CF or SDHC

Started Mar 21, 2013 | Discussions
mjack101
Regular MemberPosts: 108
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Re: CF or SDHC
In reply to MikeFromMesa, Mar 23, 2013

MikeFromMesa wrote:

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.

It may very well be that we are talking at cross purposes here but in relation to your point number 2. I did a very quick and dirty test on my 5diii shooting in burst mode for 10 seconds firstly with the image only being written to the CF card and secondly with the image being written to both cards. In the first test I got 32 RAW files saved and in the second test I got just 20.

This is why I only have the camera set to record to one card at a time as this is more important to me than maybe losing images due to the CF card having a problem.

Am I missing something here?

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MikeFromMesa
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Re: CF or SDHC
In reply to mjack101, Mar 23, 2013

mjack101 wrote:

It may very well be that we are talking at cross purposes here but in relation to your point number 2. I did a very quick and dirty test on my 5diii shooting in burst mode for 10 seconds firstly with the image only being written to the CF card and secondly with the image being written to both cards. In the first test I got 32 RAW files saved and in the second test I got just 20.

This is why I only have the camera set to record to one card at a time as this is more important to me than maybe losing images due to the CF card having a problem.

Am I missing something here?

No, I don't think you are missing anything here. Your results seem consistent with how I understand the camera to work.

My testing on my 5D3 was slightly different from yours. I first set the camera to record the same image type (raw in my case) to both cards and then used burst mode until the buffer filled up (I could tell because the shutter clicks suddenly slowed down dramatically). I then set the camera to record raw to the cf card and jpg to the sd card and repeated the test.

While I don't remember the exact figures (I did this about ayear ago shortly after I bought my 5D3) my second test was only able to capture about half of the images of the first test before the buffer filled and the shutter clicks slowed down. This seemed to indicate that if different image types are being written to the two cards the camera partitioned the buffer into spaces for both types and thus reduced the buffer size available to record only one type. Hence the smaller number of images able to be recorded before the buffer filled.

In your test you were recording one type of image to (first) the cf card and (second) both cards. Since the sd card is considerably slower than the cf card in image writes it only makes sense that, given a fixed time period, the time it took to write to the sd card would decrease the numer of images written. As I said, this seems consistent with how I understand the camera to work.

My primary concern is to not lose images so I use both cards and write raw to both at the same time. I can live with the added write time. Your needs are different and you have your camera set up accordingly. That is one of the things that makes the 5D3 a great camera. It is flexible enough to allow people with different needs to use it as best benefits them.

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mjack101
Regular MemberPosts: 108
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Re: CF or SDHC
In reply to MikeFromMesa, Mar 23, 2013

MikeFromMesa wrote:

mjack101 wrote:

It may very well be that we are talking at cross purposes here but in relation to your point number 2. I did a very quick and dirty test on my 5diii shooting in burst mode for 10 seconds firstly with the image only being written to the CF card and secondly with the image being written to both cards. In the first test I got 32 RAW files saved and in the second test I got just 20.

This is why I only have the camera set to record to one card at a time as this is more important to me than maybe losing images due to the CF card having a problem.

Am I missing something here?

No, I don't think you are missing anything here. Your results seem consistent with how I understand the camera to work.

My testing on my 5D3 was slightly different from yours. I first set the camera to record the same image type (raw in my case) to both cards and then used burst mode until the buffer filled up (I could tell because the shutter clicks suddenly slowed down dramatically). I then set the camera to record raw to the cf card and jpg to the sd card and repeated the test.

While I don't remember the exact figures (I did this about ayear ago shortly after I bought my 5D3) my second test was only able to capture about half of the images of the first test before the buffer filled and the shutter clicks slowed down. This seemed to indicate that if different image types are being written to the two cards the camera partitioned the buffer into spaces for both types and thus reduced the buffer size available to record only one type. Hence the smaller number of images able to be recorded before the buffer filled.

In your test you were recording one type of image to (first) the cf card and (second) both cards. Since the sd card is considerably slower than the cf card in image writes it only makes sense that, given a fixed time period, the time it took to write to the sd card would decrease the numer of images written. As I said, this seems consistent with how I understand the camera to work.

My primary concern is to not lose images so I use both cards and write raw to both at the same time. I can live with the added write time. Your needs are different and you have your camera set up accordingly. That is one of the things that makes the 5D3 a great camera. It is flexible enough to allow people with different needs to use it as best benefits them.

Many thanks for your reply, it's a relief that I haven't been missing a trick all of this time. You are absolutely correct that the 5diii is a great camera and is capable of accommodating so many differing shooting styles.

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