G7 and G85 AutoFocus while shooting video questions

red sled wrote:

pannumon wrote:

red sled wrote:

Thank you pannumon. I was almost ready to purchase one of these two cameras but the focus difficulties others were having has given me pause.

I'm not familiar with these AF difficulties as I normally shoot with a Nikon D90 or D300s which I see have phase-detect AF for normal shooting. Perhaps, as you say, it would get better with experience trying different settings.

Are we talking about stills AF or video AF? Because G7 and G85 will be way ahead of any Nikon DSLR when considering video AF. Also the whole "live view" experience should be a totally new world when using a system that is built on top if it.

When it comes to stills singe-point AF (S-AF), Panasonic cameras should focus much faster than you Nikons. Considering continuous AF (C-AF) or tracking focus, expect the Nikon DLSRs to be better (by far).

When shooting video, unless you actively tell the camera where to focus (either by touching the screen or half-pressing the shutter release button), any camera will have difficulties to know where you want the focus to be, or when to refocus. This can be controlled semi-automatically (much like using A or S mode instead of fully automatic mode for stills).

Thank you pannumon for your patient explanations. Originally I was asking about video AF. I did not realize my Nikons used a different AF for video. Interesting, and that explains why I rarely use them for video as it can be very frustrating because it "hunts" a lot while filming and seems to be out of focus frequently.

After much consideration, I believe the majority of work for this new purchase would be scenery, both 4k video and also time-lapse video in 4k (preferrably) or 1080. Would you still recommend the G7 vs. G85 , or some other model ? I would love a GH4 to grow into but can't swing it at this time. I really do like the Panasonics for flexibility and options for time-lapse in the camera .

The Nikons use CDAF when recording video, not PDAF (they don't have on sensor PDAF like some newer Canon DSLRs). While the Panasonic also use CDAF, their CDAF is much more advanced and when using compatible lenses it will also offers DFD (in AF-S it is just as quick as PDAF), which is even better.

I have a D5000 so I can relate to the frustrating Nikon video experience. My GX85 is a ton better in video AF and video in general. G85 will be even better given it supports DFD 2.0.

As for the two cameras, if budget is not a problem, I would strongly recommend the G85 for video work. The IBIS is a game changer for video and allows you to have stable video without a tripod (G85 has Dual IS 2.0 so even better than my GX85). OIS alone simply can't match. The weather sealed 12-60mm it comes bundled with also gives a nice range and gives you a whole weather sealed package (given G85 is weathersealed, while G7 is not).

If you worry about hunting, you can set the AF so that it only refocuses when you half press the shutter button (just turn off Continous AF setting). AF is very fast when doing this (I use my GX85 this way). AF does slow down when recording 4K though vs 1080p. Continuous AF is going to be slowest.

If you are going to use it unattended and need Continuous AF, set your aperture to a sufficiently deep DOF and it shouldn't really hunt. Set a baseline focus point before pressing record. The main people complaining about continuous video AF are vloggers who may be moving back and forth from the camera a lot and they need reliable AF without having to monitor it.

The G85 does have an AF sensitivity setting that allows you to prevent hunting in AFC mode (p211 in advanced manual).

ftp://ftp.panasonic.com/camera/om/dmc-g85_en_adv_om.pdf

You asked about single point AF in video. I presume you mean where it is set to center or you get to select the point. If so, yes the G85 does support it. It supports every AF mode in video that it does in stills (see p93 for all modes). There is a ton of customization available in video (remember to set the mode dial to the Creative Video Mode p85).