Nikon D5200 vs D7100: 1. Sensor – Aliasing vs non-aliased
Both cameras have a 24-megapixel APS-C sensor measuring 23.5 x 15.6mm. Nikon claims that the sensor in the Nikon D7100 is a brand new design, but the key point for most users will be the fact that Nikon’s left out the OLPF (Optical Low Pass Filter), also known as the anti-aliasing filter, in front of the sensor.
These are used to prevent moiré (interference effects) with fine patterns and textures, but at the cost of slightly blurring the fine detail. Nikon’s decided that the size and resolution of this sensor makes moiré unlikely and that the gain in sharpness from removing the filter is a bigger benefit.
As a result, although the D7100 and D5200 have the same resolution, you can expect the fine detail from the Nikon D7100 to be slightly sharper.