The Canon EOS 40D has one card slot and can use CompactFlash memory cards that are up to 128GB in storage capacity. Type I or II CF memory cards can be used and the camera is UDMA compatible.
The main spec to look at when comparing CF cards for the Canon 40D is the read speed. For example, the fastest CF memory cards available will save minutes over slower cards when transferring a large number of images.
If you don't want to read explanations of specifications, my Recommended CF card is:
- Fastest card available and largest supported capacity.
- Read speeds up to 160MB/s.
- Write speeds up to 150MB/s.
- Water, x-ray, & shock proof.
Once you have a working memory card, expand your creativity with another lens. Check out the 7 Best Canon 40D lenses.
Best CF Cards
The best value card is going to be either 16GB or 32GB. Larger or smaller cards are going to be more expensive per GB.
A professional card isn't going to add a noteworthy amount to the price. Having a high-speed card will remove the need to buy another card with a future camera upgrade.
Recommended CF Cards
- Transfer speeds up to 160MB/s.
- Video Performance Guarantee sepc VPG 65.
- Limited lifetime warranty.
- Read speeds up to 120MB/s.
- Write speeds up to 85MB/s.
- Sustained data recording of 20MB/s.
- Water, x-ray, & shockproof.
- Speeds up to 50MB/s.
- Excellent reliability and value.
- Ideal for mid-range DSLRs.
Memory Card Reader
The UGreen 4-in-1 memory card reader can use four memory card formats. These cover everything camera manufacturers make use of in all but their newest professional-level cameras.
The UGREEN memory card reader connects over USB 3.0. The USB 3.0 transfer speeds will be faster transfer rates than what the Canon 40D can reach using the USB transfer mode.
There are plenty of favorable customer reviews for the card reader, which I agree with. I would recommend it because it has been compatible all the computers (Windows, Mac, and Linux) I have plugged it into.
The cable stops card slots from being blocked by other devices or accessories that are being used in an neighboring port.
When I searched for a card reader that would be used while traveling, I needed to send a couple of orders back. I came across the most commonly seen problem mentioned in customer reviews, the memory card readers did not work with my computer.
The ugreen reader can use the following card types:
- CompactFlash Cards
- SD, SDHC, & SDXC Cards (UHS-I supported)
- Memory Stick (MS), MS Pro, MS PRO-HG, & MS XC DUO
- MicroSD, Micro SDHC, & Micro SDXC Cards
Compact Flash Card Types
Two separate types of CF cards exist. A card can be either Type I or Type II.
The only difference between the types is the thickness of the cards. All other dimensions of the cards are the same.
- Type I - 3.3mm thick
- Type II - 5mm thick
The Type II spec made it possible to use Microdrives with the Canon 40D. A Microdrive was just a compact mechanical harddrive.
Compact Flash cards had small storage capacities when they were first released. Microdrives allowed for larger amounts of storage.
Microdrives are no longer produced. Due to their mechanical nature, the drives had a high failure rate.
Another use of the Type II slot is for CF card adapters. An adapter makes it possible to use an SD or MicroSD card in a CF slot.
Avoiding Card Read Errors
One of the most common problems with cameras that use Compact Flash cards are bent card reader pins. When a pin is bent, you may see any of the following errors:
- Err 02
- Err CF
- No CF
To avoid bent pins, never force a Cf Card into the Canon EOS 40D. The additional space for a Type II card can allow for a Compact Flash card to end up being misaligned.
If the card does not easily slide into the card reader, remove it and check the alignment of the card. Also, check the card for any damage.
If everything looks fine, carefully line up the CF card and try inserting it again.
The best Canon EOS 40D memory card can also be used in the following cameras: