The GH7 is the first model of the GH line to feature Phase Detection Autofocus. This is probably the single most important feature for the underwater shooter and therefore I have thought of putting together this post to give my impression from shooting the camera both at wide angle and macro.
There will be a separate post on image quality to see how the camera performs and how far the files can be strecthed.
Please note that the camera focuses differently in video than it does for photos and therefore you should not draw any conclusion for video autofocus from this post except that due to phase detection the infamous DFD pulsing no longer occurs.
The GH7 is physically identical to its now phased out predecessor GH6 therefore the housing fits both the GH6 and GH7. I sourced a second hand Nauticam GH6 housing from my friend Pietro Cremone of Fotosub Italia. The GH7 uses the same Nauticam trigger as the GH5/6 series.
General Autofocus Settings for the GH7
If you look in the menu nothing has changed from the previous Panasonic cameras.
You have a choice of focus areas as follows:
- Tracking
- Full sensor
- Vertical
- Zone
- Single Area + (includes anything touching the focus area)
- Single Area (limited to subjects fully inside the focus area)
- Pinpoint
Pinpoint is only available for single autofocus and subject detection can be enabled for any zone. The camera can recognise humans, animals, motorcycles, cars, trains and aeroplanes. The Animal setting has a body only mode in which case it will detect multiple animals and eye and body in which case it will detect one animal. This detection method works with fish and if you want to use it I recommend animal body only for wide angle and eye body for fish portraits. What has changed inside is that now for continuous autofocus the camera uses phase detection while single autofocus still relies on Panasonic DFD which is a sophisticated contrast detection method. The camera defaults to single autofocus in low light and clearly indicates this in the display so that if you need continuous you know it is time to turn on your focus light. I did not get this indicator in open water once.
One issue I have is that the joystick is not available through the housing so I needed to set a button to highlight the focus area and press the arrows to move it when I needed it. This is a considerable handicap compared to the A1 which topside does not exist as the camera has a joystick that unfortunately the Nauticam housing cannot control.Not many Nauicam housing have a joystick but Sony full size bodies, Canon and Nikon top of the range do.
To resolve this and make operations quicker you need to customise your camera for underwater use. Change the joystick to Fn and assign focus area to the joystick. This will allow you to skip one step compared to focus area select where you need to navigate to access focus area.
 [D.FOCUS Movement] / [Fn] / [MENU] / [OFF] |
| Sets the joystick movement on the recording screen. [D.FOCUS Movement]: Moves the AF area and MF Assist. (  AF Area Operations, Record Using MF)[Fn]: Operates as Fn buttons. [MENU]: Operates as  . Operations that can be performed by moving the joystick are disabled.[OFF]: Disables the joystick. |
You then go to the Function Button set up and set Fn9 to Focus Area Set.
Macro lenses tend to focus hunt and take a long time to move from infinity to your focus point, this is a problem in any format unless you use a focus limiter. The challenge when using a limiter on the lens is that in most cases once the camera is inside the housing and you have made a choice you cannot change it during the dive and therefore miss photo opportunities when the subject is outside your range.
The GH7 however has a software focus limiter feature that is extremely useful. You can set the focus between a near and far point and the camera will increase the focus speed significantly afterwards. This is also very useful to make sure that you do get close to fish.
You can assign this feature to a function button to quickly turn it on and off.
For the purpose of my tests I did not use this feature as I wanted to stress the setup and thought of using it only if I had problems but I did not. I find this feature invaluable to ensure you get really close. I have discovered when using wet diopters that all the wet lens was doing was forcing me to get closer but indeed I could have used the naked lens to get the same shot. In consideration of the limited depth of field I rarely use wet diopters with dedicated macro lenses on micro four thirds as the imaging frame is as small at 17.3×13 mm in size.
One thing that may be worth for close up is to customise the AF settings, there are 4 different sets of parameters you can use and you can also customise the AF to be near or far in addition to recalling the focus limiter with a button.
In the future I will need to check more the tracking without subject detection that can be useful in some cases where the camera does not find a subject, however using a large single area and the cursor I could cover all shooting situations with no issues.
Wide Angle with the Canon fisheye 8-15mm
Let me start by saying that I am not a fan of shooting fisheye lenses with Continuous Autofocus as the depth of field is high and the focus range is so limited that rarely it matters.
With the GH7 I use the Canon fisheye 8-15mm using a metabones adapter and this in the past only supported single autofocus. I noticed some vignetting on the bottom side of the frame that I did not experience with the GH5 series and I need to double check but otherwise the setup is identical to what you see here on this website.
Metabones released firmware V4.10 on 12 July 2024 declaring continuous autofocus compatibility with the Panasonic G9M2 which has indeed the same AF system of the GH7.
The update also improves general performance. The link in case you do not have it is here.
I updated my adapter and I can confirm continuous autofocus works correctly with the Canon 8-15mm. Like it does with the Sony camera the focus is a bit wobbly however it works fine. Yet my preference unless you shoot a fish portrait with the fisheye is to use single AF.
I used zone focus with subject detection, the GH7 does recognise fish and fish eyes so it did not have problem locking onto this grouper.
Fish was not always recognised, especially in those cases where only one eye was visible and the fish was on busy background, however the MFT camera combined with the 8-15 means there is always depth of field to fix any issues of focus at wide angle. A better option is to use animal detection without eye focus especially for schooling fish.
As I said before this was more academic so in the following dives I switched to single autofocus for wide angle because it is faster on the metabones, I do the same on the A1. The GH7 focussed very well. Few shots for illustration of the already known superb image quality of the Canon 8-15mm combined with the GH7.
Close up work with the Panasonic 45mm Macro
For close up work I use the PL 45mm because it has the best rendering on the MFT landscape. Here I used continuous autofocus by norm using a single area or zone.
I have been advised by Panasonic not to use tracking functionality however topside tests indicate it may work ok underwater. Many people get confused between tracking and subject detection so it may be worth some explanation. Tracking works with or without subject detection and allows you to choose an area on the frame that may or not correspond to a detected subject and then the focus points follow this area. It is especially useful when the camera does NOT detect a subject. Subject detection works differently: it uses the camera live feed to scan for shapes using a deep learning algorithm when a shape is identified the location of the focus points is passed to the autofocus engine to take the shot. Strictly speaking the camera is not tracking an area of choice but detecting one or multiple targets across the frame. This has a risk when there are multiple targets as the camera may jump from one to another however in close up work this is not generally an issue. If the camera detection works there is no need to use tracking as the subject detection mechanism is quicker and more effective.
I activated subject detection with Single Area + and the camera identified all fish with eyes, in my case groupers, gobies and blennies. For nudibranchs I got a shape around the body most times. The subject detection for fish is way more successful than my A1 but I do not know how it compares with the latest implementation of the A7R V that has more detection modes like insect that may be relevant.
I took 255 shots in a dive with the 45mm of which 5 did not have a subject in focus and of those 2 had no subject as the fish had run off the frame.
For Macro you may want to activate auto review for 0.5 seconds, now this allows you to see where exactly the camera focused.
The Panasonic PDAF system focuses like a DSLR with the lens wide open. This is different from other mirrorless systems like Sony or Nikon and it means that when you stop down the lens the camera takes longer to take the shot and can potentially have focus shift, this is mitigated by the significant depth of field of the cropped format.
I had a very high success rate as mentioned and only in a few circumstances the focus was off the eye but more because the fish had moved too quickly and I was at close range.
This focus system is excellent for shots wide open and you can easily obtain nice bokeh with eyes in sharp focus.
Subjects like nudibranchs can move fast or be on little algae that is swaying in the current, the MFT system with the huge depth of field available means you can achieve the effect you want easily. Different shots at various f stop
The GH7 like the GH5 and GH6 can sync with the strobes at 1/400 using the Nauticam trigger which also supports rear sync. This is a value only the A1 can match and is very useful for close up work as it easily gives you dark backgrounds in the right conditions.
Take into account that the depth of field even at f/11 on MFT equivalent to f/22 on full frame is 1 cm at close range therefore some really small critters may even need f/16 or more.
I did not have a single shot with focus on the background which for me is quite impressive.
The 45mm maintains good sharpness even at f/10 and further but I did not stress the set up in my tests.
I had a focus light but I never had to turn it on because the GH7 focuses wide open, my strobes have a pilot light but this is only useful if you aim at the subject which in most cases I actually do, again there was no need to use it.
Conclusion
The Panasonic GH7 performs very well both at wide angle with a dome port and at close range with a macro lens. Continuous autofocus is reliable and appears to work fine without a focus light even when the shooting conditions are not easy. Subject detection recognises fish and fish eyes and makes shooting easy. The only remark is the lack of joystick control on the Nauticam housing that would make it even easier to work with single area focus, the operation is still possible but requires two button presses. I would trust the GH7 as much as I trust my A1 with the reservation of very dark environments that I did not have time to test.
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