We finally got to dive our GH4; here are some thoughts and video:
Our diving is mostly in California in water that often contains particulate matter, as well as being somewhat deep and dark. Our previous camera (HF-G10) had quirks that manifested in our local environment (especially green water) that took us quite some time to figure out. We’ve been encouraged by the results we’ve seen others achieve with their GH series cameras in environments like the ones we frequent.
Our dive site was Ship Rock at Catalina Island in California. This location offers a deep wall area at 150ft/45m and deeper, as well as progressively more sunlit kelp garden type areas to explore on ascent- a perfect spot to play with the camera in a variety of settings.
The rig as we dove it:
Lumix 7-14mm lens
Nauticam NA-GH4 housing
6” Acrylic dome port with focus knob
Keldan Luna 8 lights on UL arms
The objective given the lens was to shoot wide shots and not really attempt Macro. We have discussed the idea of being able to fake “semi” macro with this lens by zooming in to 14mm and then cropping to 25% at 1080p. But that will probably look funny considering the FOV. We will attempt that stuff later when we have the quadpod fitted. Mainly we shoot wider angle anyway and aren’t too concerned with macro at this stage. Being reasonably confident that resolution would be outstanding, we were mostly concerned with low light performance, edge distortion on the Lumix 7-14mm/Nauticam dome combo, attaining sharp focus to take full advantage of the UHD, banding when shooting against open water, and how to set up the camera.
For this dive the camera was set to
Cine-D picture style (hoping to gain a little in low light given the lens is not so fast)
Custom white balance at depth on blank pages of wet notes; auto WB in the shallows.
UHD resolution at 29.97p
Picture style settings set to
Pedestal at 0
Highlight/shadow at zero
ISO manual (between 200 and 400 trying to avoid noise)
F stop between 4 and 4.5 on the deep portion, stopped down to 11-22 as needed in the shallow area.
Shutter speed at 60
Focus using the partial shutter depress method
We began recording at 150’ after white balancing with lights on using white pages of wet notes. This has been our method with our previous camera; one diver holds wet notes open at a distance of 3-4 ft from the camera and the camera diver zooms in and sets white balance. The goal is to white balance not for the fully lit foreground, and not to try to correct the un correctable colors beyond the lights at this depth. The Lumix 7-14 is so wide even at 14mm that we couldn’t fill sample area with white from our usual distance, and had to move the wetnotes within about 2 ft of the camera. The GH4 only samples a rectangle in the middle of the frame, so this helps this distance problem somewhat.
Noise was visible immediately on the camera monitor, keeping in mind we are already at ISO 200. Not having time at depth to mess with settings, we simply proceeded with recording. The noise turned out not to be as big an issue as it appeared (see below). As far as exposure goes I was actually pleasantly surprised that even with an f/4 lens there appeared to be enough light between the Keldans and ambient to not need to raise the ISO much at all. The little monitor on the back of the GH4 is very bright and sharp, and it was much more accurate with regard to color and exposure than what I had been used to with our L&M Bluefin monitor from our previous system. Not perfect but ok. The Nauticam housing with the plastic dome is also much less negative in the water than the L&M, which was a nice bonus. With no flotation added the rig was still easy enough to swim around. This being basically the first real dive with the camera combo, all the controls were easy to use and we had no problem effectively using the housing with dry gloves on.
Video from the deep portion of the dive:
Video from the shallow sunny portion:
All told we found the capabilities of the camera in these conditions very satisfying.
Things that made us happy:
Low light performance was fine for our needs.
Noise in the UHD image easy to remove with neat video. Since the NR is occurring at UHD resolution and the video is output to 1080p, I could see no loss of detail in the final image. I don’t have a 4k monitor so I can’t see if there is a visible difference at that resolution, but for my purposes Neat Video almost magically removes the noise with the only side effect being some occaisional micro banding, which can be eliminated by building a more complete profile in neat video.
Great detail all around
Shutter depress focus method was able to focus effectively on the target 90% of the time. Would not attempt to use continuous auto focus however unless the scene was very well lit. Will experiment with manual focus/peaking on later dives.
Battery life was never in question. Over three hours in the water with camera on and still had two bars.
The footage allows for much more latitude to adjust color and exposure (and obviously framing) than the AVCHD from our HF-G10 did. This was a surprise but a pleasant one. This became important because the settings we chose made a flat, somewhat noisy image that needed to be adjusted to be presentable.
Banding is almost a non-issue. If there is banding visible in the video we uploaded, it is a product of Vimeo compression and doesn’t appear at all in the source footage.
With the 4k crop, the edge distortion we’ve seen from this lens is reduced and often not visible at all. Hopefully trying slightly more stopped down/slightly higher ISO combo will eliminate it completely.
We can make nice looking video with this camera. As we learn the camera the footage will only improve.
Things to work on:
We need to black out the printing on the front edge of the lens; when shooting into the light the lettering can sometimes be seen reflected in the dome port.
Settings. Our settings produced noise. As we had it configured there was very fine grain over the whole image. Even in the bright sunlight at 20fsw, there was visible noise in all the images. Since ISO is already low, I believe we need to make adjustments to the other settings in the camera. I have read that Cine-D profile is a known source of noise. Going forward we will be trying Cine-V. More tweaking is needed before we arrive at our known-good configuration.
UHD files play fine on my Macbook Pro, you can cut and edit no problem, but if you need to apply an effect- such as Neat Video- everything goes in to snail mode. This is not a deal breaker but it is a reality if you have an older laptop (mine is a 2011). I need a new one anyway.
Some edge distortion visible at 7mm f/4.
For our first time using a “photo” style camera for video, we were very pleased.
Edited by textilet, 07 September 2014 - 10:14 PM.