The dynamic contrast ratio for the LN52A750 is 50,000:1. The R1F at the end of the other model is the full model number, so both units are essentially the same model number.
Hope that helps!
Electrozone says the LN52A750 has a contrast ratio of 50,000:1 and the LN52A750R1F has a contrast ratio of 100,000:1. Is this true? I can not find anywhere that shows a Samsung LN52A750R1F having a 100,000:1 contrast ratio, including the Samsung website. Does anyone have information on this subject?