Amendments after additional tests:

With a dummy battery, the screen flipped out, no active cooling, and a normal ambient room temperature, a 4k60 4:2:0 10-bit recording overheated the camera sometime after 3 hours.

The same setup WITH Ulanzi active cooling, a 4k60 4:2:0 10-bit recording ran indefinitely with no heat warning.

TL;DR

I spent a week performing a lot of G9 II overheating tests, and am presenting the results here. The quick summary: There are some things you can do to prevent the G9 II from overheating, but they have their own pros and cons. Ultimately, if you want to record tons of video without any overheating, you should not buy a G9 II, and should instead spend the extra cash on a GH7.

Full test parameters and results are below. Before continuing, a disclaimer: A few links in this blog post are affiliate links to the exact products I actually purchased and tested with. Clicking on these links don’t cost you any extra money, but may earn me a small commission.

Background

I shoot primarily long-form video: Product photography, talking heads, and events. I am invested in the micro four thirds (M43) lens system, and bought a Panasonic Lumix G9 Mark II as soon as I was able to afford one, because I really wanted the first Panasonic M43 camera with phase-detect autofocus. It works great, and the autofocus is finally fantastic — however, it overheats during longer video shoots, shutting down video recording functions for 13 minutes to recover.

What’s worse, I bought it at the worst possible time: 35 days before they announced the Panasonic Lumix GH7, which doesn’t overheat. 5 days past the return policy, it was too late to return my G9 II for a refund. If I try to sell it on ebay, I can expect a $600 loss. So I guess I’m stuck with it.

Trying to make the best of a bad situation, I decided to see what the overheating limits are, so I let the video recording run as long as it could in different resolutions, framerates, colorspaces, and codecs. The results are below, and I hope they are helpful to someone.

Test Setup

Almost all my shots are locked down on a tripod, so that’s what I used for these tests. I have been shooting 4k exclusively since 2016, so I didn’t bother with smaller resolutions. I didn’t test any ALL-I modes because I haven’t used them since Panasonic added h.265 to their cameras (and ProRes to the G9 II). I also didn’t test true DCI 4K (4096×2160) modes, as I felt UHD 4K (3840×2160) was the more common use case.

Here are the test parameters I adhered to:

• Indoors at room temperature (roughly 70F/21C)
• On tripod
• Screen was flipped OUT. (Very important!! This exposes the back of the camera to release more heat!)
• Used “dummy” battery connected to mains/wall power
• Heat management was set to “high”
• Recorded to 2 x 128G v90 SD cards mirrored (128G total storage). Cards were reformatted between each test.
• 1/60 shutter (to match room lighting frequency) for all 60p/30p/24p modes
• Waited until back of camera was cool to the touch before starting a new test
• All recording formats were h.265 (LongGOP). Colorspace was 4:2:0, as I didn’t notice any significant heat differences between 4:2:0 and 4:2:2 during initial testing.
• Times reported are the lengths of the resulting footage files, truncated to the nearest minute
• All recording modes were the full readout of the sensor, with the exception of the 4.4k modes which are a 1:1 pixel crop
• All tests were performed three times, and the median value chosen as the result

128GB Mirrored v90 SD Card Results

Resolution	Framerate	Behavior	Length	Notes
HD (1080p)	240p	OK	1h27m	240p not a typo; this high-framerate mode is used to shoot slow-motion footage
UHD 4K	24p	OK	1h54m
UHD 4K	30p	OK	1h54m
UHD 4K	60p	OK	1h27m	Flashed heat warning after 50 minutes, but did not stop recording
UHD 4K	120p	overheated	23m
4.4K (4:3)	60p	overheated	41m	This is a 1:1 pixel readout/crop
5.7K (17:9)	24p	OK	1h27m
5.7K (17:9)	30p	overheated	45m
5.7K (17:9)	60p	overheated	33m
5.8K (4:3)	24p	OK	1h27m	Full sensor readout / “open gate”
5.8K (4:3)	30p	OK	1h27m	Full sensor readout / “open gate”

I was very surprised the 5.7k 17:9 (5728×3024) 30p mode overheated much faster than the 5.8k 4:3 (5760×4320) 30p open gate mode, as the full-res open gate mode processes more information per frame. I have neither explanation nor theories for this behavior.

Do larger/slower SD cards help with overheating?

To see if shooting long-form events were possible, or if slower cards caused more (or less) issues, I used larger+slower SD cards to see how far I could push the camera. I saw no significant differences in overheating performance doing this. Modes that overheated still overheated at roughly the same length. Modes that previously worked continued to work.

For example, recording to UHD 4K 60p filled a 512G V30 SD card with 5+ hours of video. As in the previous test, this also flashed a heat warning around the 50 minute mark, but it kept going and filled up the card.

Does an ULANZI Camera Cooling Fan help with the overheating?

Yes. Mini-review:

The ULANZI Camera Cooling Fan is a $40 battery-powered add-on fan with two speeds and a temperature display that attaches to most mirrorless cameras designed with a flip-out screen. I bought one and connected it to continuous power (only fair, since my camera was on dummy battery continuous power as well), set it to high speed, and re-tested the modes that previously shut off due to overheating. Results:

Resolution	Framerate	Behavior with fan	Old limit	New limit with fan
UHD 4K	120p	overheated	23m	23m
4.4K (4:3)	60p	OK	41m	58m
5.7K (17:9)	30p	OK	45m	1h27m
5.7K (17:9)	60p	OK	33m	58m

So, the Ulanzi fan definitely helped extend the recording times in most modes that had overheat shutoff issues.

That said, there are some caveats to using it:

• Mine did not stay connected to the G9 II very well; it kept sliding down, then flying off at great velocity because of the spring-loaded nature of how it attaches to the back of the camera. I added four small adhesive rubber “bumps” to all four corners to permanently solve this issue.
• The fan is not silent, and raises the noise floor picked up by the camera’s microphones to -30dB. (That said, nobody uses the built-in camera audio for anything serious.)

Does writing ProRes to an SSD help with overheating?

Not really. The only video mode that overheated that also had a ProRes equivalent was 5.7K (17:9) 30p, so “prores as a way to generate less heat” is only useful in one recording scenario. Not only is this a very narrow limited scenario, it still overheated. Writing to an SSD led to a max recording time of 64m (prores) vs. 51m (h.265).

For SSD testing, I used a cheap but fast M.2 USB-C enclosure with an older 256G M.2 NVME card I had lying around.

Does using an external recording monitor help with overheating?

Yes. I used an Atomos Ninja (newer version, not the Ninja V) as the monitor + recorder for the G9 II, as I had purchased it earlier in the year for an unrelated project. In all recording scenarios, I was surprised to see the G9 II heat up, even though it wasn’t recording! But despite that, it never fully overheated and stopped, even when displaying the flashing heat warning.

The highest RAW resolution and framerate I could achieve with my Ninja (the Ninja Ultra can go higher) was 5.7K 30p. Where the native camera overheats and shuts off at 45m using that resolution and framerate, using the Ninja resulted in no overheating and filled a 2TB SSD with over 3.5 hours of ProRes RAW footage.

Recommendations and Conclusions

While I’m stuck with my G9 II, I was happy to see that some demanding modes such as UHD 4K 60p and 5.8K 30p can record nearly indefinitely at normal room temperature. For other demanding modes that overheat, at least I now know what they are and can plan accordingly.

Please keep in mind that these numbers were the result of optimal indoor shooting conditions. If you’re shooting outdoors with direct sunlight hitting the camera, or you shoot with the flip-out screen in the closed position against the back of the camera, you can probably expect 1/3rd (or less!) of these runtimes, and should buy a GH7 instead.