It can be difficult to know which SD card is the best for you and your camera. Maybe you’re most concerned about shooting 4k video, using a GoPro, or you just want to shoot as many RAW files as possible in one go. Even within the Sandisk brand, there are multiple types of memory card, like the Sandisk Extreme Plus, Extreme Pro, Extreme and Ultra and Ultra Plus.
You might think it doesn’t matter which you pick, and maybe you should just go for the cheapest. I used to do this and so have built up a collection of all of these cards, and let me tell you, there are performance differences that do matter in the real world.
The Best SD Card: Sandisk Extreme vs Extreme Pro vs Extreme Plus vs Extreme vs Ultra vs Ultra Plus
Let’s take a look at the specifications of these sd cards, then see the real world testing results, and see what differences there are between the memory cards in practice.
Sandisk Extreme Plus vs Pro vs Extreme vs Ultra vs Ultra Plus Specifications
Note: The Sandisk Extreme Plus and Ultra Plus are no longer widely available, so will not be included in this list.
|Capacity:||Up to 1TB||Up to 256GB||Up to 256GB|
|Video Class:||Suitable for 4k||Suitable for 4k||Suitable for 1080p|
|Sequential Write Speed:||90MB/s||60MB/s||20MB/s|
|Sequential Read Speed:||Up to 170MB/s (90MB/s in real world testing)||Up to 150MB/s (90MB/s in real world testing)||Up to 100MB/s (90MB/s in real world testing)|
Which SD Card Specifications Don’t Matter?
Card Type: All of the cards shown are SDXC. This only refers to the internal data architecture of the card, and is dependent on capacity. Smaller capacity cards from the same model would be SDHC. This is not something you need to worry about.
Bus Type: This refers to the theoretical maximum read and write speeds for the card. Although UHS-II cards are now available, they are prohibitively expensive (5x the price of the UHS-I cards), and they require cameras that support the extra number of pins in these cards, otherwise they operate at UHS-I speeds. Currently, there is a very limited list of cameras that support UHS-II, so we are only looking at UHS-I cards in this list.
Speed Class: This refers to the theoretical maximum read and write speeds. You are much better off to look at the actual read and write speeds for each card.
Durability, Operating Temperature & Storage Temperature: All flash memory cards has similar physical characteristics, and so these items will be identical or near identical for every memory card you buy. The only possible difference is that some memory cards do have metal casings rather than plastic to add crush protection (ie. stepping on it!). None of the cards we are looking at have this, and I have never found it to be a useful feature.
Which SD Card Specifications Do Matter?
Capacity: This is the number of photos and video files you can store on the memory card. It is always worth buying the highest capacity you can afford. Bear in mind though, that having fewer, higher capacity cards puts your photos more at risk of being lost if there was a catastrophic failure of one card.
Sequential Write Speed:
The key piece of information to distinguish memory cards is the Sequential Write Speed.
Every digital camera comes with an internal memory buffer. When you press the shutter, the photo is initially stored in this buffer, from where it is then transferred to the memory card. This internal memory has much faster read and write speeds than any memory card, and is used to store a burst of photos taken in quick succession. If your camera shoots at 3 frames per second (fps), 10 fps or 20 fps, this is because of the size of the internal buffer.
As soon as photos are stored to the internal buffer, they begin to be transferred to your memory card for long term storage, and they are deleted from the buffer once they are on the SD card.
Photos cannot be written to the memory card as fast as they can to the buffer, and once the buffer is full, you cannot take any more photos, until space has been freed up on the buffer.
Therefore, the write speeds of the memory card determine how many photos you can take in a burst before the buffer fills up and you must stop shooting.
The sequential write speed for each memory card refers to the speed at which writing can be maintained over longer time lengths. This is a figure from testing in an R&D lab, and it is not clear from my research exactly what length of time the sequential write speed is measured over, but this is likely to be a few minutes.
If you want to see real world examples of what these write speeds mean in practice, take a look at the next section below.
Sequential Read Speed:
Read speed is less relevant than write speed for your memory card. This is simply the speed at which data can be transferred from it to another device, like your computer. A few years ago, the limiting factor in getting photos onto your computer quickly was your card reader and USB connection. Nowadays, it’s more likely to be your memory card.
Bear in mind that quoted Maximum Read Speeds are likely to be about double the real world performace you will see.
In practice, all the memory cards have very similar quoted read speeds, from the Sandisk Ultra of (up to) 100MB/sec to the Sandisk Extreme Pro of (up to) 170MB/sec. This means that even with a full memory card, you are likely to only see a few tens of seconds difference in transfer speeds to your computer, particulary as the real world read speeds will all be below 100Mb/s.
Unless you are a professional sports photographer or photojournalist, where seconds count, you can ignore Sequential Read Speed.
Real World Tests of the Sandisk Extreme, Extreme Pro and Ultra
To show the practical differences between each memory card, I tried a number of tests with my Canon 6D, as below:
|Max Number of Photos Before Buffer is Full||26||22||18|
|Time to Write a Burst of Ten Photos to Memory Card||5 sec||6 sec||7 sec|
|Time to Transfer 20GB of Photos to Computer||4 min||4 min 10 sec||4 min 30 sec|
There are clear differences between the three cards we have tested today, although for most non-professional uses, you are unlikely to see any difference between the Sandisk Extreme and Extreme Pro. Choosing either of these would be the sensible choice. If you have a choice between a lower capacity Sandisk Extreme Pro, or a higher capacity Sandisk Extreme at the same price point, I would always recommend buying the higher capacity card.
It’s clear from the specifications and from my testing, that the Sandisk Ultra is significantly below par when compared to the other two models. Although it is the cheapest of the three, it will struggle to cope with recording 4k video and any length of burst shooting. Choosing this model would be a mistake.
You should also always bear in mind that the performance of any memory card is dependant on the camera it is in. It’s worth looking in your camera’s user manual, particularly if it is an older model, as there may be hardware limits on the maximum read and write speeds, and capacity.