Category Archives: Panasonic GH7

autofocus, Dome Port, dynamic range, Equipment, Flat Port, housing, Micro 4:3, Panasonic GH5, Panasonic GH5M2, Panasonic GH6, Panasonic GH7, Underwater Photography, wide angle

Panasonic GH7 Review for Underwater Photography – Image Quality and Housing Ergonomics

August 21, 2024 interceptor121 14 Comments

This is my second post on the Lumix GH7. After discussing in detail autofocus which was for me top priority I want to cover more in detail image quality and ergonomics.

Image Quality

The GH6 was not a step forward in terms of image quality from the GH5M2. I have owned all the models GH5, GH5M2, GH6, GH7 and from a photography point of view the pinnacle has been the GH5M2 which was a more significant step forward from the original model most people think. I have provided test data to photonstophotos for all the follow up models and this graph summarises the situation when it comes to RAW PDR.

What this tells you is that both the GH5M2 and GH7 are a step forward from the original GH5 while the GH6 was an improvement only from ISO 800. Considering that underwater on micro four thirds you will always be shooting ISO 100-200 the GH6 was not really adequate for photo performance. It is true that the GH5 has been really the target of video shooters however GH stands for Hybrid cameras and the series has been made of models that could do very good video and photos. The GH6 was really a video beast the GH7 that has the same body is back on the GH5 tradition of top performing hybrid camera.

A few key improvement over the GH5 include:

Increased resolution 25 Megapixels vs 20.2
New RAW files with 16 bits depth
Dual Gain Output Circuit
Back illuminated sensor

The GH7 does have some interesting topside features like the ability to record pre-burst images and reach 60 fps with continuous autofocus but those are more for the bird shooter and not applicable to underwater use. Panasonic declares that image quality may drop for shutter speed slower than 1/15 at ISO 100 and therefore this should be your slowest setting also underwater. I do not see this as a limitation even for panning shots.

Many users confuse resolution and megapixels. Spatial resolution is computed on a single dimension in line per millimetre. Therefore the increase in resolution compared to the GH5 and GH5M2 is only 11.4% (5776/5184) this is not exactly life changing but more pixels are always better than less pixels bearing in mind that pixel size and image overall noise are NOT related.

With regards to the dual gain output circuit the increase in peak dynamic range compared to the GH5M2 is only 0.3 Ev (10.17 vs 9.87) and is entirely due to the fact that base sensitivity is now ISO 100 instead of 200.

In the ISO range between 200 and 2500 the GH7 is not better than the GH5M2 and from ISO 3200 it gets better in virtue of noise reduction. Again we are never going to shoot ISO 3200 underwater so this is for us of limited interest.

Perhaps the most interesting feature of the GH7 are the new 16 bits RAW files.

A typical wide angle image has a size of 38 MB which is rather large considering the 25 Megapixels, for reference Sony A7 IV files are around 42 MB. There are several discussion about the efficiency of Panasonic compression but we are not going to go and deep dive on this. What matters to use is how much beating the raw files can take.

Modern cameras exhibit peak dynamic range when underexposed 3 stops from a grey card (I know this sounds strange but is a fact). The way to assess how much beating a file can take is to select one image where your strobe did not fire or was too weak for the situation and increase exposure three stops and see the resulting image.

This is an underexposed image as an example where I had forgotten to turn up the strobes.

This is the image applying +3 exposure and other corrections.

The camera can easily take +3 adjustment as well as shadows up to 100% which is an excellent result.

The other aspect of image quality is of course the lens and we can here use the excellent canon 8-15mm in the entire zoom range.

Compared with my A1 in a similar shot I can say that at the edges the GH7 is superior and in the centre the difference in actual resolution is small to non-existent despite half the pixels.

This is because the lens shot at f/16 drops considerably in resolution compared to f/8 which are the equivalent apertures in full frame to micro four thirds. The files are full resolution I let you do the pixel peeping.

This resolution chart shows the underlying reason when the lens goes from f/8 to f/16 looses 30% of the resolution. Taking into account the smaller pixels of the GH7 this could mean an additional drop to the point the images are indeed very similar.

All in all the RAW files of the GH7 can take a lot of beating without issues as long as you do not clip the highlights like any other camera.

In general terms I feel the RAW files of the GH7 are similar in handling to my A1 and A7C II.

Housing Ergonomics

Lets’ first cover the drawbacks of the Nauticam housing.

As mentioned in the autofocus post the housing does not give you access to the joystick which is a drawback. There are other two issues with the housing, the handles are angled forward, something typical of the Nauticam GH series that I continue not to understand. Why would the GH5 be any different from other cameras?

Not all function buttons are accessible in particular the two on the left side of the camera are not. Those are to be fair not the most important buttons and there is already a variety of buttons and controls available so except the joystick there will not be an issue underwater.

The lever under the front ring controls the function buttons 2 and 3 that correspond to the front two buttons of the camera.

I recommend using one for constant preview, hitting will circle through aperture simulation, shutter simulation or nothing and the other can be used to recall the focus limiter which is very important for macro shooting as explained in the previous post. The function button on the back can be your fn 9 to recall the focus area movement useful if you want to move it.

In total you have access to 3 function buttons as well as white balance, ISO, exposure compensation, focus mode, operation lock, EVF/LCD, quick button, menu and the four arrows, delete, mode, shutter mode, playback, movie, af on so there is nothing really missing.

FN button instead of joystick control can be used to move the focus area

One very important feature is that the handles position can be adjusted, I move out the left handle so that the lens is central to the handles, on my A1 I needed to buy an extension as the port is closer to the left handle.

The housing also has an M10 accessory port as well as the ability to host M5 like the A1, and two ports for monitor and vacuum valve in addition to a cold show

While nauticam recommends the M5 accessory personally I find the cold shoe and especially the M10 port more suitable for focus light and external monitors.

One awkward thing is the N120 to N85 adapter port has the release on the bottom of the camera but that is not a housing issue yet something to bear in mind. The housing is not small at 331x176x136 with a weight of 2.8 kg is indeed similar or equal to a full frame camera.

The final consideration is that the price of the GH6 housing that is compatible with the GH7 is very high, more than a Sony A7 IV, less than Sony A1 and way more than other smaller micro four thirds body as well as other full frame (the S5II housing costs less).

Who is the GH7 for?

The Panasonic GH7 is without a doubt one of the most capable hybrid mirrorless cameras on the market however due to the housing price is unlikely to be attractive to the masses. If you are cost conscious you can get the OM-1 for less due to the smaller housing, if you want performance several full frame cameras will incur similar cost. The real strength of the micro four thirds is the lens choice. You can cover everything with the Canon 8-15 or if you prefer with the Tokina 10-17 there are many wide and macro lenses and the huge depth of field means everything will be consistently sharp across the frame. The real strength of the GH7 though is hybrid use, if you want a camera equally capable of top range photos and videos you are looking at Sony A1 or Nikon Z8 or similar or the GH7 and here it becomes interesting for the latest Panasonic. In the near future I will provide some details of how the GH7 performs as a video capture device.

autofocus, Canon EF lens, Equipment, Fisheye lens, Flat Port, macro, Panasonic GH7, Underwater Photography, wide angle

Panasonic GH7 Review for Underwater Photography – Autofocus

August 16, 2024 interceptor121 3 Comments

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.

[SELECTING AF MODE ]

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.

[Joystick Setting]

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.

[FOCUS LIMITER]

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.

[AF SETS]

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.

The GH7 focus right on the eye of this large grouper

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.

macro, Panasonic GH7, Underwater Photography

In support of Depth of Field

August 11, 2024 interceptor121 1 Comment

The debate between resolution and depth of field is even more relevant today with the discontinuation of DSLR and the rapid growth of Mirrorless cameras.

I have been a mirrorless user since 10 years now and I am pretty familiar with the benefits and disbenefits of the system.

One of the main disbenefits I have found especially when moving up to the Sony E-Mount full frame system has been lack of depth of field in close up shots.

While the Canon RF and Nikon Z mount still allow apertures of f/32 on their macro lenses, the Sony 90mm Macro only goes up to f/22. This is indeed a serious limitation for macro shooting. The reason is unknown but all Sony E-mount lenses stop at f/22.

It may be that this is related to the loss of resolution due to diffraction.

On full frame sensor the diffraction limit is reached around f/20 however resolution starts to drop much sooner. Also consider that effective aperture of macro lenses is much smaller due to changes of the effective focal lenght, angle of view but this applies across the board and I do not want to make this post more complicated.

This is a resolution chart produced by lenstip for the Sigma FE 105 Macro. You can see that the resolution drops from a stellar value of 80 lp/mm at around 28 lp/mm at f/22, the lens has lost 65% of the peak resolution that was reached at f/4.

Depth of field however does matter in close up photography and has been one of the reason why I have recently invested in a Panasonic Lumix GH7.

Panasonic GH7 with 45mm macro in Nauticam NA GH6 housing

In the title image you see an example of shallow depth of field on a blenny. That image is shot at f/2.8 on the GH7 which is f/5.6 on the sony FE system and the depth of field is extremely thin.

I have taken some test shots using a ruler here the entire series on the GH7 from f/2.8 to f/22.

The fly is 4 cm long starting from f/2.8 and focusing between the eye you can see looking at the ruler that only few mm are in focus despite the frame is around 9cm so no even macro.

At f/4 the lens reaches peak resolution however the depth of field is still very small we can barely read the numbers on the ruler behind the fly.

By f/5.6 we have more depth of field but not enough to focus on the front antennas.

At f/8 we start seeing the back of the fly but it is not all in focus.

By f/11 the whole head antenna included is in focus but not the whole bug. And here if we were on the Emount full frame the story stops.

We continue to f/16 which sees the focus arriving to the wings. This is as far as you could get with the Nikon and Canon mirrorless.

Finally we hit f/22 equivalent to f/44 on full frame and not available on mirrorless the fly is in focus front to back.

What is not apparent in this set of images is how much resolution has been lost stopping down the lens.

To give more precise indication I shot a 10 cents euro coin of the diameter of 1cm.

This image has got more magnification and is almost 1:1 on micro four thirds. At f/2.8 we have practically a bit more than 1mm depth of field.

At f/4 peak sharpness of the lens the detail is great but the depth of field is still very limited perhaps 2.5 mm.

We keep going until we hit f/8 and later f/11

Not even at f/11 we have the whole coin in focus and we start loosing xy resolution due to diffraction.

f/16 is probably the best compromise for such high magnification image.

f/22 has the whole coin in focus however the resolution has dropped.

Yet if we need it we have our high depth of field scenario.

A few other examples at full frame 1:1 with frame width around 36mm.

The f/11 scenario equivalent to Sony 90mm f/22 has depth of field of around 1cm or less

By f/16 we are hitting around 2 cm.

Finally at f/22 we have 3cm depth of field more or less.

I was recently diving in Italy let me show a few examples of what this means.

This flabellina is focussed on the head however as it is turning slightly away from me part of the body is soft. You would argue the head is what matters but lets’ continue.

At f/5.6 the nudibranch is more horizontal the shot is well in focus however you can only see part of the head.

By f/8 we have it sorted consider that this is a small nudibranch not very deep laying almost on the focal plane.

This is instead paradoxically more difficult the nudi is flat on the sea bed however the body parts come into the camera so there is a risk of running out of depth of field here I stop down to f/10.

With the focus point on the back the bottom right under is not sharp!

Here other examples at f/10 where you can see the depth of field is not sufficient to cover the fish.

larger fish do not make necessarily things easy as in the example of this grouper.

At f/5.6 the fins are soft similar shot at f/10 improves the fins but does not cover the body.

Now you would ask why did I not go all the way to f/16 or f/22 simply because I wanted to simulate the limit of the Sony FE camera I have.

The other interesting fact is that if we look at this very old resolution chart for the Panasonic 45mm taken with a 12 megapixels Olympus E-PL1 we see that at f/11 equivalent to the f/22 of the sigma the lens hits 55 lp/mm.

This value is likely to be higher wit the GH7 that has double the pixel count indeed exceeding 60 lp/mm.

Comparing the Sigma 28 lp/mm * 24 mm frame height gives 1344 LP/PH while the Panasonic is giving 1560 LP/PH. Which means the smaller sensor seems to resist better to stopping down making it more suitable to high depth of field photography and one of the reasons why I acquired a GH7.

The problem historically with Micro Four Thirds was that autofocus even in the Olympus implementation was far behind and the camera could not track subjects. This is to an extent still true however the GH7 and OM-1 have powerful subject detection. The GH7 in particular can detect fish bodies and eyes.

In my last shots the camera would focus right on the eye on slow moving subjects. Fast moving subjects at high magnification were a few mm off but overall easy to compensate with the extra depth of field.

Conclusion

We are a times, me included, obsessed by resolution charts and pixel count and forget that images have depth. A good image needs to be tridimensional and depth of field is essential to achieve it in some cases even more important than absolute spatial resolution on the focal plane.

Micro Four Thirds cameras were historically lagging on autofocus due to weak tracking and this is to an extent still true, although the camera tracked fine my swaying in the water, however subject detection able to recognise fish means that the gap is essentially closed and overall you can produce a significant amount of good images without risk of blurred shots.

For information the GH7 like the GH5 syncs at 1/400 with the nauticam trigger and for wide angle rear sync is supported which gives another advantage to this micro four thirds camera over other formats, only the Sony A1 syncs that fast

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