Rudy Winston
Rudy Winston

Rudy Winston has over 14 years experience with Canon USA's Pro Products team, and has been responsible during that time for training Canon's staff on new products, creating presentations for customers and dealers, numerous writing projects, and providing technical assistance to professional and amateur photographers.

EOS-1D X CF Card Management

April 19, 2013

The EOS-1D X is the first Canon EOS camera to have dual CompactFlash (CF) card slots (previous EOS-1D and EOS-1Ds models, such as the EOS-1D Mark IV, have had dual slots but one was dedicated to SD cards only). With two CF card slots, the new EOS-1D X frees the user from concerns about needing to have two types of cards and accommodating card readers and, instead, offers some interesting methods of combining the two available card slots. This article will give some insight into how to manage Dual Card Slots with this new top-of-the-line EOS camera.

CF card compatibility

The EOS-1D X is compatible with both Type I and the thicker Type II CF cards in either of its two CF card slots. It will work with cards that are compliant with the UDMA 7 standard (theoretical speeds up to 167MB/sec.), as well as previous UDMA-compliant cards. In fact, for best performance (especially for shooters who expect to shoot high-speed sequences of RAW image files and/or record HD video), we strongly suggest UDMA-type CF cards from any major CF card manufacturer.

For technical reasons, previous Microdrive CF cards are not compatible with the EOS-1D X and cannot be used. If a Microdrive is inserted into the camera, a warning will appear on the LCD monitor reminding the shooter that the card is incompatible.

While currently available cards (as of mid 2013) typically offer speeds up to roughly 40- 45MB/sec., as faster UDMA 6 or 7-compliant cards are becoming available, the EOS-1D X is ready to utilize them.

Using the two card slots

The EOS-1D X’s Dual Card Slots are labeled “1” and “2.” If one card is being used, either slot could be used for the card. 

But users are free to insert two CF cards into the camera, if they desire. Note that if two cards are inserted into the EOS-1D X simultaneously, they do not need to be identical in capacity or brand. The options available when two cards are installed in the EOS-1D X will be familiar to owners of previous EOS-1D or 1Ds Mark III/Mark IV models, but will be new to users who haven’t worked with these models. With two cards installed, the following series of commands in the Set Up Menu dictates how the camera will record images on the two cards:

Set-up Menu (screen 1) > Record func + card/folder sel. > Record func.

  • Standard: The camera records to one card only. The photographer dictates on the menu whether it’s the card in Slot 1 or 2. If this card fills up, shooting stops and a “Card Full” message appears on-screen. User must select the other card to continue shooting or remove the full card and install another CF card with available space.
  • Auto switch card: Camera will automatically continue recording on second card when first card fills up. User chooses Slot 1 or 2 as initial card for recording. Some users refer to this as “relay recording.”
  • Record separately: Record same images to each card at different quality settings. Unlike many competitive cameras, any RAW or JPEG quality setting is possible. It’s possible to record small resolution JPEGs to one card and large JPEGs to the other — this is not simply a RAW on one card, JPEG on the other option but that’s possible too.
  • Record to multiple: Record the same image, at the same quality settings, to both cards. This is a pure back-up function, letting the user select his or her Image Quality setting and record each image at that setting onto two cards.

For those who are using only one memory card, if any setting other than “Standard” is active within the Record Function menu, a warning message will appear saying that the camera cannot perform the dual-card task that the active menu command asks it to. You are still free to shoot with the one card and by selecting “Standard,” you will avoid the on-screen warning message.

Image copying

If a user prefers shooting with one memory card at a time, he or she may want to copy original in-camera files from the memory card they’ve been using to another source. When it’s not practical to copy to a laptop or external hard drive, the EOS-1D X’s Image Copy function may be the next best thing. It allows users to take the content from a memory card, insert a new card with available space and copy them to that second card.

Playback Menu (screen 1) > Image Copy

Users will be asked to select the original source card in Slot 1 or 2, then available space on the opposite card is displayed on-screen. From there, the user has three options:

  • Select Image: User goes through source card, highlighting image(s) he or she wants to copy. Those images will be copied to the other CF card.
  • Select Folder: User selects one or more image folders on source card to be copied. These will be copied to the other CF card.
  • All image: All image files on source card will be copied to the other CF card.

The Image Copy function is again very similar to that in recent top-of-the-line EOS models, such as the EOS-1D Mark III or EOS-1Ds Mark III. But it’s another new capability for EOS users who may have not worked with the EOS-1D series cameras.

Unlike the Mark III and Mark IV series models, the EOS-1D X is not compatible with portable external hard drives. There is no “USB Host” capability, either with the camera’s own USB port or with its new accessory wireless transmitter. However, the EOS-1D X’s exciting new Ethernet capability does mean that it can be directly connected to many computers or networks and have images copied in that fashion.


Dual Card Slots open the door to a new level of convenience and security for the photographer. And unlike previous versions of the EOS-1D, the EOS-1D X doesn’t require the user to concern him or herself with two different types of memory cards. Dual CompactFlash memory card slots and the available options for them may, at first, pale in comparison to features such as the camera’s 61-point AF system, 12 fps shooting capability or its low-light image quality. Yet it’s a capability with everyday appeal and many different types of shooters will be able to see immediate ways it could help in their daily shooting.

Commercial or event shooters who need may need both full-resolution and lower-resolution files for publishing or printing needs will love the “Record Separately” option. All the full-resolution files (RAW or JPEG) can stay with the shooter and a separate card with exclusively lower-res files can be given to the client at the end of a shoot, for example.

Shooters working events at important shoots that can’t be re-done — anything from the Super Bowl to a wedding — can get the peace of mind with an instant duplicate of their original full-resolution files using “Record to Multiple.”

Other photographers recording HD video or extensive still-image shooting may not feel the need to always record duplicate files in-camera. But the simple ability to ignore whether a card is nearly full and continue freely shooting with the “Auto Switch Card” option gives that user one less thing to worry about.

For many digital shooters, the specter of losing images from data corruption on a memory card is a nagging fear they carry every day. Knowing that the EOS-1D X can simultaneously record to two cards at the same time or provide the freedom to select and copy files during a break in a shoot, can relieve a lot of that pressure.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

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