5DIII CF vs SD slot performance?

[TrabimanUK]

Hi guys,

I've recently purchased a 5DIII, to get some practice in before my holiday as the 7D2 won't be ready in time. I was wondering what the performance difference was when shooting CF vs SD, what with the dual slots.

I've got some OK speed (266x and 600x) CF cards and some OK speed SD cards (30mb/s and 45mb/s). My reason for asking is that I have a raft of the SD cards, accrued over the last few years for shooting twin 60D, and not many CFs. I was wondering if when on safari I ran out of CF space, I could switch to SD, but how much fps would I loose?

I'll be mainly using the 5DIII for lanscape and closeup animals, but might want to set it to rapid fire, or even video if anything interesting happens.

Many thanks,

Grant

 

[StudentOfLight]

The 5D Mark-III will shoot at 6fps (regardless of whether you SD or CF) until it's buffer fills then it will shoot as fast as buffer space will empty. Both scenarios will be painfully slow compared to the maximum of 6fps.

Attached is a table of file sizes based on average exposure and ISO setting. It can help you estimate fps when the camera's buffer is full. e.g. If your individual burst images are approx 30MB and your card's write speed is 60MB/s then you will get about 2fps.

Note: SD card manufacturers sometimes quote max read speed on their packaging, not max write speed. So read the fine print when buying cards.

Hope that helps. Best regards.

 

[mrsfotografie]

I have a set of Sandisk SD Ultra 16GB Class 10 that I use for extra capacity when on holiday. During regular shooting I notice no performance impact (but I shoot low speed burst only). When reading out the data or reviewing photo's on the camera, the SD's are noticeably slower than for instance my Sandisk 16Gb Ultra CF card.
I won't hesitate to use the SD slot for this purpose again, but normally I prefer the CF slot. Also because the CF cards are larger and more difficult to physically loose.

 

[DRR]

Also know that if you use both - let's say, a 16GB fast CF card, and a 16GB slowish SD card, the camera will default to the speed of the SD card.

Use fast CF whenever possible, I would avoid shooting on SD unless absolutely necessary.

 

[JorritJ]

The CF slot is significantly faster than the SD slot. Most new and expensive SD cards are significantly faster than the 5DmkIII's slot will allow writing to it.

You don't notice this all that much unless you are burst shooting. I just tested this for you, using M, 1/250, F/4.0, ISO 100, pre-focused. In a 30 second run, using my 1000x Lexar Professional CF card, 82 shots were recorded. Using a 95mb/s Sandisk Extreme Pro card, 27 images were recorded.

The CF card clears the camera's buffer much faster, and thus allows you take pictures more than three times as fast as an SD card. You could easily run the same test with your own cards, though they are different speeds, it is quite likely your CF cards will be faster. Note that the ratings on the cards are generally read speed, not write speed, so you actually need to test them instead of looking at the numbers.

FYI, it appears the SD card slot is limited to a speed of 133x, or +- 20mb/s.

Personally, unless I know I have to do heavy burst shooting, I have both CF and SD cards present in my 5DmkIII, and capture to both. Yes, it is slightly slower, but nothing is as slow as a card malfunction requiring you to re-do the shoot (or wedding, or holiday, etc)

 

[fotonunta]

CF is better we all now, Sd card are slower.
_________________________________________________________

Foto Nunta Brasov | Fotograf Nunta | Foto video nunta

 

[TrabimanUK]

Hi guys,

thanks for confirming that- I thought that there was some issue with maximum speed of the SD slot. I only intend to use the SD cards if I run out of space on the CFs, so unlikely to run with both cards in the body at the same time.

Thank again,

Grant

 

[GMCPhotographics]

The CF slot is significantly faster than the SD slot. Most new and expensive SD cards are significantly faster than the 5DmkIII's slot will allow writing to it.

You don't notice this all that much unless you are burst shooting. I just tested this for you, using M, 1/250, F/4.0, ISO 100, pre-focused. In a 30 second run, using my 1000x Lexar Professional CF card, 82 shots were recorded. Using a 95mb/s Sandisk Extreme Pro card, 27 images were recorded.

The CF card clears the camera's buffer much faster, and thus allows you take pictures more than three times as fast as an SD card. You could easily run the same test with your own cards, though they are different speeds, it is quite likely your CF cards will be faster. Note that the ratings on the cards are generally read speed, not write speed, so you actually need to test them instead of looking at the numbers.

FYI, it appears the SD card slot is limited to a speed of 133x, or +- 20mb/s.

Personally, unless I know I have to do heavy burst shooting, I have both CF and SD cards present in my 5DmkIII, and capture to both. Yes, it is slightly slower, but nothing is as slow as a card malfunction requiring you to re-do the shoot (or wedding, or holiday, etc)

Yep, with my cards, I get only 5-6 bursts out of the SD card and I get about 10-12 from the CF card. Interestingly, if I have the Sd card slot enabled (regarlessly of having a card in there) I get the lower buffer / card write times. So when I need to shoot fast and long, I take out the SD card and use the Q button to write to the CF card only.

 

[JorritJ]

Yep, with my cards, I get only 5-6 bursts out of the SD card and I get about 10-12 from the CF card. Interestingly, if I have the Sd card slot enabled (regarlessly of having a card in there) I get the lower buffer / card write times. So when I need to shoot fast and long, I take out the SD card and use the Q button to write to the CF card only.

That's odd, I have noticed no such issue. My settings are set to record to both, and when either CF or SD isn't present, it'll give a warning when you turn on the camera, but I don't notice it negatively effecting speed.

 

[GMCPhotographics]

Yep, with my cards, I get only 5-6 bursts out of the SD card and I get about 10-12 from the CF card. Interestingly, if I have the Sd card slot enabled (regarlessly of having a card in there) I get the lower buffer / card write times. So when I need to shoot fast and long, I take out the SD card and use the Q button to write to the CF card only.

That's odd, I have noticed no such issue. My settings are set to record to both, and when either CF or SD isn't present, it'll give a warning when you turn on the camera, but I don't notice it negatively effecting speed.

It's not the speed, it's the buffer capacity it effects. With the right setting, the Cf card can shoot, buffer and write which frees up more shooting time until the write speed craps out and the buffer fills. With the SD card (raw to CF and Jpeg to CD) the card can't write that fast and the buffer fills up very fast which then stops the shooting.

 

[SwampYankee]

actively using an SD card will significantly slow down the 5DIII when the buffer is full. If you don't shoot very fast, no problem. If you do, consider using just a CF card. It's not just sports. I was shooting dancers recently and had the camera writing to both cards and I missed shots because of the SD card. What I do now is keep the SD card in, but set the camera to only write to it once the CF card is full. You have a great camera there. Treat yourself to the fastest CD card available. Depends on what you shoot but an ultra fast 16GB cards will easily cover a whole day of shooting. Buy 2 and keep one as a spare. you can always buy bigger cards but I prefer many smaller ones (not that 16 GB is small) to one really big one. Buy a 32 GB SD card (they are cheap) and put it in and set the camera to switch to the 2nd card only when the first card is full

 

[jeffreyd00]

Here is my advice if you are taking this on holiday. Write to both cards at the same time. Unless you are shooting 10-12 consecutive frames you won't notice the performance hit BUT the real reason to write to both is you have an instant backup. Instant, as in no fuss, no extra time lost while enjoying your holiday.

Just keep the cards in a separate place when the camera is not in your hands. If on a plane, train etc. keep the cards separate. I have had whole days lost due to stolen equipment, if only I had dual slots at that time my troubles would have been only lost gear and not lost gear and irreplaceable images.

Jeffrey

 

[Mt Spokane Photography]

The issue with SD card speeds is that the 5D MK III does not support UHS-1, and most new cards base their speed ratings on UHS-1, which has a bus that it 2X faster. Cut those speeds in half.

The big issue that many are fooled by is that SD card speeds are based on a new totally blank card. As long as the cells in the card are blank, the camera does not have to do the slow block erase function before it can write to them.

In the real world, we use our SD cards, and depending on the size, they get filled with data sooner or later. This coupled with the belief that formatting in camera somehow blanks the card seems to be missed. There are two types of in camera formatting for SD cards, regular formatting which just updates the fat tables to show that files are available to write over (SLOW). The second type, called low level format, actually erases the card and returns it to full speed. I wonder how many use this function more than once. Its very slow to do a low level format of a large card.

So, with a used SD card that has been formatted in camera, the 5D MK III will achieve somewhere between 5 and 10 MB/sec, no matter what that label says, be it 60MB/sec or 100, its going to be 10MB/sec or less.

Once Canon starts supporting UHS-1, the speeds will double, but... that means 10-20MB/sec once you are in the mode of writing over used memory cells.

CF cards don't have that issue.