The “V” marking on an SD card is its Video Speed Class. The SD Association defines these classes by minimum sustained sequential write speed: V30 means at least 30 MB/s, V60 at least 60 MB/s, and V90 at least 90 MB/s. See its current Video Speed Class standards and speed-class explanation.

That number is useful, but it does not by itself guarantee that a card works in every camera or recording mode. The camera’s manual and the exact mode you want to use decide what is required.

What the V marking means

A sustained write-speed class is relevant because a camera has to keep writing a stream of video data to the card. If the card cannot keep up with the camera’s needs, recording may stop or the mode may be unavailable. A higher number indicates a higher minimum class, but other card and device specifications still matter.

Do not confuse a card’s advertised peak read speed with the minimum sustained write class. Read speed often describes how quickly files can be copied off the card; recording depends on writing data to it.

Match the card to the camera

Check the manual or manufacturer support page for the minimum card class for your resolution, frame rate, bit depth and codec. Requirements can differ between modes on the same camera. Also confirm the card type and capacity are supported.

For example, a V30 card may meet the requirement for one recording mode but not another. Avoid assuming “4K” always needs one specific class; manufacturers define their own supported settings and may specify additional conditions.

Test your recording setup

Format the card in the camera when the manual recommends it, then run a test at your intended settings. Record longer than a few seconds, review the clip, and confirm the camera reports no write-speed warning. Keep a spare compatible card for important shoots.

Use current manufacturer documentation before purchasing. Card labels help narrow the choice, but compatibility should be checked against the exact camera and recording mode you plan to use.

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