Moving to 4K - Sony AX100 vs Panasonic GH4?

Started Feb 3, 2014 | Discussions thread
jkoch2 Senior Member • Posts: 1,198
Re: Moving to 4K - Sony AX100 vs Panasonic GH4?

Lab D wrote:

james b norman wrote:

THe AX100 also has much better and faster continuous AF for video.

I don't see how you can say that since the GH4 is not out yet.

As of this date, none of the people annoited to receive pre-sales versions have posted any clips in original condition shot by either the AX100 in XAVC-S or the GH4 in any of its assorted 4k formats.  When tests or sample clips do appear, though, I doubt we'll see any "shoot off" comparisons of AF of one versus the other, as least not for many months.  I'd wager that the GH4 AF will "seem" bad, mainly because the testers will use fast lenses and open apertures.  If everything is compressed to 1080p or lower, one might not notice a difference anyway.

The GH4 also has a new AF system that improves on the GH3 which was very, very good. Maybe you are talking about how the AX100 will have a very large depth of field?

The GH4 AF is probably very good for still photos, but we don't have any benchmarks for AF in 4k ivdeo.  Most existing 4k work probably relies on manual control and professional "pulling."

Most of the people who shoot video for cinema purposes advocate strongly for the highest possible bitrate, and berate the AX100 for having only 60Mbps rate for 4K...

Even for 1080/60p 60Mpbs is not great.

Its certainly on par with the best Blu-rays of Hollywood features.  Many average below 30mbps. 1080p on YouTube is barely 4mbps.

You always want the highest bit rate possible.

... forcing you to buy more memory and for all the advanced color grading you'll never have time or incentive to do.

Otherwise, no more true than when referring to gasoline consumption, vitamin intake, or blood levels of testosterone.  Only a few high-end ad firms or Hollywood studios have any tangible need or the requisite gear and specialists to utilize ultra-high bitrates or color sampling.  Exagerated codec spec is for naught if the lenses, lighting, stabilization, and editing resources are not also on par.

4k's most striking effect will be capture of details of relatively stationary shots.  Can anyone read a book that's moving around?  Quite likely, a mere 30mbps will be enough for a landscape with limited motion.  60mbps might be enough for moderate motion.  Fast or jerky motion will defy the eye's own ability to track details, unless one peeps at some little detail alone.

If 4k is compressed to 20mbs or less for streaming, it may not appear any better than HD, unless h.265 becomes widespread--perhaps by 2018.

I don't see any real comparison here.

True, no test comparisons available.  The early demo information won't tell much.  All manufacturers' demos are impressive.

The GH4 is more professional, will give you a higher bit rate and allow for shallow DoF. The AX100 is more of a family camcorder (and there is nothing wrong with that).

The AX100 is indeed more consumer-oriented.  Many people who buy the GH4 will decide to shoot only 1080p, after they find out the added hurdles and dubious yield of 4k, or discover that 10 bit 4.2.2 looks no different than 8 bit 4.2.0, after compression for streaming or conversion to 1080p.

Wonderful if Panasonic introduces a G7 or G8 (non "H") consumer m4/3 with a "4k Lite" of the XAVC-S sort.  Then an RX10ii and an RX100ii with 4k video.  This is inevitable, but perhaps not transpire before September, or be available before December.  Prices will come down.

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