Does 120hz or 240hz Really Make A Difference?

Carla Rowland wants to know how important the refresh rate is when shopping for an HDTV

A 120 or 240hz refresh rate can certainly improve the look of an LCD HDTV, especially when dealing with fast-moving content like sports or action movies. But the difference may not be all that significant.

It's worth remembering that there's no such thing as 120hz or 240hz content--just 24hz and 60hz, because film is shot at 24 frames per second (fps) and video at 60. One key advantage of that faster refresh rate is that it can show both types of content at their native speed, since both 24 and 60 divide evenly into 120 and 240. This results in better-looking film-originated content, although the difference is only occasionally noticeable.

Every 120- and 240hz LCD TV I've seen can interpolate virtual frames between the real ones. In PC World tests, we've noted that this interpolation can help in limited situations--most obviously with text scrolling horizontally across the screen. We've also noted a few cases, in some sets, where it could cause problems with other moving images, although this can always be fixed by adjusting the interpolation setting. Just don't look for a setting called interpolation, HDTV manufacturers call it things like Motionflow, Smooth Motion Technology, and Auto Motion Plus.

November 16: I'm adding links to two other articles on this subject, neither of which agree entirely with my opinion. PC World Senior Editor Melissa J. Perenson found the differences between 60 and 120hz more significant than I did. But Dr. Raymond M. Soneira, President of DisplayMate Technologies, argues in an extensive article that higher rates offer no significant, real-world advantage. That the three of us looked at very similar data (in the case of Melissa and myself, identical data) and came to different conclusions shows that when it comes to image quality, there's no completely objective view. My thanks to reader Chris Cook for bringing Dr. Soneira's article to my attention.

Add your comments to this article below. If you have other tech questions, email them to me at answer@pcworld.com, or post them to a community of helpful folks on the PCW Answer Line forum.

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