A folder of sequential images does not determine how quickly the resulting movie should play. Frame rate supplies that timing. Decide whether you want a fast time-lapse, an animation or a slow visual record before creating the movie.

Keep the original images untouched and prepare a working sequence with clear, consistently numbered names. Check its intended first and last image and remove unrelated test images from the working selection. A movie cannot explain an accidentally omitted stage of the sequence.

Plan duration from the frames

For a sequence in which each image contributes one frame, duration in seconds is the number of frames divided by frames per second. For example, 240 frames at 24 fps produce 10 seconds; at 12 fps they produce 20 seconds. This is a timing calculation, not a promise that either result will look smooth.

In QuickTime Player on Mac, choose File, Open Image Sequence. Select the sequence folder, or select the intended images, and choose the media. Set Resolution and Frame Rate. Apple also offers H.264 for greater compatibility, HEVC for better compression and ProRes for higher quality. Available frame sizes depend on the format.

Choose Open to create the movie in a new window. Use File, Save to give the result a separate name and destination.

Check sequence and playback separately

Play the saved movie from the destination folder. Check its duration against your calculation, and inspect the beginning and end. Watch for a frame that jumps backwards in the process or an unrelated image appearing briefly; investigate the source selection before changing playback speed.

Then assess whether viewers have enough time to understand the material. If the underlying sequence is correct but too fast, create a second version with a different frame rate and compare the same passage.

Keep the selected frame count and chosen rate with the project notes. A label such as final-fast does not explain how the movie was constructed, whereas those two values make the next export repeatable.

References: Apple: QuickTime image sequences, Apple: saving in QuickTime.