Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion

Started Feb 6, 2012 | Discussions
Burner100
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Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
Feb 6, 2012

Just ordered up a shiny new T3i and started to research memory cards. Turns out that what should have been a simple exercise turned out to be quite a bit more complicated.

The first question to answer is, "why care?". The answer is quite simple, two reasons really, 1) the camera requires at least a Class 6 card running at 6MB/s to record HD video but some folks have reported issues with some cards and not others, a faster card is less likely to hiccup on recording, 2) the speed with which the camera can dump photos from the internal buffer to the memory card is critical when snapping many shots in quick succession - when the buffer fills no more shots can be taken until the buffer empties enough for additional photos to be taken - the faster the memory card, the faster the buffer writes out the photos and the sooner additional photos can be taken.

The confusion occurs because there are new very high speed SD Cards available, such as the Sandisk Extreme Pro line, which can support speeds at 45MB/s and even 95MB/s depending on which card is selected. Importantly, the 45MB/s and the 95MB/s cards leverage a new communication protocol called UHS-1 (ultra high speed 1) but are also backward compatible with the old Class 1-10 rating system. The T3i supports SDXC cards, and is advertised as such, and the SDXC cards have additional capacity exceeding 32GB and also use the exFAT file system to handle the larger size. However, it is not automatically the case that all SDXC cards support UHS-1 (as far as I can tell) as an example, some could just be a Class 10 card. Now, this gets even more complicated because it is apparently also possible to have an SDHC card (32GB or less) which supports UHS-1 but is not considered SDXC. Furthermore, there are two versions of the UHS-1 protocol, one running at a bus speed of 100mhz and running at a bus speed of 208mhz. Each respectively correlating to a maximum write speed of 50MB/s and 104MB/s. Keep in mind that a Class 10 card is rated for minimum throughput of 10MB/s write speeds. Theoretically, a new UHS-1 card could be 5-10x faster than a Class 10 card depending on the actual performance of the Class 10 card and the supported bus speed of the host device interface and the speed of the UHS-1 card itself.

I was unable to find reliable information regarding what protocols and bus speeds the T3i supports so I called Canon. I was told that the camera supports the UHS-1 protocol at the 100mhz bus speed and 50MB/s write throughput. This is a very big deal because even the fastest Class 10 cards only deliver actual throughput of 20-25MB/s from what I was able to determine. Minimally, these new UHS-1 cards should deliver about double the throughput of the prior fastest Class 10 cards, and 5x the throughput of the slowest Class 10 cards. In practice, the new UHS-1 100mhz protocol will not deliver a full 50MB/s write throughput due to overhead in the protocol itself. This is why Sandisk rates their card at 45MB/s write speeds instead.

When I asked about the faster 208mhz bus speeds, I was told that the T3i does not support that speed and so spending the money for the super fast 95MB/s memory cards would likely not offer any meaningful performance gains. Despite having been told this by Canon, I'm still tempted to buy a small one and do some benchmarking to see if there are't any performance gains to be had.

Bottom line - if you want to snap lots of photos fast, like for any kind of action shots, then you will want to buy at least a UHS-1 compatible 45MB/s write speed card.

I hope this helps some of you.

Andrew

Canon EOS 600D (EOS Rebel T3i / EOS Kiss X5)
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Shorthand
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Burner100, Feb 6, 2012

I believe that the T3i maxes out at the speed of a Class 6 card. Anything above that is OK but not able to be used by the camera.

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pedrojoper
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Burner100, Feb 7, 2012

That's really useful for those people who use the Magic Lantern firmware and shoot video at high bitrates. I've no idea what's the fastest protocol my 550D supports, and my most frequently used card is a cheap Trascend class10 card, so the highest bitrate I can reliably use is the stock one. For serious videographers, an UHS-1 should be a welcome improvement!

That said, when shooting bursts the speed limiting factor is not always the card, since the camera shoots faster than it can process. Maybe in RAW an improvement is obvious?

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Burner100
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Shorthand, Feb 7, 2012

Shorthand wrote:

I believe that the T3i maxes out at the speed of a Class 6 card. Anything above that is OK but not able to be used by the camera.

Fortunately, that statement is not valid per my conversation with Canon tech support today. The T3i is able to take advantage of cards rated for speeds up to 45MB/s which should be at least 2x faster than the fastest Class 10 cards and about 4.5x faster than a Class 10 card operating at minimum spec of 10MB/s. It should also be between 7-8x faster than a Class 6 card performing at the specified minimum 6MB/s speed. The manual may state Class 6 as the minimum speed for reliable HD video capture, but that it is most definitely not the fastest card supported by the camera.

Again, I want to be absolutely clear about this, I was able to obtain a definitive answer to this question from Canon tech support by phone today. I would suggest that anyone who is still unsure about this to call Canon tech support directly and verify what I was told. The folks are US based (Virginia I believe) and were extremely helpful and friendly.

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Burner100
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to pedrojoper, Feb 7, 2012

pedrojoper wrote:

That's really useful for those people who use the Magic Lantern firmware and shoot video at high bitrates. I've no idea what's the fastest protocol my 550D supports, and my most frequently used card is a cheap Trascend class10 card, so the highest bitrate I can reliably use is the stock one. For serious videographers, an UHS-1 should be a welcome improvement!

That said, when shooting bursts the speed limiting factor is not always the card, since the camera shoots faster than it can process. Maybe in RAW an improvement is obvious?

I have read about Magic Lantern and it has raised my interest. I'll probably try it out. Not sure how much it might change the bit rates for the HD video though. I know that standard HD uses only a small percentage of the sensor and the total data captured is therefore somewhat less than one might expect. I believe Canon suggests Class 6 cards as a minimum spec for the HD video feature.

With respect to shooting speeds, since I don't have the camera yet it's a little hard for me to comment. My understanding is that the faster cards are indeed especially helpful when shooting RAW or RAW+JPG modes. JPG files are so small to start with that with the fast card, it may be possible to shoot non-stop with no slow downs. Of course, to your point, that assumes the internal processor can keep up. If the processor is the bottle neck, then a faster memory card will not help after a certain point. Looks like I'll have some testing to do :).

I did see a YouTube video of a Nikon 700 where the owner was comparing different cards and with the SanDisk 45MB/s, the speed improvement was significant and easily observable. Here is a link to a video which clearly shows the improvement on the Nikon:

http://www.amazon.com/review/R2729BA3E82UK7?ie=UTF8&videoPreplay=1

It is clear how long it takes the camera to save to the SD card. When they step up to the SanDisk, the performance boost is really noticeable.

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Y0GI
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Burner100, Feb 7, 2012

Another good reason to consider UHS-1 cards is to future-proof your card. It looks like the UHS-1 standard will be the wave of the future and as camera technology advances, more cameras will be able to support it.

When I first bought an SD card for my XSi, I bought class 4, which was the minimum recommendation at that time (2009). When the T2i came out with a minimum class 6 for video, it changed my perspective and my next memory card purchase was class 6. I feel that it is a good idea to buy memory that is faster than you currently need so that you will not be stuck with obsolete memory as you upgrade your camera. Of course, you have to consider cost also. Since it is so new, UHS-1 is pretty pricey right now.
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DanCart
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Burner100, Feb 9, 2012

Brilliant post , its quite interesting that the T3i doesnt support the 208MHz bus speed. I wonder if the 60D supports UHS bus at all ?

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Billson
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Burner100, Feb 21, 2012

Did you call or email support? I emailed Cannon support to ask about the max write speeds of the Rebel T3i, and was sent a copy/paste from a PCWorld article about memory cards. When I asked again for specific information regarding the capabilities of the T3i, I was told "Canon has no published write speeds on any of our DSLR's" and that "The faster the memory you place in the camera the faster the
cameras buffer can write to the card."

The only 'useful' information given to me was "We recommend using memory cards with a Speed Class 6..." and he directed me to the Canon website. I wrote back asking to forward my question along to someone who could answer specifically if the T3i would be able to take advantage of UHS-1 speeds, hoping someone could confirm what you have posted here about the camera supporting UHS at the 100MHz bus speed. Unfortunately I was told there was no one to forward my question to and that UHS was simply untested with the T3i at this time.

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DAVEBUCK
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Billson, May 30, 2012

Having read this forum has made me even more confused. I will be leaving for a 3 week trip to Spain and Morrocco next week and I want to get at least a 32 GB or possibly a 64GB card for my T3i. It seems that the UHS-1 card would be better than the standard class 10 cards.

However, I am confused which cards offer this combination. I was looking at Sandisk Extreme and Lexmark Professional. Would anyone be so kind as to clarify this for me.

Thanks!!

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photonius
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to DAVEBUCK, May 30, 2012

DAVEBUCK wrote:

Having read this forum has made me even more confused. I will be leaving for a 3 week trip to Spain and Morrocco next week and I want to get at least a 32 GB or possibly a 64GB card for my T3i. It seems that the UHS-1 card would be better than the standard class 10 cards.

However, I am confused which cards offer this combination. I was looking at Sandisk Extreme and Lexmark Professional. Would anyone be so kind as to clarify this for me.

Thanks!!

sandisk extreme pro has it all

http://www.microspot.ch/microspot/__HYBRIS__/product/Microspot.ch/0000563011/detail.jsf

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hightechfool
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Re: Rebel T3i SD Card Types and Maximum Speeds, SDHC, SDXC, UHS-1 Discussion
In reply to Burner100, 1 month ago

This is the most thorough information on t3i card-speed I've been able to find on the internet.  Thank you so much!

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