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Member Since 25 May 2005
Offline Last Active Apr 17 2015 03:12 AM

Topics I've Started

Tracking focus with a GH4 in the NA-GH4

04 April 2015 - 06:19 PM

Caveat: Maybe you all know about this technique and find this thread a bit "ho hum".  In which case, please ignore.  But, for me, it was an exciting breakthrough that improved my success rate shooting moving subjects.




Panasonic GH4 in a Nauticam NA-GH4 housing with either the 7-14mm, 12-35mm (dome) or the PZ 14-42mm (flat port) shooting video of octopus, cuttlefish and squid in Lembeh.  I wanted to be able to shoot these critters "up close" and "on the move" but still keep them in sharp focus.




I don't trust any auto-focus tracking system and have not had reliable success using it with the GH4 underwater, especially in murky conditions.  I prefer to use AFL/AEL to lock in focus and exposure for the whole clip.  With the camera set to AFS and a small centre focus point, I lock in the focus on the eye of the critter at the start of the clip.  But, then the critter starts to move.  How do I ensure that the critter's eye stays firmly in the narrow depth of field?  Obviously I need to move the camera with the subject, keeping the distance between the critter's eye and the lens at the same distance.  But that's quite difficult, especially checking the focus with the small monitor on the back of the GH4.


Solution 1 (attach a better monitor):


Use a large monitor that has built-in focus peaking like the Shogun.  But, Nauticam have not yet released the Shogun housing.  And I need to get the footage now.


Solution 2 (flip on the GH4's focus peaking): 


Unfortunately, the GH4's focus peaking only works when the camera is set to manual focus (Panasonic: could this be fixed in a firmware update, please).  The lens / port combinations that I'm using don't have manual focus.


But (and here is my big breakthrough), the NA-GH4 housing has a MF-AFC-AFS switch in a convenient location.  


Here's what worked: Before diving, turn on focus peaking in the camera's menu and save it to your favourite UW custom setting.  Underwater, set the MF-AFC-AFS switch to AFS and use the rear lever to set AFL to get a sharp lock on the subject's eye.  Flip the MF-AFC-AFS switch to MF.  The lens stays at the same focus distance as locked in.  But now the subject is also covered with focus peaking dots.  As the subject moves, move the camera with the subject, ensuring that the focus peaking dots continue to flicker all around the subject's eyes.  


If it's not moving too fast (e.g. an octopus walking), I was able to keep the subject firmly in the plane of focus (9 times out of 10)...




Sign the Change.Org petition for Bangka Island in Indonesia

10 January 2015 - 06:15 PM

I don't know if online petitions have much impact or not but maybe, if enough people sign it, the central government in Jakarta may pay attention.


Places like Bangka Island are unique and increasingly rare. We must save them for our children and future generations.

Anyway, I just signed the petition "Gov. @Sarundajang2014 & Bupati Sompie Singal: No mining on small islands. Save Bangka – North Sulawesi!" on Change.org.

It's important. Can you sign it too? Here's the link:



Video Light Filters

21 December 2014 - 02:31 AM

I mentioned in an earlier thread that I had been experimenting with some video light filters with the objective of finding a better balance between underwater ambient light and the broader (red) spectrum of artificial video lights.  Here is the problem, obvious in the screenshot below: the area covered by the video light has a lot of warm colour (reds and yellows) but the background is all greenish-blue.  Colour-correcting this scene is either a compromise or a complex exercise of selective secondary colour-corrections.


Attached File  No Filter.png   131.01KB   19 downloads


I think that I've found a cheap DIY system that can solve this problem and can be tuned to most underwater ambient light circumstances.


The main component is a 4x4 filter holder made by Lee Filters.  It's all plastic and rubber so nothing to rust. $20USD each at BH Photo: http://www.bhphotovi...4x4_Filter.html


Here is the holder with an aqua filter (the same filter that I used in the shot further below)


Attached File  IMG_1032.JPG   110.3KB   19 downloads


The slip-on rubber-band mounting system enables it to fit on most underwater video lights.  I use them on a pair of iTorch 7s but they also fit the Keldan Luma4s.


Here is folder mounted on the iTorch7.  It can be "wriggled on" easy enough and will not easily fall off - although I do take them off when getting into and out of the water so that they don't get bumped off.


Attached File  IMG_1030.JPG   108.1KB   19 downloads


The filters are pieces of plastic that I cut from document folders that I bought in stationery shops.  I wandered around a few shops until I had found a mix of light blue, dark blue, aqua (green-blue) etc. The firmer document folder covers work best.  I also cut some uncoloured plastic squares that are a neutral colour but make a nice diffuser for softer macro lighting for night dives.


You can take a few different shades of the colour filters on each dive but I find that I can usually judge from the surface what I will need.  The technique is simply to look at the colour of the water and select a filter that is the closest match.  If the water looks tropical blue, use a blue filter; if it looks greenish, use an aqua coloured filter.


So, here is the result.  This is the same scene as above, shot with the aqua filter on both lights then quickly colour-corrected in FCPX to reduce the green and boost the reds.


Attached File  Aqua Filter - Corrected.png   428.46KB   21 downloads


To my eyes, this image is very close to what it looked like underwater last week in Lembeh.

(the coconut octopus inside the drink bottle is guarding eggs and in the last few days of her life).


I have also used the same system in the deep blue waters of North Komodo, where a light blue filter worked best.


So for $40, some time wandering around stationery shops and a little bit of scissor work, you can make a video light filter system that will enable you to balance ambient and artificial light in most situations.




Results of my first commercial shoot with GH4

17 October 2014 - 08:32 PM

Here is an example of a GH4 video that I've just finished editing: http://www.peterwalker.com/komodo.html


It demonstrates the camera's capabilities both WA (7-14mm lens with Zen 170mm dome), Macro (14-45mm PZ plus flip Subsee +5 dioptre) and above water (12-35mm plus polarising filter).  I did all the editing in 4K and then compressed to 1080P just before uploading to Vimeo.


It was a pleasure to shoot and edit!





Thanks to David Cheung of ScubaCam for helping put the equipment together for me.

Panasonic GH4 Settings for Underwater

08 August 2014 - 02:13 AM

Setting up a GH4 for Diving
To a lot of you who’ve been shooting video with DSLRs for some time, the settings on the GH4 might be a bit “ho hum”.  But, for me, shooting camcorders for the last 10 years, it’s been a sea-change.  I spent a lot of time studying the settings and came up with something that works for me.  I thought that I’d share it.
Firstly, I have to say that I prefer a “natural” look; I like my finished video to look as close as possible to what my eyes saw underwater.  So that "natural look" bias is in my settings.  I don't WB to white or add a lot of red.  You can adjust to your own tastes.
Secondly, when I am underwater, I want to focus as much of my attention on the “story” and the “subjects”. But I rarely use an “auto-everything” approach as that does not work well in many situations.  But, I do like to quickly get to as close to the "optimal look" without too much fiddling and adjustments (while the whale shark swims away).
So, I have found it very useful to leverage the custom setting feature in the GH4.  It works really well with this camera.  After a lot of research and testing, once I had an idea of what I needed, here is the process that I used:
  1. Set all the “in menu” settings (my preferred settings are below)
  2. Set the camera controls to your most “usual” setting
  3. Set the WB presets (more on how to do this below)
  4. Save this to C1 (in my case, C1 is full manual)
  5. Without changing the menu settings from C1, change the camera settings to your second most “usual” settings 
  6. Save this to C2  (in my case, C1 is shutter of 1/50 with AFL/AEL for focus and exposure)
  7. Change to your third most “usual” settings.
  8. Save this to C3-1 (in my case I use “shutter 1/50; auto-everything-else”)
  9. (you could do two more settings, C3-2 and C3-3, but I don’t use these because they are not so quick to access)
GH4 "In Menu” Settings
Tool Menu:
Personal choice but set date, time and system frequency first, I use 24.00Hz
Motion Picture (set dial to motion picture):
Cine D (flat - good for grading)
Contrast 0 (neutral)
Sharpness -5 (none)
Noise Reduction -5 (none)
Saturation 0 (neutral)
Hue 0 (neutral)
Rec Format Mov (less compression)
Rec Quality C4K 100M 24P (as many pixels as possible)
AFS/AFF: AFS (half-press focus)
Continuous Auto Focus Off
Highlight/Shadow: Flat diagonal line
i.Dynamic Off  (don’t want it to mess with the CineD profile)
i.Resolution Standard (does some selective sharpening)
Master pedestal 0 (neutral)
Luminance level 0-255 (full range - can limit later in editing)
Synchro Scan Off (used for shooting TVs and monitors)
Ex Tele Conv Off
Digital Zoom Off (just crops the image)
Time Code Off
HDMI Rec Output 10bit 422 (eady for the Shogun)
Info Display Off (Shogun has its own)
4K Down Convert Off  (No thank you)
Sound output Realtime (only relevant for monitoring sound with headphones)
Silent operation On (tries to keep zooming quiet)
Mic Level 0db
Mic Limiter Off (no auto sound gain)
SS / Gain Operation SEC/ISO
Color Bars SMPTE
Custom Settings Menu:
Cust Set Mem - here is where the Custom setting (1, 2, and 3) are saved.
Silent Mode On (no lights or noises inside the housing)
AFL / AEL Lock - Off for Manual custom setting, Both on for other two settings
AFL / AEL Lock Hold - On (locks it until you unlock it with another press)
Shutter AF On
Half Press Release Off (not good inside a housing)
Quick AF Off (wastes battery)
Eye sensor Off (does not function inside a housing)
Pinpoint AF Time - Mid (does not seem to matter)
Direct Focus Area Off
Focus / Release Priority - Release (not relevant to video)
AF+MF On (allows fine manual adjustments of focus)
MF Assist On (the lens barrel) -(expands the manual focus part of the monitor)
MF Guide Off (personal choice)
Peaking Off (personal choice)
Histogram on (and moved to bottom-left corner)
Guideline - Grid On (personal choice)
Center Marker Off (don’t need a grid and a marker)
Highlight Off (Histogram is better)
Zebra 1 Off Zebra 2 Off  (Histogram is better)
Monochrome Live View Off (want to see the colour)
Constant Preview On (not relevant to video)
Expo meter On (for manual exposure guide)
LVF Disp Style - text over image (larger image in VF)
Monitor Disp Style - text over image (larger image in monitor)
Monitor Info Diaplay On - see the settings
Video Priority Display On (gives more data for video shooters)
Fn Button Set - I changed Fn1 to Auto Focus On but don’t use it - still finding a use for Fn1
Q.Menu - no changes
Dial Set - no changes
Video Button On (but I always use the shutter button anyway)
Eye Sensor - High / Mon (don’t use it - always use Monitor)
Touch Settings - all Off - can’t access them in a housing
Touch Scroll L - irrelevant as settings are Off
Menu Guide Off 
Shoot w/o lens On - doesn’t matter either way
My GH4 Underwater WB Presets:
WB1: Light Blue
WB2: Mid Blue
WB3: Light Green
WB4: Mid Green
Kelvin: 6500K
How to do the WB preset?  Print 4 A4 sheets of paper filled with the four colours above.  (I have attached my pdf files). Set the camera to C1 to load up your custom settings.  Place the first A4 sheet (light blue) in a natural light (sunlight - not artificial light as this would introduce a different colour cast).  Open up the WB set function for WB1, point the camera so the colour fills the image and set it.  Do the same for the other 3 papers into WB2, WB3, and WB4. Go to the Custom Settings menu and “save” (overwrite) the C1 settings.  Now the WB presets are locked into the camera.  You can change the WB settings underwater but you can always get back to the presets by simply moving the mode dial.  Do the same for C2 and C3.
Then, when you are diving, use:
AWB: for near the surface and when video lights dominate (cave / night)
Kelvin 6500K for 5 meters down to 12 meters
WB1 for 10 meters to 20 meters  (in tropical blue water)
WB2 for below 15 to 20 meters (in tropical blue water)
WB3 for 10 meters to 20 meters  (in green water)
WB3 for below 15 to 20 meters (in green water)
The depths mentioned above overlap because you need to make a judgement call, depending on the conditions.
My GH4 “Usual” Camera Settings, saved in Custom 1, Custom 2 and Custom 3, respectively.
  1. M; ISO 200; f2.8; 1/50s; AFS, centre-area focus - this setting is for when I really want full control over everything, even using manual focus if necessary; great when you have time to get a shot really right
  2. S; ISO 200; 1/50s; AFS, centre-area focus - this setting is for when the aperture is not so important and I want to quickly do an AFL / AEL lock before shooting than have the camera hold those settings, quicker than Manual but fast enough for most situations
  3. S; ISO Auto; AFC, multi-zone focus; multi-zone exposure; +/- set to minus one notch - this setting is for when something happens fast. e.g. a big creature swims past, and you don’t have time to think - flip the mode dial to C3 and let the camera do its best to figure it out. Shutter is set to 1/50.  Camera will adjust Aperture and ISO to get a good exposure.  +/- reduced to avoid the camera trying to make the image too bright.
Might all look a bit complicated, but, if you set this all up once, you don’t need to do it again unless you want to make some adjustments.
Underwater, it is very simple:
Use C1 if you want manual control
Use C2 if you want to use a focus lock and exposure lock (NA-GH4 has a handy lever for this)
Use C3 if you want the camera to do everything for you
Then depending on your depth and the conditions, flip the WB setting quickly between AWB, Manual, WB1, and WB2.  (or WB3 and WB4, if the water is green)
The other upside of this C1, C2, C3 approach is that, if you have been fiddling with any settings, a quick flip of the mode dial gets you back to a known state.
I hope that this is helpful.