Read:

ALLWAYS SHOT 60P since you can post process to 24p 30p 60i 48p or whatever you want. Footage may look "videoish" in movement, since cadence is not like 24p, but then you can allways post process.

If doing slow mo in post prosses always doit on 60p is the most data you can get from sensor. If doing slow mo in camera, you may loose some data, that in post will not recover, in 60p you will.

So best recomendation:

For general purpose: 60p For slow mo or fast mo in camera: timelapses or special cases. For standar "cine" like cadence 24p

If you want slow motion w/the GH3, you can shoot in 1080/60P and slow it down in post or use an in-camera method that says "slower" ("faster" speeds things up).

When shooting, use a shutter speed of at least 2x the frame rate. For example, when shooting 60p, use a shutter speed of 1/120 or more (1/125 being the closest you can get on most current cameras).

I believe all of the in-camera slow/fast modes (40%-300%) create a 1080/24P file.

The bottom line

Shooting 60P will give you more control in post (more frame rates you can playback cleanly to), but will require some amount of post-processing and you'll have to wait until you ingest the footage and conform it to see what the slow motion end result actually looks like. Most NLEs will be able to conform 60P footage to a different frame rate (24, 30, etc.) without any rendering or interpolation, but the methodology varies based on the NLE being used.

Shooting using an in-camera slow/fast mode will allow you to see the end result immediately after shooting, but you have less control and flexibility when it comes to post production. The motion is basically frozen as is unless you fancy interpolation and rendering time.

You can always play the videos back in slow motion in camera by hitting pause during playback and then holding down the right arrow button. It will play in super slow motion.

Never use the in camera slow motion modes. There is no reason to give up sound.

NLE = Non Linear Editor

Quick question (kind of on topic)

I use Cinema Tools to conform my 60p footage from my GH3 to 24p to use in FCP. Most of the clips i am shooting i want in slow motion, but some of them I want to play back in real time. I have just been changing the speed to compensate but sometimes it just doesn't look natural.. Is there a better way to do this?

in camera frame rate adjustments do not record audio at all