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PatsGH2
25th February 2011, 02:42 AM
Hi all,
The other night I was trying to record my child's orchestra concert with the GH2 in movie mode. With the focus mode in either AFC or AFS, as I panned slowly across the stage, the camera would lose focus and hunt badly to regain focus. This was clearly not workable for a movie clip as the picture would become totally blurry with nothing recognizable for a short time. The only solution was to leave it in MF mode which basically defeats the whole hype about the camera sporting continuous autofocusing during movie taping.
Can anybody else share his/her own experiences? Am I doing something wrong?
Thanks
Patrick

thestickman
26th February 2011, 01:16 PM
There are 2 aspect to this:

First is the AF hunting. This is basically a factor of camera performance - it can be helped by having a larger focus zone, but completely unavoidable in some circumstances if using Continuous AF. To combat it - if you need Continuous AF, try to move relatively rapidly from one area with good contrast to another.

Second is camera / menu design. Setting AFS on the dial does not disable Continuous AF when shooting a Movie! What you need to do is go into the Menu, then the Movie settings page. Then scroll down to the second page to Continuous AF and set it to Off.
Once that is done - set the camera to AFS and shoot your Movie. You can half-press the shutter button at any point to focus preventing it from hunting as you pan.

Hopefully that will sort it for you.

PatsGH2
27th February 2011, 03:50 PM
This is just the information that I needed. It's probably in the manual somewhere that I missed. Thank you for this helpful explanation.
Best
Patrick

Auio
6th July 2011, 07:17 PM
The camera uses the "contrast" method of focus detection, which always displays some degree of hunting, and performs poorly in low light, sometimes failing completely. The other common method cameras use, "phase" based, employs special sensors to measure precisely where focus should be and goes directly there without hunting. I guess each has its advantages and disadvantages. The contrast method probably makes it easy for Panasonic to implement the touch screen focus rack feature, for example. Although I suppose the ideal camera could have both :)

Ian
6th July 2011, 08:25 PM
The camera uses the "contrast" method of focus detection, which always displays some degree of hunting, and performs poorly in low light, sometimes failing completely. The other common method cameras use, "phase" based, employs special sensors to measure precisely where focus should be and goes directly there without hunting. I guess each has its advantages and disadvantages. The contrast method probably makes it easy for Panasonic to implement the touch screen focus rack feature, for example. Although I suppose the ideal camera could have both :)

Phase detect is a range-finding system that uses a pair of beams split my prisms and semi-silvered mirrors. This can't be accommodated in a mirror-less camera like a Panasonic GH1. Ordinary camcorders use contrast detect AF as well and it's possobel to get hunting with these cameras as well.

Maybe what's needed is a focus limiter so that the AF stays within a set distance?

Ian

Auio
6th July 2011, 11:52 PM
Phase detect is a range-finding system that uses a pair of beams split my prisms and semi-silvered mirrors. This can't be accommodated in a mirror-less camera like a Panasonic GH1. Ordinary camcorders use contrast detect AF as well and it's possobel to get hunting with these cameras as well.

Maybe what's needed is a focus limiter so that the AF stays within a set distance?

Ian

Technically not correct. There are new implementations of phase detect in mirrorless cameras that use special sensors embedded in the main sensor. Using the mirror and beam splitters is just one possible implementation of phase detect.

WillCrockett
26th August 2011, 11:40 PM
One thing I have noticed on the GH2's autofocus system is that it does work unusually well - but only if you feed it with the correct info it's hungry for. Of course, the faster lenses help a lot (the 20mm f1.7 is strikingly good at low light AF) but you may want to experiment with the various AF modes and carefully match them to the shot you want it to make for you. I know that sounds over simplified, but use the Face Detection mode only with faces (duh right?) and ample roomlight for instance. Be careful with the single area AF mode as it is a little picky and it's hot zone is not as clearly defined as the viewfinder may suggest. Also, setup the AF / AE lock button to help you keep your focus "sticky" on one spot while you shoot more than one shot? Works great. I suspect that the vast majority of AF problems are actually caused by the camera being set with the wrong info - I know for sure than my AF problems are usually caused by me setting it up in a manner that is very different than the scene requires. Study up in the manual and practice when you can - it will pay off with nice sharp photos and video. Good luck!
WC

RobertD
27th August 2011, 01:28 AM
If you are shooting in iA mode the camera will always autofocus. You need to shoot in Creative movie mode M to set focus controls.

Cheers, Rob

WillCrockett
27th August 2011, 12:36 PM
Hey Robert, Right on sir! I look at the iA mode (and the new iA+ mode coming on the GF3) as the "ooops!" button. If I'm in a spot and notice a problem in taking a certain picture, it's usually due by me have some settings made for an earlier shot that I did not turn off. So, I hit the ooops button (the iA button) and bingo - the camera's smarts take over. But... I find that the iA modes tend to water down my photographic style and intent and result in sometimes a bland but correct shot. I use iA and iA+ only sparingly or when my wife wants to take a GF2 / GF3 for a spin she's all about the "purple button" on top. : )

rami sulieman
28th August 2011, 01:22 PM
is GH2 worke AF withe 12-60 pl 25 1.4 50-200

PatsGH2
28th August 2011, 03:52 PM
is GH2 worke AF withe 12-60 pl 25 1.4 50-200

I believe that the GH2 will only work in autofocus mode with the dedicated micro four-thirds lenses.

rami sulieman
28th August 2011, 05:32 PM
i fell sow bad e-5 is Expensive and no full HD 1080
I desperately need to shoot the video it is very difficult to move to another system because the only user of this system in my region, I can not sell equipment that I will not get an appropriate price or even less than the appropriate
my ger
1-Olympus E-3 body + HLD-4 (Grip + 4 more batteries
2-Olympus Zuiko 12-60mm f/2.8-4.0 Digital ED SWD
3-Olympus Digital Zuiko 50-200mm f/2.8-3.5 ED SWD
4-Olympus 7-14mm f/4.0 Zuiko ED Zoom Lens
5-Panasonic Leica D Summilux 25mm f/1.4 for 4/3
6-Olympus EC-14 1.4x Teleconverter
7-Olympus FL-50R TTL Flash
8-olympus RM-1
9-olympus RM-UC1

Ned
28th August 2011, 07:38 PM
Do you have client requirements for 1080 HD? If not, then I would stick with the 720p. The files are so much easier to handle, and at a normal viewing distance the difference is imperceivable to the human eye. In other words, you'd have to stick your face up to the screen to tell the difference, and for that you're handling massively larger files, especially if it's 60fps Interlaced as opposed to 30fps Progressive (interlaced needs the double frame rate to avoid seeing the interlacing effect).

I totally understand the need for 1080 HD due to the public opinion that 1080 is so much better and is "full HD" while 720p "isn't full HD". Therefore, many clients who don't really know the difference demand 1080 Full HD. However, if clients don't demand it I would not shoot 1080 of my own free will. Not unless they're doing all the post-processing...

If you're willing to shoot 720p HD, then your choices expand to not only the E-5 but also the Olympus PEN series (I wouldn't buy any Panasonic but the GH series for any real video requirements, as the rest don't have external mic jacks - all PEN cameras except the E-P1 do) if you can learn to use manual focus. As long as you want to use manual focus, then you can even get the newest generation PEN (ie, E-P3 or E-PL3) which now have 1080 HD video as well, and it should still be cheaper than an E-5, even with the EMA-1 mic adapter. (SEMA-1 with included microphone is about $100, but the EMA-1 with just the external mic adapter will be a lot cheaper... if it's available in your area).

Honestly, if you really want to get into video in a serious way then you should learn to use manual focus and get away from Auto Focus. No professional video camera I've ever used has the option of AF, only the cheap camcorders do that. And no video camera I've used can do AF as well as a cheap camcorder either, but excel in smooth operation of manual focus and zoom rings on the lens. Interchangeable Lens System Cameras such as DSLRs and MILs which have video functions are meant to be operated more like a professional video system rather than a consumer level camcorder. Otherwise, what would be the point in shooting video with your expensive high-quality lenses? Manual control of video will give you much smoother transitions and professional quality video, rather than the home-made jerky camcorder look. AF on a still camera never works well in video... only consumer-level camcorders seem to have any half-decent AF function, but that choppy AF (as well as the power zoom) doesn't compare to the quality achieved with Manual Focus on a professional-level video camera.

RobertD
28th August 2011, 10:06 PM
I have the olympus 14-54mm with adaptor and it works fine for autofocus/ and exposure. I believe the 12-60mm should be the same.
Cheers, Rob

Bif
23rd April 2012, 06:04 AM
Another factor that complicates autofocus is the typical lighting level for concerts and stage productions is often lower than it looks. The camera operator is often using the telephoto end of the zoom where autofocus will more easily tend to "hunt", the stage lighting may not be bright enough, and continuous autofocus only works with lenses that have that designed in, also requires constant light pressure on the shutter button to work.

So with all that considered, manual focus may be the better way to go.

Bruce Foreman

Janosch1408
21st May 2012, 05:28 PM
My trick is - if i use a zoom lens - mount it on a shoulder rig or tripod and hold the camera with the first hand on the zoomring and the second hand on the focusring, so when you zoom in you can adjust the focus at the same time. its not easy but not much more difficult than the normal MF...