A slower card does not reduce image or video quality by itself. The files are digital, so a reputable camera won’t make them “worse” just because the card writes more slowly.

What card speed does affect is performance:

• how long you can sustain continuous burst shooting before the camera buffer fills
• how quickly the camera recovers after a burst
• how responsive in-camera review/browsing may feel

If the card is too slow for your shooting rate and file size, the camera will usually just slow down or “stutter” once the internal buffer fills. The shots it does record should still be fine.

So if your Class 2 card gives you acceptable burst speed and your video mode records reliably, there’s no quality penalty in using it. A faster card is mainly worthwhile if you want longer sustained bursts, quicker clearing of the buffer, and snappier camera operation.

In short: faster cards are not a myth, but they’re mostly about speed and workflow, not image quality.