I am new to photography and am confused about high speed flash. If u have an external flash, set it manually, can I take pictures with flash faster then 1/200 with the D5200?I know it doesn't support high speed sync (which is stupid) but if it's done manually instead of TTL... Will it work?
No, we are limited to 1/200 second with flash. Does not matter if manual or TTL flash, internal or external flash.. This is a limitation of the focal plane shutter itself. At speeds faster than 1/200 second, the shutter would not be fully open to allow the flash to illuminate all areas of the image plane. This is called Maximum Sync Speed.
More detail and examples at
Four Flash Photography Basics we must know - Maximum Shutter Sync Speed
But realize that it is the speedlight that stops motion, not the shutter. For example, the SB-700 flash has these specifications for flash duration (SB-700 manual page H-17)
1/1042 sec. at M1/1 (full) output
1/1136 sec. at M1/2 output
1/2857 sec. at M1/4 output
1/5714 sec. at M1/8 output
1/10000 sec. at M1/16 output
1/18182 sec. at M1/32 output
1/25000 sec. at M1/64 output
1/40000 sec. at M1/128 output
This can stop a tremendous amount of motion. Faster than any shutter.
The other Nikon speedlight models are about the same speed (called Speedlights).
See
Capability of flash units for high speed photography for the idea... using low flash power for incredible speed, up close in dim light, at any slow shutter speed (in dim light where it doesn't matter).
FWIW, some other models (like D7100 and up) have mode called Auto FP that can kludge around this, with drastically different action, but with only about 20% of the power, and no speed stopping ability. Another subject.