Memory cards, whether they are Compact Flash, SD, or microSD, are solid-state memories used in a wide array of electronic devices, from smartphones to digital cameras, from audio recorders to video camcorders.
Memory cards are no different than the USB stick you use to share your data on the fly and the solid-state hard drive in your laptop or desktop computer. So they need the same care, as they suffer the same catastrophic failures.
Here is what you need to know about using an SD memory card for photography, but the same can be applied to Compact Flash and microSD cards.
What Format Do SD Cards Use?
SD cards are like the solid-state hard drives in your computer and as such, they use a File System to organize, read and write data.
There are several file systems available for computers, depending on the OS (Operating System) that is installed.
Windows computers use the NTFS file system, Mac computers use the APFS file system, and Linux machines use the EXT3/EXT4 file systems.
Those file systems are all different and it may not be possible to read data from NTFS drives with a Mac without buying third-party software.
While, in principle, you can format an SD card to use any file system you like, it is not a wise choice to use a file system that can only be read by one operative system if you want the widest compatibility.
A file system every type of computer can natively read is the FAT32 file system and the newer exFAT. This is why every “swappable” memory, like SD cards and thumb drives, are pre-formatted by the manufacturer in one of these two formats.
This is quite an old file system and in today’s world suffers from important limitations:
- The max size for a single file is 4GB
- Although the File System could support drives and partitions up to 8 Terabytes (TB), if you use windows to format your drive/create a partition, you are limited to 32GB – for no real apparent reason.
For these reasons, SD cards larger than 32GB are not (and should not be) formatted using the FAT32 file system.
The ExFAT is a newer version of the FAT32 file system that surpasses the limits of the old format.
Here you can find a comparison between the two file systems.
Nowadays, all memory cards larger than 32GB are formatted to use the exFAT file system.
You should check on your camera manual what is the type and maximum size of the memory cards it can handle. Old cameras may still use the FAT32 file system; thus, they can’t take full advantage of the increased size of today’s cards.
Do You Need To Format A New SD Card?
When you buy a new card, it is ready to use.
In theory, you do not need to format it, but it is good practice to format your new SD card with your camera before you start shooting.
This is because your camera may need to create a database and a particular structure in the file system.
Here is the structure my Olympus OM-D creates on a formatted SD card to organize the data.
While Olympus does this silently under the hood, some other cameras will let you know they need to create a particular structure.
If I format my card on my computer, as soon as my Sony RX10 tries to access the card, it realizes there is no database file and asks me to create it.
After hitting OK, the following structure is created on the card.
If I CANCEL creating the database, the camera refuses to use the card and asks me to insert another one.
This is a great way to let you know you have possibly inserted in the camera a card that you don’t normally use with it.
But don’t worry, whether your camera tells you or not, whatever it needs to create will be created without deleting anything that is already in the SD card.
How To Format A SD Card On A DSLR Camera
Let your camera format your card is the best way to go.
The option is somewhere in one of the camera menus: sometimes you have a “Card” menu, sometimes the option is in the more generic Settings menu.
Best is to refer to your camera manual.
Here is why formatting your card with your camera is best.
My Sony RX10 is quite old, being the first version, but it is compatible with SDHC cards, those larger than 32GB.
If I insert an SD card (up to 32GB), the camera formats it in FAT32, while SDHC (and newer) cards are automatically formatted to use the exFAT file system.
This is very good news, as we are photographers, not sysadmins in an IT company: format your card “in-camera” when you need to, and you will not go wrong.
Some cameras, like my Olympus, let you delete the images without formatting the card.
The difference between erasing and formatting is that if you choose to erase all images, the camera will clean up what is present in its own database/directories, leaving the other data on the card untouched.
Formatting the card, instead, is a far more destructive process that will cause all data on the card to get lost.
Before You Format Your Memory Card
Before you format your card, either in-camera or on your computer, make sure you have downloaded all the images and videos you wanted to keep.
It is always a good practice to have a spare card with you: should you realize you don’t have enough space left on your card and you didn’t download the images it contains (or you are not sure you did), better to swap cards rather than formatting.
Once you have formatted your card, there is no simple option to recover your data (more on that later).
Does Formatting A SD Card Delete Everything? Quick Vs Full Format
There are two types of formats: a full format, where all the data is physically deleted by the memory, and a quick format, where the file system table is erased so that the whole memory is accessible and you can write over the older data.
If you have sensitive data or images and you want to make sure you got rid of them, always do at least a full format of the memory. Some software will even let you write dummy data all over the memory to ensure what was on the card or hard drive cannot be recovered.
Because a full format is time-consuming, particularly with high capacity cards, cameras will perform a quick format rather than a full one.
If you formatted your card by mistake, turn your camera off and replace the “offended” card with a different one. This ensures you will not overwrite your older data, increasing the chance to recover them with dedicated software.
Backup Any Images You Want To Save
Whether you want to format your card because you are running out of space or edit your images, you need to download your photos and movies from the cards into a computer.
There are different ways to do that; let’s see a few of them.
Backup your images on your computer
This is the classic way to download your images off the card to use a computer. This can be done in different ways:
- Some computers have an SD reader: pop in your card and move your images wherever you want
- You may not have an SD reader in your computer, but you have USB ports: get a USB/SD card reader. Many adapters allow you to insert both SD and microSD cards directly.
- Connect your camera to your computer using the cable, then turn it on. You will be asked in what mode you want to connect the camera: choose Storage. You will now see the SD card in your computer as an external device you can access and use.
Of the three options above, connecting the camera via cable is the less interesting option: first, every camera has its own type of cable, so you need to find it/bring it. Next, you will be using your camera batteries, and transfer speed can be quite slow.
Save the cable connection for when you need to shoot tethered and control your camera from the computer.
For this reason, a card reader is a must-have.
Backup Your Images On The Go
When you are on the go, you may not have a computer with you and need to rely on your smartphone or tablet.
A wireless card reader like the RAVPOWER FileHub Voyage is the optimum companion for your photographic travels.
This device is affordable and it creates its own wireless network so that you can access wirelessly to the external thumb drives, hard drives, and/or SD cards connected to it directly from your phone or tablet.
And the internal battery can be used to recharge your phone, tablets, and compact camera.
The newer models allow you to do a backup of your SD card at the push of a button, eliminating the need to use a table to transfer the data.
I just got one to replace my first version of the RAVPOWER FileHub.
How To Format A SD Card On A Mac
If you need to format your card on a Mac, you need to use Disk Utility.
Connect the card, wait for it to show up in the finder, and open Disk Utility. Select the card and click on Erase. Choose the Name and the proper file system (exFAT or FAT32) let the program do the rest.
How To Format A SD Card On Windows 10
Windows computers have similar options and you can format your card in many ways. The classic way consists of opening This PC… and right-click on the icon of the SD card to format.
From the contextual menu, choose Format and you will be prompted with different options for formatting the card, including whether you want to perform a Quick Format (default option) or a full one.
Remember to choose the right type for the File System
Why Can’t I Format Or Write On My SD?
Sometimes, your camera may tell you it cannot save on the card, or you cannot format it.
Have you even noted the little switch on the side of your SD card? Flick it downwards, and you will forbid writing on the card: the card is now write-protected.
Mind that microSD cards don’t have a write protection switch, but SD adapters that “turn” a microSD into an SD-sized card do have the switch.
If this is the case, your camera will let you know the card is protected so as soon as you turn it on.
The switch is usually rather stiff, but if it gets loose, it can move while inserting the card, so make sure your card is not protected.
If the switch is not the cause, something else is wrong with the card: try checking if the golden contacts are clean. You can clean them with a soft pencil eraser.
If this too does not fix the problem, you should replace the card: they are not serviceable.
How Do I Fix A Corrupted SD Card
If you cannot read the card, there is not much you could do. I would try to recover the data and then toss the card away and replace it with a new one.
This is also an option if you have formatted your card by mistake: providing you didn’t use it after the fact and that you did a quick format, there are good chances you will be able to recover most of your images and videos.
SD cards are very common and very easy to use. There is not much you could do wrong with them, aside from deleting data by mistake. You can toss them in the water, forget them in those jeans that are now in the washing machine and chances are that once dry, you will be able to use your cards normally.
But behind the scenes, there is quite a lot going on and you should know the good practices to avoid catastrophic loss of data.
And just because they are cheap and come with large storage space, you should still avoid using them for long-term storage or as a cheap replacement for solid-state hard drives, as they are often not optimized for this type of job, with limited read/write life cycles.