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Archive 2013 · Dual Slot Scenarios

  
 
msalvetti
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p.2 #1 · p.2 #1 · Dual Slot Scenarios


I don't think the 5DMKIII can take advantage of the UHS-1 (ultra high speed) SD cards, which were not available in 2012 when RG last did that table. According to Canon, you can use those cards, but you will only be able to write at Class 10 speeds. Which I think is about 20 mb/s. See here:
http://www.canon-europe.com/Support/Consumer_Products/products/cameras/Digital_SLR/EOS_5D_Mark_III.aspx?faqtcmuri=tcm:13-1021162&page=1&type=faq

The 1DMkIV is the same.

I thought the 5DMkIII had a quirk - if you shoot RAW to CF and jpg to SD, then theoretically shouldn't run into trouble with the buffer - the fast CF card deals with the large RAWs, and the slower SD takes the much smaller jpg's. But I thought I read that the MkIII defaults to the speed of the slower card for both slots when writing simultaneously, so the faster CF card can be crippled by the slower SD. Or maybe it's because the camera has to process two images, one RAW and then a conversion to jpg?

Mark



Oct 07, 2013 at 07:19 PM
stanj
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p.2 #2 · p.2 #2 · Dual Slot Scenarios


EB-1 wrote:
SanDisk Extreme Pro 95MB/s 64GB Actual Capacity: 60906MB


That's the one I'm using. My point is not whether its write or read speed is 2x or 4x slower in a USB3 card reader; my point is that in a real life scenario, machine gunning the camera and waiting until I hit the buffer, the CF card is only 2x as deep (actually 1.7x as deep) and not 4x as deep as you mentioned. Again, in real life when in the field I don't measure the card speed by MB/s but rather in time it takes to hit the buffer. I will also submit that the numbers posted are incorrect as my math, as well as card reader measurements, paint a different picture.

Sorry if my numeric comparison was incorrect. I stand by my real life time-to-buffer measurements, which is what I care about.



Oct 08, 2013 at 11:39 AM
Ian.Dobinson
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p.2 #3 · p.2 #3 · Dual Slot Scenarios


stanj wrote:
Again, in real life when in the field I don't measure the card speed by MB/s but rather in time it takes to hit the buffer..


+1 Stan

in real life i think its better to think of Buffer in terms of time rather than frames .





Oct 08, 2013 at 11:46 AM
OntheRez
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p.2 #4 · p.2 #4 · Dual Slot Scenarios


On my 1DIV, I shoot RAW to the CF card and the emergency backup is jpeg to the SD card. I've not found this to have a real world effect on how fast the buffer fills. Shooting RAW with just the CF card isn't significantly different than shooting RAW to the CF and jpeg to the SD. Both cards are latest model speeds. I'd suspect that trying to write RAW to both cards would be slower. One of the attractions of the 1Dx is that Canon finally made both slots CF. Never understood why the difference earlier.

Robert



Oct 08, 2013 at 12:57 PM
RichFisher
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p.2 #5 · p.2 #5 · Dual Slot Scenarios


stanj wrote:
It is certainly no UDMA7 1000x speed, but using a SanDisk Pro 95MB/s SDXC card, it's not that far behind either.


I tend to use the 2nd slot as backup/overflow. Though the SD is slower I can use for a brief period of time until I can switch CF cards.



Oct 08, 2013 at 07:27 PM
Erik_J
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p.2 #6 · p.2 #6 · Dual Slot Scenarios


Ian.Dobinson wrote:
+1 Stan

in real life i think its better to think of Buffer in terms of time rather than frames .



But when you do that you will get different times depending on what shutter speed you use.



Oct 09, 2013 at 12:56 AM
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