Cable has completely misunderstood -133x etc. relates to the read speed -which is basically irrelevant for high speed shooting- what matters is the write speed.
 
Coyon said:
Jeff Cable has completely misunderstood -133x etc. relates to the read speed -which is basically irrelevant for high speed shooting- what matters is the write speed.
Click to expand...

Yup, agreed.

Although what I was attempting to prove was the CF slot speed didn't get slowed down to match the SD slot.
 
During a wedding I had to resort to sending RAWs to the SD because my CF was full and the camera wouldn't boot with another CF in it :) lesson learned about Magic Lantern.

I was shooting people dancing, in SILENT continuous shutter mode (only 3fps), it was pretty painful and a completely difference experience from using the CF slot. I've even got a 95mb/s SD card.. I didn't realise the port was THAT limited.
 
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Well all very interesting to learn ! seems at different times its worth shooting to different cards, 90% of the time sending RAW to sd and a back up to CF will work fine for me BUT yes things that need speed it seems CF card being raw and small JPEG to sd! thanks chaps :)
 
tomkbucks said:
Well all very interesting to learn ! seems at different times its worth shooting to different cards, 90% of the time sending RAW to sd and a back up to CF will work fine for me BUT yes things that need speed it seems CF card being raw and small JPEG to sd! thanks chaps :)
Click to expand...
 
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