Lumix GH3 Review Part 6 Sport/Action

LUMIX GH3 REVIEW PART 6  SPORT AND ACTION

It does a better job than many reviewers realise

Author AndrewS  April 2013

Don't try this at home. GH3, 35-100mm lens.  This type of shot would be difficult for any AF system. The subject is backlit, the background is brighter than the subject which is only about 15 meters from the camera. The horse is galloping. The camera could keep the subject in focus at Burst Rate M up to about this point in the arena but as they horses got closer they became progressively less sharp.

Introduction    Mirrorless ILC's [MILC] use contrast detect autofocus [CDAF] taking data directly from the imaging sensor. DSLR type cameras use phase detect autofocus [PDAF] operating from a separate AF module located beneath the mirror box, or in the case of Sony SLT cameras up near the viewfinder. In the early days CDAF systems were slower than PDAF types, but the latest versions are very fast indeed with single shot AF.  Until recently however mirrorless cameras have had  difficulty achieving follow focus on subjects moving towards or away from the camera with AF continuous and  Burst/Continuous drive at several frames per second.

GH3 with 35-100mm lens. Hang Gliders are easy subjects to photograph as they glide gently across the cliff top. In AFC  the GH3 will get almost 100% of frames sharply in focus if I frame accurately.

MILC focus systems   Manufacturers have used various strategies to improve focus speed  for MILC's. Most  have designed completely new style focussing mechanisms in MILC lenses utilising direct, low friction electro magnetic drive of the focussing lens group. This allows the lens focus to be racked back and forth at a much higher speed than was the case with previous technologies.   Another strategy, used by Canon, Nikon, Fuji and Sony, has been to allocate some 10,000 or so pixels on the imaging sensor to PDAF. The idea is to use the PDAF function to bring the lens quickly to near the correct focus point then locate the exact point with CDAF on the same sensor. From reports, this technology appears to have been implemented successfully by Nikon with the 1 Series, with the other makers to a greater or lesser extent playing catch up at the time of writing.

The conventional wisdom has been that CDAF could never match PDAF for sport/action use. However the Lumix  and Olympus M43 cameras have stuck with CDAF and are in fact making significant progress with follow focus capability.

GH3 with 35-100mm lens. This subject was handled easily by the GH3. This is one of a burst of 13 frames, all but the last few with the cars very close to the camera, were sharply in focus.

Note on "AF Tracking" often referred to incorrectly in user forums as "Focus Tracking"

Readers please note: There is much confusion about this in user forums.  There is no option called "Focus Tracking" in the lumix M43 Menu list.

AF  TRACKING  IS NOT THE SAME AS FOLLOW FOCUS

AF Tracking is a specific AF Mode in the GH3 and other  M43 cameras. In the GH3 it is selected via the [Fn3/AF Mode] button. The other AF Modes are Face Detection, 23 Area, 1-Area and Pinpoint.  It refers to a technology by which you ask the AF system to remember a specific subject element in the frame, such as a person's face,  your pet dog, or whatever, and continue to maintain focus on that subject element when it moves laterally within the frame. If you are really lucky your dog might stay in focus as it moves towards or away from the camera as well.

Follow Focus  This is a term which I use. It refers to the process by which the camera's AF system can sustain focus on a subject moving towards or away from the camera, using AF Continuous and Burst/Continuous Drive Mode. In this case it is the operator's duty to keep the active AF frame on the chosen subject to ensure the AF system is following the desired subject.

This article is about FOLLOW FOCUS   

I do not use focus tracking as it relinquishes to the camera an essential aspect of control over the focussing process which I want to keep myself. That is: On which part of the frame do I want the AF system to focus ?  I would be quite happy if the Lumix product team quietly dropped  "AF Tracking" from the list of AF Modes.

Readers please note:     The term "Follow Focus" does not appear anywhere in the Lumix list of focussing options.

It is the term I  use in connection with the process of autofocus on subjects moving towards and/or away from the camera. I always use and recommend setting [1-Area] AF Mode for this purpose.

I suspect that many of the adverse reports about this camera's AFC performance may have been due to the reviewer having set AF Mode to [AF Tracking] in the mistaken belief that this was appropriate.

Successful follow focus depends on optimal setup, preparation, technique and practice.

GH3, 35-100mmm lens. Large, steadily moving subjects in bright sunny conditions are managed easily by the GH3. Over several sequences totalling 50 frames, one was unsharp. 

Setup

Rec Menu

Page 1,

* Photo Style--Standard (only applies to JPG)

* Aspect Ratio--Any, I usually use 4:3 which provides the most opportunity for post capture cropping which is almost always required.

* Quality--Any. I use RAW. The GH3 has a fast procesor and big buffer which makes RAW capture very possible. Previous M43 cameras with slower processors and a smaller buffer required JPG capture for a sustained burst.

* Metering--Multiple.

Page 2,

* Burst Rate-- M or L.  M is the fastest rate which provides Image Preview [Live View]  on every frame.  The camera will focus on each frame at Burst Rate H but preview on each frame is  lost. Burst rate L obviously gives less frames per second but in many situations is quite adequate. The advantage of Burst Rate L is that the ratio of  Live View Time to Blackout Time is higher which makes the subject easier to follow in the EVF.

* i-Dynamic and i-Resolution--Off. You want to relieve the camera of any unnecessary data processing which would slow down frame rate performance.

Page 3,

* E-Shutter.    Burst Mode and AFC work with E-Shutter on however I usually leave it off because of the "rolling shutter" effect which can cause distortion with moving subjects or a moving camera and you will generally have both with sport/action.

Page 5,

* Shading Comp--Off

* Color Space--Adobe RGB

* Stabiliser--On--Standard

* If you are shooting JPG you can select Ex.Tele Conv or Digital Zoom here. Ex. Tele Conv works best as it allows full control of the position and size of the active AF area. Note that Ex.Tele Conv only works if Image Size is set to M (Medium, 8Mpx) which gives 1.4x, or S (Small, 4Mpx) which gives 2x.

Page 6,

* Face Recognition--Off.

GH3, 35-100mm lens. Same situation as the top photo.  Both frames are cropped.  I got about 50% of these sharply in focus which I consider a very good result in the circumstances. 

Custom Menu

Page 1,

* AF/AE Lock--AF-On. This allows the operator to start AFC with the back button if desired.

* Shutter AF--On

* Half Press Release--Off

Page 2,

* Quick AF--Off

* Eye Sensor AF--Off

Page 3,

* Direct Focus Area--On

* Focus Release priority--Focus.

Page 4,

* Histogram--Off

* Expo Meter--Off

Page 5,

* LVF and Monitor Style--Set to the style which places main camera data in a black strip beneath the preview image. You do not want anything cluttering up the preview image and you do need to monitor the shutter speed in particular without the distraction of having the data readouts overlaid on the preview image.

Page 6,

* Auto Review--Off.

Page 7,

* Eye Sensor--Auto. Some people prefer to have direct control of the EVF and prefer manual switching using the LVF/Fn5 switch.

* Touch Settings--Off.

GH3, 35-100mm lens. Pilot and photographer doing it easy.

Disp Button  Cycle this until the preview image is clear of all camera data. You need to have clear view of the lens aperture, shutter speed and ISO in the data strip beneath the preview image. The only items overlaid on the preview image are a minimal two line grid, if desired and the active AF area square.

Drive Mode Dial--Set to Burst.

Main Mode Dial-- Set to P or S. Depending on the lens in use and the subject a shutter speed of 1/500sec or faster will usually be required.   Another possibility is to make a Custom Mode setting after all the camera settings for Sport/Action are in place.

Focus Mode lever--Set to AFC.

Auto Focus Mode (AFMode/Fn3Button)--Set to [1-Area] Not AF tracking

ISO-- Usually set to Auto, however if you have set P Mode there may be situations where Auto Iso does not give a fast enough shutter speed in which case you will need to set a high ISO manually or switch to Shutter Priority Mode or both.

White Balance--Auto

Exposure Compensation--Usually nil. However there may be situations such as ice or snow when exposure compensation is required.

Preparation 

This is a camera user review not a camera use tutorial, however readers are advised that the follow focus performance of the GH3 or any other camera is highly dependent on user preparation and skill. Aspects of preparation include:

Lens Selection  Some lenses, particularly older ones operate more slowly than newer models. By this I mean they deliver a slower frame rate for any given camera settings. Presumably this relates to slower AF and aperture diaphragm operation. The Lumix 100-300mm OIS is unfortunately about the slowest I have tested which is a pity as it would otherwise be a first pick for sport/action. It is quite suitable for subjects which move fairly slowly and steadily in good light, such as board surfers. The Lumix 35-100mm f2.8 is faster but obviously suitable for a different subject profile due to the wider angle of view. The Lumix 45-150mm runs decently fast.

Shutter Speed/Aperture/ISO   When preparing to make action photos run some preliminary frames, keeping a close eye on your shutter speed and aperture. Make sure the ISO is high enough to give adequate shutter speed. The keeper rate will increase if you use an f2.8 lens at f5.6. So the camera focusses at f2.8 and captures at f5.6 for a bit more depth of focus.

Check the Light and the Background  All autofocus systems of any description look for areas of the frame with high brightness and/or contrast. Try to take a camera position to locate the light source behind or on one side of the camera and try to avoid bright/cluttered backgrounds. As you might expect AFC works best in bright light with subjects having a high brightness range ("contrast").

Technique

Zoom in to frame the subject but not too tight. Once the action starts you need to leave plenty of room to cope with the inevitable variations in framing accuracy. View through the EVF. You need to hold the camera as steady as possible and exclude non subject distractions.

Adjust the size of the AF box so it is no larger than the subject. You can shift position of the AF box also but I usually leave it in the center.

Don't zoom during capture bursts. I have tried this but it appears to throw the camera off target.

Start AFC with either back button press or half press shutter button and hold this for half a second or so for the AF system to acquire target. Then start capture by fully depressing the shutter button and hold it down for the duration of the burst.

In many situations Burst Rate L will be perfectly adequate and is easier to use than M rate as there is a greater proportion of viewing time to blackout time.

Performance-- Speed

The GH3 with Lumix 35-100mm lens, RAW capture, AFC, Burst Mode M, giving Live View and AF on each frame, using a Sandisk 95 MB/sec card, will capture 28 frames in 6 seconds [4.6 fps] before the frame rate slows suddenly. If capture is stopped at this point, the buffer clears in 7 seconds.

With the same settings and  Burst Rate L  the camera will continue to shoot RAW capture at 2.8 frames/sec for 50+ frames without slowing. If capture is stopped at 50 frames the buffer clears in 8 seconds.

This camera has a much faster/ higher imaging throughput capacity than previous M43 cameras and has more capacity than most cameras of any description.

Performance--Accuracy

The percentage of frames sharply in focus  is dependent on circumstance and operator skill.

Here are some examples :

Subject	Lens	% Sharply in Focus	% Just unsharp	%Blurred	Comment
Cars accelerating 15-40 kph	35-100mm @100mm  f2.8	75	22	3	*1
Cars accelerating 15-40 kph	35-100mm @ 100mm f5.6	78	20	2.5	*1
Cars at 60 kph	35-100mm @100mm	90	8	1	*2
Cars at 60 kph	100-300mm @250mm	52	34	14	*3
Board surfers	100-300 @300mm	68	28	4	*4

Comments

*1. Closing down the aperure from f2.8 to f5.6 gave a slightly higher rate of frames sharply in focus.

2.  All frames had to be cropped after capture as each car was not large in the frame.

3.  This test was run from the same camera position as the one above. The 100-300mm lens had a more difficult task as all the cars were larger in the frame so the change in focus position from one frame to the next was greater.

4. On a bright sunny day most surfing frames will be sharply in focus.

General Comments:

Most of the out of focus frames are those at the end of a burst when the car or other subject has come very close to the camera such that the change in focus from one frame to the next is beyond the camera's capability.

See the photo captions for further comment.

Conclusion  The Lumix GH3 is a moderately competent sport/action camera. I would place it approximately at the level of upper entry or mid range enthusiast DSLR for follow focus capability.  There are many types of subject in motion which it can manage quite easily with a high percentage of frames sharply in focus.