Burst Buffer Depth: Beyond Frames per Second

What Is Burst Buffer Depth?

When you press the shutter and hold it down, the camera continuously captures frames. Each image is first written to a temporary internal memory, called the buffer, before it is transferred to the memory card. The buffer acts as a waiting area that allows the camera to keep shooting while the card slowly writes data.

The depth of that buffer is how many images it can hold at once. Once the buffer is full, the camera must pause or slow down to give the card time to catch up. At that point, the shooting rate drops from the advertised burst rate to a much slower speed, often called the 'sustained' or 'continuous low' rate.

Buffer Depth vs. Burst Rate

Burst rate, usually expressed in frames per second (fps), indicates how fast the camera can capture frames during a single burst. Buffer depth tells you for how long that speed can be maintained. A camera can advertise a high burst rate but have a shallow buffer, meaning it only sustains that speed for a second or two before slowing down. On the other hand, a modest burst rate with a deep buffer can allow longer stretches of continuous shooting, which is often more useful for unpredictable action. See our burst rate and frame rate guide for more on the differences.

Think of burst rate as the speed of water flowing from a tap and buffer depth as the size of the bucket underneath. A fast stream fills a small bucket quickly; a slower stream might fill a larger bucket more slowly, but it gives you more total water over time. For photography, the bucket is your buffer.

What Determines Buffer Depth?

Several factors go into a camera's buffer depth. The obvious one is the amount of built-in RAM. More memory means more images can be stored before the buffer is full. The processing power of the camera's image processor also plays a role, because it compresses and processes images before they enter the buffer, which can reduce the file size and effectively expand the buffer.

The file format you shoot matters as well. A RAW file is larger than a JPEG, so a buffer holds fewer RAW images than JPEGs at the same resolution. Cameras that offer compressed RAW formats, which discard some non-essential data while preserving most of the original information, can fit more images in the same buffer. The write speed of the memory card also influences how quickly the buffer empties. A fast card, such as one that uses a newer standard like CFexpress or high-speed UHS-II SD cards, can keep up with the camera's output better and allow longer bursts. For a deeper dive on file formats, read our RAW format guide.

Camera manufacturers and industry bodies like CIPA publish specifications and educational resources that explain these factors, which helps you compare models based on what you need.

Why Buffer Depth Matters in Real Shooting

For action photography, the buffer is often the deciding factor between capturing the perfect moment and missing it. Sports, wildlife, and even busy street scenes are unpredictable. A shallow buffer forces you to release the shutter and wait, which can cause you to miss the decisive instant. If you're looking for a camera for action, check our picks for best full-frame mirrorless cameras or best action cameras.

Even for casual users, a full buffer can be frustrating. If you try to shoot a burst of your child's birthday cake blowing moment and the camera slows after three frames, you might lose the reaction shot. Understanding buffer depth helps you choose a camera that matches how you shoot.

How to Choose a Camera Based on Buffer Depth

When comparing cameras, look at the continuous shooting specification. Many manufacturers list both a maximum burst rate and a buffer capacity, often expressed as the number of frames you can shoot at the maximum rate before the camera slows. If these numbers are not prominent, they are usually buried in the spec sheet or user manual. Pay attention to both RAW and JPEG buffer figures, because they differ significantly. Our best APS-C cameras guide includes detailed specs for many models.

Consider your typical subjects. If you photograph sports, birds in flight, or any fast-moving event, a deep buffer is a priority. For general photography, a modest buffer is often fine, as you rarely need to fire off long sequences. Also consider the memory card slot. A camera that supports faster cards will be able to empty its buffer more quickly, effectively giving you longer burst lengths even with a smaller physical buffer. Our memory card guide explains card speed classes and compatibility.

Tips for Getting the Most from Your Buffer

You can stretch your effective buffer without buying a new camera. Switch from uncompressed RAW to a compressed RAW format if your camera offers it. The file size drops, the buffer holds more images, and the visual difference is often negligible. Similarly, shooting JPEG instead of RAW roughly triples the number of images the buffer can hold, though you sacrifice editing flexibility. Read our RAW vs JPEG workflow guide to weigh the trade-offs.

Use a memory card with a high write speed. Even with a deep buffer, a slow card makes the camera wait longer after the buffer fills. Read our memory card guide to understand the speed classes and pick a card that matches your camera's capabilities. Finally, try shorter bursts and spread them out, so the buffer has time to empty between shots.

What to pick for your use

Questions

What is burst buffer depth?

It is the number of frames a camera can store in its internal memory during a continuous burst before it has to slow down to give the memory card time to catch up. See our burst rate guide for related concepts.

Why does my camera slow down after a few shots?

Your camera's buffer is full. The camera must wait for the card to write enough images to free up space, which reduces the shooting speed. Using a faster card can help, as explained in our memory card guide.

Does a faster memory card increase buffer depth?

No, buffer depth is a physical property of the camera. However, a faster card empties the buffer more quickly, which means you can start a new long burst sooner and may effectively get longer sustained shooting from a full buffer.

What's the difference between burst rate and buffer depth?

Burst rate is the maximum frames per second during a short burst. Buffer depth is how many frames those bursts can include before the rate drops. Both determine your continuous shooting capability. Learn more in our burst rate guide.

Can I increase my camera's buffer?

Not directly. But you can shoot in JPEG or compressed RAW to make the buffer hold more images, and use a fast card to clear it faster. Check our RAW format guide for format options.

Is buffer depth important for video?

For video, the camera typically writes directly to the card rather than using a burst buffer, so continuous recording time is limited by other factors like file format and card speed, not burst buffer depth.