5d3 CF and SD slots

[robdubbleu]

Hello folks, I'm the proud new owner of a Canon-refurbed 5d3. I'm wondering if the problem of slow CF speeds when a SD card present is still an issue with the latest firmware. I googled quite a bit but the most recent discussions I found were circa 2013.

I want to use an SD card as a backup (and mostly because I'm lazy and want to be able to just insert the SD card into my Macbook Pro instead of using a card reader). However, if it's still going to dramatically limit the CF slot, I might not do it.

Thanks!

 

[tpatana]

Someone said it's been fixed (as in it doesn't slow down if you don't use SD), but I haven't seen official confirmation, and I'm paranoid enough that I use CF only, not even SD present inside. If you use both CF+SD, then it still slows down I believe, that's HW feature.

 

[Mt Spokane Photography]

A SD Card does not slow the camera down until the buffer is full and the SD card tales longer to finish writing.


It is pretty much a non issue for me, since I have never filled my buffer.

 

[FTb-n]

I always have cards in both slots and I've not seen an issue with the SD card's presence affecting the CF card's performance. Occasionally, I'll write RAW to both cards for an important event. If I fill the buffer in burst mode, then I'll see a slow down, but this isn't common.

You can always test this. Shoot RAW to the CF card, burst until the buffer fills with no SD card, then try again with an SD card.

 

[Bennymiata]

I always have both slots full, but I only use the fastest Lexar cards.
I've never noticed any slow down with the SD card as long as it's a fast card.

 

[Mt Spokane Photography]

Hello folks, I'm the proud new owner of a Canon-refurbed 5d3. I'm wondering if the problem of slow CF speeds when a SD card present is still an issue with the latest firmware. I googled quite a bit but the most recent discussions I found were circa 2013.

Thanks!

The issue is not firmware based, but hardware based. The writing to SD cards is slower than newer models that have the faster bus speeds needed for UHS-1 cards. No amount of firmware changes can double the bus speeds, they are hardware based. Thus, when the buffer is filled and the camera slows down to wait for a image to write to the cards, the slowest card may be a limiting factor. If you are writing RAW files to both cards, you can see it. However, many of us write the much smaller jpeg files to the SD card, since they are smaller files, they complete writing in less time and this compensates for the slower writing speed, and its a non issue.

 

[cervantes]

The issue is not firmware based, but hardware based. The writing to SD cards is slower than newer models that have the faster bus speeds needed for UHS-1 cards. No amount of firmware changes can double the bus speeds, they are hardware based. Thus, when the buffer is filled and the camera slows down to wait for a image to write to the cards, the slowest card may be a limiting factor. If you are writing RAW files to both cards, you can see it. However, many of us write the much smaller jpeg files to the SD card, since they are smaller files, they complete writing in less time and this compensates for the slower writing speed, and its a non issue.

You didn't understand the question. The question was if the camera will be slower if a SD card is inserted but not in use - images are only written to the CF-card. This was (is?) a known issue of the 5D3 and can indeed be fixed by a firmware update.

 

[K]

As others have mentioned, the 5D3 is not UHS compatible for SD. That means it cannot write at the speeds at which faster SD cards can accept these days. It uses an older standard.

Therefore, the SD slot is considerably slower than the CF slot (even if you have identical speed CF and SD cards).

For this reason, write speed is capped to the slower slot. It's 1 image at a time. Until all slots are finished writing that one image floating in memory, it can't clear it from the memory buffer.

When there is only a CF card present, the camera does not have to slow down for anything and writes at the maximum possible speed. Which is the maximum speed of the CF card.

Thus, the full-speed continuous buffer is smaller the moment you insert an SD card. Because the camera knows it can only buffer so many images and write so many simultaneously before it slows down based on the slowest slot - which is the SD slot.

It's a hardware issue, and will never be resolved.

Canon included faster SD on the 7D2 and 5DS.