CF or SD in 5D III

[Eaglewing]

I do understand the camera writes faster to a CF card but slower to SD card.

Granted the difference, I am interested to know how others make use of the two slots.

Would you use:

• Only CF
• Only SD
• Writing both to CF and SD in RAW
• Write to CF in RAW and SD in Jpeg

Note: I do not have the 5D IIII until I take delivery this weekend.

[TTMartin]

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@Eaglewing wrote:

I do understand the camera writes faster to a CF card but slower to SD card.

Granted the difference, I am interested to know how others make use of the two slots.

Would you use:

• Only CF
• Only SD
• Writing both to CF and SD in RAW
• Write to CF in RAW and SD in Jpeg

Note: I do not have the 5D IIII until I take delivery this weekend.

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While I have a 7D Mk II and not a 5D Mk III, have a card in both slots, but, write only RAWs to the CF slot. I like the slightly larger CF card, and think they are a little more durable to handle. 

[jrhoffman75]

If you write RAW to both cards the slower SD card will control the buffer clearing rate. Writing RAW to CF and JPEG to SD may or may not affect speed, depending on JPEG size. SD card write speed is controlled by camera; high speed SD card won't overcome this.

[RobertTheFat]

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@Eaglewing wrote:

I do understand the camera writes faster to a CF card but slower to SD card.

Granted the difference, I am interested to know how others make use of the two slots.

Would you use:

• Only CF
• Only SD
• Writing both to CF and SD in RAW
• Write to CF in RAW and SD in Jpeg

Note: I do not have the 5D IIII until I take delivery this weekend.

---

One thing to keep in mind that I don't think is well described in the manual: If you have cards in both slots and have set the preference to write to one card until it fills up and then switch to the other, taking the active card out (even, in most cases, with the camera turned off) will reset the preference to the other card. And putting the removed card back in the camera will NOT restore the preference to what it was; you have to reset it manually.

That hideous misfeature is evidently intentional, as it is retained in the 7D Mark II.

[Waddizzle]

"That hideous misfeature is evidently intentional, as it is retained in the 7D Mark II."  

I would agree with that behavior.  The camera would either have to assume that you replaced the same card into the slot, or it would have to go through some elaborate routine in order to determine if the original card has been returned, without modificaitons. 

Without the camera continuously making a backup copy of the card ahead of time, it should not have any way of performing the latter test and determination.  The camera is forced to assume that you have inserted a new and different card, and rely on you to tell it what to do.

[RobertTheFat]

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@Waddizzle wrote:

"That hideous misfeature is evidently intentional, as it is retained in the 7D Mark II."  

I would agree with that behavior.  The camera would either have to assume that you replaced the same card into the slot, or it would have to go through some elaborate routine in order to determine if the original card has been returned, without modificaitons. 

Without the camera continuously making a backup copy of the card ahead of time, it should not have any way of performing the latter test and determination.  The camera is forced to assume that you have inserted a new and different card, and rely on you to tell it what to do.

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I don't follow that reasoning at all. Nothing in the specs promises "a backup copy of the card". Indeed, in the case I cited, the cards are used consecutively, without any image file being written to both cards. So it doesn't make a particle of difference whether the same card or a different card is returned to the original slot.

[Eaglewing]

Gentlemen,

Thank you for your contribution and sharing your views, much appreciated.

Back to my original post, how do you use the two-slots system in the 5D III, granted it has its limitation.

[jrhoffman75]

I have a 1D Mark IV, which has the same card configuration. I write RAW to the CF card and small JPEG to the SD card. I use the JPEGs for quick posting to the site I share travel photos on.

[Eaglewing]

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@jrhoffman75 wrote:

I have a 1D Mark IV, which has the same card configuration. I write RAW to the CF card and small JPEG to the SD card. I use the JPEGs for quick posting to the site I share travel photos on.

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John, this may be a good way for me to start and I shall keep this in mind. Thank you for sharing.

[Waddizzle]

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@RobertTheFat wrote:

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@Waddizzle wrote:

"That hideous misfeature is evidently intentional, as it is retained in the 7D Mark II."  

I would agree with that behavior.  The camera would either have to assume that you replaced the same card into the slot, or it would have to go through some elaborate routine in order to determine if the original card has been returned, without modificaitons. 

Without the camera continuously making a backup copy of the card ahead of time, it should not have any way of performing the latter test and determination.  The camera is forced to assume that you have inserted a new and different card, and rely on you to tell it what to do.

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I don't follow that reasoning at all. Nothing in the specs promises "a backup copy of the card". Indeed, in the case I cited, the cards are used consecutively, without any image file being written to both cards. So it doesn't make a particle of difference whether the same card or a different card is returned to the original slot.

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It shouldn't be too hard to follow.  Camera specifications has nothing to do with it.  In fact, the lack of "a backup copy of the card" in the specificaitons supports my conclusion.  Let me explain it in more detail......

If you remove a card from the camera, and then insert a card back into slot, should the camera assume that you have re-inserted the same card?  No, of course, not, which is why it makes no presumption about the content of the card, and must rely on you [as inconvenient as you find it] to tell it what to do with the fresh card..

Putting enough smarts into the firmware to recognize different cards would only take away memory space from the programming that creates the pictures.  Imagine that all of the computer instructions that run the camera must be written in 144 characters, or less. 

If given the choice between writing code to add bells and whistles [like recognizing re-inserted cards], or writing code to improve performace, which choice do you think they would make?  They would choose to include code that improved performance and force you to tell the camera what to do with a freshly inserted card.