Image Sensor & Processor:
Both features almost same size sensor, megapixel, and expeed 3 image processor, so no difference here.
Optical low pass filter (OLPF) is no longer used in D7100, on the other hand Nikon D5200 uses Optical low pass filter, so with D7100 you get more more clarity and detail from 24 Mp Sensor.
Advance AF System in D7100
The D7100 features Nikon’s professionally proven and lightning-fast 51-point AF system, with a new Multi-CAM 3500DX AF module of Nikon D300. For additional precision, 15 of the 51 AF points are cross-type, and the center point is functional at f/8, giving DX photographers an additional telephoto advantage when using a teleconverter.
With Nikon D7100 you get ISO 50 to 25600, so without OPLF the images explode with more clarity and detail to take full advantage of the 24.1-megapixel resolution sensor.
You get more range with Nikon D7100
Continuous shooting Speed
D7100 is more fast compared to D5200
Nikon D7100 features big 3.2″ high res display unit.
Only D7100 features Environmentally Sealed Body
Rapid Response and Operation shutter lag is nearly imperceptible with a release time lag of 0.052 second (CIPA).
1.3x Crop Mode – innovative mode, shooters will gain an extra telephoto boost (2X), and a boost in burst speed to seven fps, with 15.4- megapixel resolution.
Conclusion – Winner Nikon D7100
- Nikon D7100 have no Optical Low pass filter
- Bit Broad ISO Range
- Advance AF system
- More shutter range and Fast top Continuous shooting speed
- 1.3X Crop mode
- Better Display
- Rugged Design
Nikon D7100 will cost you more but features excellent core specification for semi-pro or pro users.