CF or SDHC

Started Mar 21, 2013 | Discussions
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tremorhand Regular Member • Posts: 172
CF or SDHC

Just got the 5D3. Why two different memory card types? Is one better than the other?

Canon EOS 5D Mark III
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RS_RS Senior Member • Posts: 1,765
Re: CF or SDHC

tremorhand wrote:

Just got the 5D3. Why two different memory card types? Is one better than the other?

Yes. CF is faster.

MikeFromMesa Senior Member • Posts: 2,849
Re: CF or SDHC

tremorhand wrote:

Just got the 5D3. Why two different memory card types? Is one better than the other?

There are 2 memory cards so one can be used for backup or so that you can write different types of images to different cards. As to why there are 2 different types of cards (rather than 2 cf or 2 sd cards) I assume that there was some savings for them. 2 cf cards would have made the camera larger and probably more expensive. And 2 sd cards would probably have cost Canon some of their buyers since pro type cameras should have a cf card for the extra write speed. I am just guessing, of course.

As to whether or not one type is better than the other, it depends on what you want to do with them. Given equivalent speed cards a camera can write to the cf card faster since there are more data connections and hence more data paths. A cf card has something like 50 data paths and, with the data written concurrently, 50 paths can pass more data more quickly than the 8 paths for the sd card. Given that, the camera can "recover" from several quick images faster with a cf card. And continuous images will write more quickly with a cf card allowing you to be ready for more continuous images with a cf card rather than an sd card.

However most computers today have an sd card reader built-in so you don't need a special cf card reader for copying images to your computer. However, as with the camera, you can probably copy data from a cf card more quickly than from an sd card.

It depends on what is most important to you. I don't know if any of this helps answer your question.

JLim22 Regular Member • Posts: 495
SDHC cheaper-------nt

No text.

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JLim22 Regular Member • Posts: 495
Rob's test results.

http://www.robgalbraith.com/bins/camera_wb_multi_page.asp?cid=6007-12452

If you need the speed, Lexar 1000 seems to be the fastest.

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Y Hafting
Y Hafting Contributing Member • Posts: 787
Data applies for 5d3 only

JLim22 wrote:

http://www.robgalbraith.com/bins/camera_wb_multi_page.asp?cid=6007-12452

If you need the speed, Lexar 1000 seems to be the fastest.

Note that this is valid data only for the 5D3, since it does not support UHS1 etc.

With my 6D (which does support UHS-1) i get something much closer to the specified 90MB/S for the sandisk extreme pro SD cards. The difference between the trancend (20-ish MB/s ) and the sandisk extreme pro is from 4 or 5 frames to 20-21 before buffer runs full with my 6D.

Now theoretically CF can alwas be made better than SD cards, but in practice the problem is writing data fast to the flash memory.

At the moment the practical difference is within the cameras and not so much in the CF vs SD.

The 5D3 users should use Compact flash for burst-photography, while the SD cards will do for video. For users of newer cameras, the difference is not that great at all.

-Yngve

MikeFromMesa Senior Member • Posts: 2,849
Re: Rob's test results.

JLim22 wrote:

http://www.robgalbraith.com/bins/camera_wb_multi_page.asp?cid=6007-12452

If you need the speed, Lexar 1000 seems to be the fastest.

You should probably ignore the sd card speeds as they pertain to the 5D3. See this:

http://jeffcable.blogspot.com/2012/06/why-you-should-not-put-sd-card-in-your.html

JLim22 Regular Member • Posts: 495
OP said, "Just got the 5D3."

Why should he ignore the sd card results?

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Rexgig0 Senior Member • Posts: 3,235
Re: CF or SDHC

I have been fortunate in that I have never lost data/images from a card, so the back-up factor has not yet been of personal benefit. Even so, saving data to two memory cards is comforting to my mind.

On a practical level, I feel I am less likely to fumble and drop a CF card, than an SD card. On the other hand, CF cards engage pins that can be more-easily bent, though I have been careful, and never have bent any pins. More computers and other devices have a built-in SD card slot, which saves one the trouble of always carrying a CF card reader. I do not normally shoot at extremely high frame rates, so the write speed has not been important for me.

When using my 7D cameras at work, I have re-shot really important evidentiary images with the second camera, on several occasions, as a form of insurance against a corrupted card, or fumbled upload. One reason for me to up-grade to a 5D3 would be to have a full-frame camera's low-light benefits, and dual card slots. (My dual-card camera experience has been with a recently-acquired Canon 1D Mark II N, which is not full-frame.)

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MikeFromMesa Senior Member • Posts: 2,849
Re: OP said, "Just got the 5D3."

JLim22 wrote:

Why should he ignore the sd card results?

The 5D3 contains hardware that limits the sd card speed to 133x. That is, no matter how much faster the sd card may be, it will not work faster than 133x on the 5D3.

Given that the sd speed is limited to 133x on the 5D3 the user should not pay attention to comparison speeds of the sd cards past 133x. They will not work faster than 133x on that camera so paying for an sd card faster than that will have no benefit beyond copying speed to the computer.

tremorhand OP Regular Member • Posts: 172
Re: CF or SDHC

Thanks for replies. I stuck 16 GB CF and SD cards in and have been shooting around. Main reason for question was expense difference as well as availability of two formats. SDs are everywhere in ever increasing capacity and at lower cost than CF.

Like other posters, I don't usually shoot in sufficiently rapid bursts to overwhelm the camera to card write speed.

Also I've never had either CF or SD card become corrupted, physically damaged, or otherwise lose data. (I hope I haven't just jinxed myself).

JLim22 Regular Member • Posts: 495
Only if you actually clicked on the link...

and read a little bit, you would see that Rob's test is also on a 5D3.

So Rob's results would actually show speeds one would expect to see on any 5D3. If you compare the speeds between CF and SDHC, SDHC is quite a bit slower.

And you're right, it doesn't make sense to get a faster SDHC card as 5D3 doesn't support faster speeds.

To the OP, check out the link. It seems like it's pretty accurate.

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MikeFromMesa Senior Member • Posts: 2,849
burst speeds

tremorhand wrote:

Like other posters, I don't usually shoot in sufficiently rapid bursts to overwhelm the camera to card write speed.

I don't know about "other posters" but I sometimes shoot birds in flight and have a custom setting set up to do just that. That means that I do sometimes use burst and sometimes overwhelm the camera's buffer space with images.

If you don't take continuous burst shots, then it is not important. If you do sometimes do so, or think you might, there are some things you should plan to do to compensate for the slow write speeds to the sd cards.

MikeFromMesa Senior Member • Posts: 2,849
Re: Only if you actually clicked on the link...

JLim22 wrote:

and read a little bit, you would see that Rob's test is also on a 5D3.

I did actually click on the link and "read a little bit". In fact I had first seen that post (and looked through it) some time ago when I first bought my 5D3. While it was an interesting comparison it does not indicate why the sd cards are so slow. The link I posted was meant to address that.

So Rob's results would actually show speeds one would expect to see on any 5D3. If you compare the speeds between CF and SDHC, SDHC is quite a bit slower.

No body was questioning that. Given equivalent speed sd and cf cards and equivalent hardware the cf cards should always be faster given the larger number of data paths for transfer.

And you're right, it doesn't make sense to get a faster SDHC card as 5D3 doesn't support faster speeds.

That is all I was trying to say.

To the OP, check out the link. It seems like it's pretty accurate.

mjack101 Regular Member • Posts: 108
Re: CF or SDHC

When I first got my 5diii I put both a CF and an SD card in with the SD card set to write only when the CF card is full i.e. no simultaneous writing. The SD card has never been used.

To utilize the 6fps to its max then a CF card is a must.

The article linked above which talks about write speed to the CF card when an SD card is in the slot is a little misleading although it is corrected in the comments section. Unless the camera is set to write to both cards at the same time then there is no effect on the CF card write speed of merely having an SD card in the slot as well.

MikeFromMesa Senior Member • Posts: 2,849
Re: CF or SDHC

mjack101 wrote:

When I first got my 5diii I put both a CF and an SD card in with the SD card set to write only when the CF card is full i.e. no simultaneous writing. The SD card has never been used.

To utilize the 6fps to its max then a CF card is a must.

The article linked above which talks about write speed to the CF card when an SD card is in the slot is a little misleading although it is corrected in the comments section. Unless the camera is set to write to both cards at the same time then there is no effect on the CF card write speed of merely having an SD card in the slot as well.

Granted. The slowdown is only present when the sd card is written to. There are many ways to configure use of the cards and there is often not enough information available to people setting their cameras up to know what the full results of their choices will be.

1) Use of the second card for "roll-over" (that is, write when the first card is full). This will not have any ill effect on the write speed as long as the sd card is not being used. Further, the burst speed and capacity of the camera will not be affected by the setup. It does not, however, really provide any protection if your primary card fails and thus I don't use it.

2) Use of the second card to make copies of what is being written to the first card (the way it is setup on my camera). This will slow down the write time to the flash memory as the sd card writing will take longer than the cf card, but it will not adversely affect the burst capacity of the camera.

3) Use of the second card to store a different image format than the first card (for example, raw to cf, jpg to sd). This is, as far as I can tell, the worst possible setup for the camera if the user wants to do something like BIF. It seems to divide the camera buffer into 2 partitions, one for raw and one for jpg, and hence lowers the burst capacity of the camera to far fewer images than with any other setup. I found this out only by testing as there does not seem to be any documentation about it.

I really like my 5D3 and think that the ability to make backup copies of my images is very important. I have not lost many images due to camera failure (I lost 2 images with my first 5D3 due to some failure), but prefer to be safe than to be sorry.

Noogy
Noogy Senior Member • Posts: 1,483
Re: CF or SDHC

tremorhand wrote:

Just got the 5D3. Why two different memory card types? Is one better than the other?

SDHC saves more space, occupies a smaller footprint hence seems ideal for "back up." I thought it was a big deal, having shot on the 7D for more than three years now, when I bought the 6D a few months back. As it turned out, SDHC has become a lot more convenient to use in view of the fact that all of my laptops have a built-in SDHC card reader. Other than that, the differences seem to be irrelevant.

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Ultradan Contributing Member • Posts: 597
Re: CF or SDHC

One thing that might have slipped all of the mega-pixel-peepers minds here is that there is a very good use for two slots: shoot in RAW + L or even RAW + M that way you can always have a copy of the RAW image but for ease/speed of workflow you can cycle quickly through the lower res Jpegs deciding which shots you want to work on instead of importing huge amounts of un-useable photo's (especially when shooting moving sports sequences)

I mention this as I have an older 2008 15" Macbook pro and though it is fine with the RAW files from my 1DMK2 it struggles to display the RAW filea from my 550D when I want to browse quickly through the folder using the eye button in finder.

nekrosoft13 Regular Member • Posts: 441
Re: CF or SDHC

tremorhand wrote:

Just got the 5D3. Why two different memory card types? Is one better than the other?

cf faster, better, more durable, harder to loose.

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Noogy
Noogy Senior Member • Posts: 1,483
Re: CF or SDHC

Ultradan wrote:

One thing that might have slipped all of the mega-pixel-peepers minds here is that there is a very good use for two slots: shoot in RAW + L or even RAW + M that way you can always have a copy of the RAW image but for ease/speed of workflow you can cycle quickly through the lower res Jpegs deciding which shots you want to work on instead of importing huge amounts of un-useable photo's (especially when shooting moving sports sequences)

I mention this as I have an older 2008 15" Macbook pro and though it is fine with the RAW files from my 1DMK2 it struggles to display the RAW filea from my 550D when I want to browse quickly through the folder using the eye button in finder.

But I can do the same with my 64gb SDHC. I can simply select the default view in my laptop, whether to prioritize viewing jpegs or RAW, or configure my software the same way, so I can be afforded a quick jpeg view of which shots are worth keeping/discarding. You don't need to have two slots to do what you just described. On the 6D I can even transfer all the files over wifi as soon as I am done shooting, making two card slots perfectly optional.

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