I see... then are there any alternatives to the GH2 and gh3?
Hi Kaisheng. You did not specify what sort of videos you will be making so I'm going to recommend based on your interest in the GH2 and GH3. What makes these two cameras very, very, very special is that they DO NOT have a 30 minute recording limit in video mode. You can record a clip for as long as your memory card has space or until the battery dies.
If that is the main reason for choosing the GH2 and GH3, then you will be happy with a GH4 , GH5 , the FZ2500 or the BlackMagic Pocket Cinema. Other cameras recently on offer in the marketplace section that have no recording limit are the Panasonic AF102 and the Sony VG900 camcorders. But note that these camcorders are much larger than mirroless/DSLRs and will not fit on single grip gimbals.
Personally, I loved the GH2 because of it's size. So much so, I was willing to overlook many of its shortcomings.
Today, the closest (but better) 'clone' of the GH2 is the Canon EOS M5. Let me explain:
Size and feature wise the GH2 and the EOS M5 are almost identical.
The M5 has all the video features of the GH2 except for "unlimited clip length"
Neither has a headphone port which I feel is their single biggest weakness.
But where the M5 wins is Canon's Dual Pixel Autofocus.
DPAF is the most tried and tested autofocus system in video today and works brilliantly on the M5.
The M5 also has very powerful electronic image stabilisation when you use an autofocus EF, EF-S or EF-M lens. (will not work with manual lenses)
If you enjoy shooting handheld, you will love the IBIS. In combination with lenses with optical stabilisation the result is nothing short of 'tripod-like'
The only time when I wished I had bought a Canon EOS 80D instead is when I want to record audio but the M5 does not have a headphone port.
That said, the 80D does not have the M5's EVF and the E-IBIS function. So that is a big toss-up between the M5 and 80D.
If you shoot a lot of interviews, the 80D will be the better choice.
Again, my recommendations are based purely on conjecture and I'm curious to know what ar the real reasons for your interest in the GH2 and GH3.