What a memory card actually limits
A camera writes images into a fast internal buffer, then empties that buffer onto the card. Shoot a long burst and the buffer fills; the camera slows or stops until the card catches up. That catch-up time depends on the card's sustained write speed, the bus the slot supports, and the file type you record. A faster card does not make the camera shoot more frames per second, but it shortens the wait afterwards.
For video the rule is simpler. The card must write continuously at least as fast as the camera's bitrate, with headroom. If it cannot, recording stops. That is why the minimum sustained write ratings matter more than the large read-speed number printed on the front of the card.
Before comparing cards, open the memory card section of your camera manual. Most makers list recommended card types for each video mode, and that list is a more reliable guide than any marketing label.
Reading the label
The SD Association defines most markings on SD cards. Here is what each tells you.
Bus: UHS-I or UHS-II
UHS-II cards have a second row of pins. They work in UHS-I slots but fall back to UHS-I speed.
Speed class: U3, V30, V60, V90
Minimum sustained write: U3 and V30 mean 30 MB/s, V60 means 60 MB/s and V90 means 90 MB/s.
CFexpress Type A and Type B
Different physical sizes, not interchangeable. Some bodies with CFexpress Type B slots also accept XQD; check your manual. The VPG rating indicates sustained video write.
Editorial comparison: card choices by use
Recommendations are qualitative editorial judgements; your camera's manual overrides them.
| Shooting style | Suggested rating | Bus | Capacity approach | Notes |
|---|---|---|---|---|
| Landscape, travel stills | U3 / V30 | UHS-I is fine | Several mid-size cards | Spreads the risk of loss across cards |
| Sports and wildlife bursts | V60 or V90 | UHS-II or CFexpress | Large, fast cards | Buffer clearance is the gain |
| 4K video, standard bitrates | V30 to V60 | Match slot | Large | Check per-mode list in the manual |
| High bitrate or intra-frame video | V90 or CFexpress | UHS-II or CFexpress | Very large | Some modes require CFexpress |
| Weddings, paid events | V60 or above | Match slot | Two cards, backup mode | Dual-slot backup protects the client |
Card handling checklist
- Format new cards in the camera, not on a computer
- Use a reader that matches the bus: a UHS-I reader slows a UHS-II card
- Carry cards in a hard case, labelled used and empty
- Buy from authorised sellers; counterfeit cards are common
- Test new cards with a full burst and a long video clip before a trip
- Back up the same evening; cards are not archives
Triggering without touching the camera
Pressing the shutter button nudges the camera, which shows up as softness in exposures from roughly a tenth of a second to several seconds. The camera's two-second self-timer fixes this for free in static scenes. A remote becomes worthwhile when timing matters, when you need Bulb exposures longer than thirty seconds, or when you cannot stand beside the camera.
Wired remotes plug into a port specific to each system; Canon's RS-60E3 and Nikon's MC-DC2 are two examples tied to particular port types. They need no pairing and use little or no battery. Intervalometers add timed sequences for time-lapse and star trails, although many current bodies include an interval timer in the menu. Radio remotes work through walls and at distance. Infrared remotes need line of sight. Smartphone apps offer live view and settings control but can drain the camera battery and take time to connect.
| Remote type | Reliability | Range | Battery impact | Best for |
|---|---|---|---|---|
| Wired cable release | High | Cable length | Very low | Long exposures, Bulb |
| Wired intervalometer | High | Cable length | Low | Time-lapse, star trails |
| Radio remote | High | Long | Low | Wildlife camera traps, group shots |
| Infrared remote | Medium | Short, line of sight | Very low | Self-portraits, indoors |
| Smartphone app | Medium | Medium | High on camera | Remote framing, hides |
Selection tree: what keeps your frames moving?
Does the camera stall after a burst?
Move to a faster sustained-write card on the fastest bus your slot supports. Shooting compressed raw also helps.
Does video recording stop unexpectedly?
Your card's sustained write is below the bitrate. Check the manual's card list for that mode.
Are long exposures soft?
Exposures under 30 seconds
Use the two-second self-timer first. If timing matters, add a wired remote.
Exposures over 30 seconds
A wired remote with a lock, or an intervalometer, on a stable tripod.
Do you need to trigger from a distance?
Radio remote for reliability; app control if you also need to see the frame.