If you are watching on a display that expects to be fed interlaced (most SD displays do), it’ll either try to show interlace (tube) or de-interlace (flats). Either method can expose problems with images that were very sharp from the beginning – I’ve seen this again and again when working with stills in the old days.
Consider RED as being just like stills: too sharp for PAL. So, the suggestion of a vertical blur is a good one, but 0.6 pixels should be enough for most footage.
The other option is shooting 50 fps and re-interlace it in SD.
Director of the Institute of Media Research (IMF) at Braunschweig University of Arts