Tag Archives: wet lens

Getting the best colors in your underwater video with the panasonic gh5

There is no doubt that the Panasonic GH5 is a very capable camera and in given conditions the video performance you can get is truly impressive.

Broadly speaking a video clip needs to be:

  1. Sharp
  2. Colorful
  3. Contrasty
  4. Clean

Those 4 characteristics are tightly related to:

  1. Resolution
  2. Color depth
  3. Dynamic range
  4. Low Noise

Resolution

Today everyone shoots 4K and after all resolution is well supported by almost any camera, broadly is unaffected by other factors and unless the noise is really high sharpness of your frame is not going to be a real issue shooting at 4K.

Color depth

In normal conditions and not underwater a camera can resolve many colors. However underwater due to the diffraction of light and selective absorption of colours the starting point is very different from land. So generally is not the camera that cannot resolve the colors but the colors that are missing to start with. This post will focus specifically on this aspect. The Panasonic GH5 can resolve 23.8 bits in RAW and therefore technically has less than 8 bits color depth – do not confuse this with the 8 or 10 bit recording setting.

Dynamic Range

Underwater scenes tend to have limited dynamic range, with the exception of sunbursts or shooting against the light this is going to be an issue only in specific circumstances of very bright scenes with shadows. In all scenes taken with video lights dynamic range is not an issue at all. The GH5 has 13 stops of dynamic range but rarely this is an important consideration.

Noise

Noise is an important consideration as when the noise goes up the camera looses the other characteristics, color, dynamic range and resolution will be affected when the camera is outside the sweet spot. Broadly speaking the Panasonic GH5 does not do well once you pass the ISO 1600 setting and I tend to cap the ISO in video at 800 in most cases.

Diving Conditions

To understand how those variables play we can see how the same set up reacts very differently in scene where there is less light and therefore the camera uses high ISO like this one.

The same camera with exactly the same equipment in brighter water produces this

So the reason for the above is that with less light there are less colours and the clip looks what it is really.

OK moving on to the main subject of this post how do I get the colors right? It is a combination of techniques and the trick is to use the right one in the right conditions.

Generally every site has specific conditions that change depending on weather, time of the day, visibility and other factors. So in broad terms a site will have more or less light and therefore more or less colours. It is therefore impossible to categorically define what to do at a given depth but is more about typical values. With this in mind we have typically 3 scenarios:

  1. Ambient light shots
  2. Artificial light shots
  3. Balanced light shots

Close up Shots

In general close up shots especially of small subject fall within the scenario 2 for which a video light with high color rendering is important as this will define the colours you see. With a lot of power it is possible to extend artificial lighting to larger subjects but eventually you run out of power due to distance or size of the subject.

Wide angle shots and seascapes

True wide angle shots are generally ambient light shots which also means when it gets too dark the colors will be missing and it will look blue not matter the equipment.

In order to make the most of ambient light shots for wide angle it is essential to balance the colours in water even when you use a RAW format on a still image because RAW files are not as RAW as you think and are actually compressed.

Custom White Balance

Using Custom White balance with a grey card it is possible to obtain decent results until the camera hits the maximum color temperature in the case of the Panasonic GH5 this is 9900K. Depending on conditions you may get to 10-12 meters and this still works, in darker water this stops working much sooner.

Chrisoula K Bow
Chrisoula K Ambient Light 5 meters

Color Filters

Color filters push the limit of custom white balance further down. Some add more or less 4 meters others up to 6-8 meters at the expense of an overall loss of light. Filters are useful when there is a lot of light because also help to keep the Panasonic Gh5 in the best aperture range (not smaller than f/11)

Filter in action at 10 meters

Right now there are predominantly 3 filters on the market:

  1. UR PRO
  2. Magic filter
  3. Keldan Spectrum

All those filters will improve the performance and color rendering of your footage, under the conditions that the loss of light is not pushing the camera above reasonable ISO values.

In terms of depth range the magic filter and the Keldan Spectrum -2 version can be pushed to 15 meters depth on a bright day in clear water. The URPRO is capable of getting a few meters more down to around 17-18 meters although it does generate an orange cast (as there is no red left) it is still workable.

FilterLight LossTypical Max Depth
Magic Filter1 1/2 stop15 meters
Keldan Spectrum -22 stop (WWL)15 meters
URPRO 2 stop18 meters

This image gives an idea of the 3 filters as you can see they are very different one from the other.

Keldan top URPRO bottom Magic filter

Balanced Wide Angle Shots

This is an entirely new technique that has started with the Keldan Ambient light filters. I wrote a whole piece on wetpixel

The principle is to use custom white balance with or without filter to obtain color rendering and then put filters on the video light so that the color of the light emulates the ambient light and therefore it only gives texture not color.

Keldan has developed a whole range of filters for various situation that match their light and therefore are not applicable to any other light.

As I do not own a set of Keldan I have done some tests and found that a gel of Cyan filter 2 or 3 stops makes my divepro G18+ practically ambient light in the conditions I dive into.

FilterCyan Strength
Magic Filter2 stops
Keldan Spectrum2 stops
URPRO3 stops

The above value are based on my experience use at your own risk especially with different lights.

Square Cyan 2 stops Round Cyan 3 stops

To give an idea I overlapped the filter to my iPhone lens

This is the shot without any filters

Original Shot

URPRO and Cyan 3 stops (darker)
Magic filter and cyan 2 stops accurate
Keldan and cyan 2 stops accurate

This example shows that the two filters cancel themselves the result is almost daylight with no cast which means in water if you use a video light or a strobe you will not see a red or orange spots on the image.

For those taking pictures the same combination remains true with Inon Z240 and Sea and Sea YS-D2

Example picture here

five in a row
My own filter and Cyan 3 stop note that the light is coming from the other side

One thing to take into account is that you need to find a way to hold the gel on the video light or the strobes. The flat surface strobe diffusers make this process easy, finding something you can use with your video lights is not easy and also the gels may melt after continuous use.

Artificial lights

It comes a point and a depth where filters stop working, this could be as shallow as 8 meters in green water. As the scene is dark using lights is what is required. There is nothing specific about this technique except making sure you don’t get burned highlights or backscatter. As it happens in photography using long arms (maybe not as long as for stills) is key to get good lighting on your subject.

My Camera Settings

I use CineLike D with saturation, sharpness and noise reduction to -5. I shoot at 24/25p AVCI 400 mbps and follow the 180 rules, it is entirely possible to shoot at 1/100 if you like more crisp look.

Clearly there are people out there that do not like filters and think white balance is best etc but I think a good read on magic filters explains it all.

http://www.magic-filters.com/need.html

Macro video with the Panasonic gh5

Broadly speaking with the GH5 as well as with any other camera you have four categories of close up work:

  1. Close-up – frame size 10 cm or 4″ and wider typically hand held
  2. Super close-up – frame size 5cm or 2″ preferably on tripod
  3. Macro – frame size below 2″ only on tripod
  4. Super macro – frame size below 1″

For still images a typical choice is the Olympus 60mm, this lens however is very narrow so for any subject that is not too small and for the first category of close up you end up having working distances well above one foot. This in turns means more water to go through and makes it virtually impossible to cover larger subjects.

If you make that choice is because you have skittish subjects that do not like proximity and are very small. Furthermore the Olympus 60mm has not stabilisation and therefore with our GH5 will only use in-body stabilisation. Another side effect of using this lens is that it is impossible to take shots of divers or anything else at medium range so the videos end up being a collection of very close shots that may please someone but result fairly boring.

Of course you can make this kind of video exciting to an extent like here

But at the end for me something like this is more fun although of course the quality is very different (I shot this years ago with a Panasonic LX7 and edited in iMovie)

The difference between the stunning video of Dustin and the basic video of mine is that you only have very close shots in the first one and frankly a slideshow of still images would be equally nice. There is no description of any sort of where is the fish what are the conditions or anything at all. You may argue that the stuff to see is not that nice but at the end this gives you a real idea of the diving where you go which is the purpose of my videos and majority of non Pro people. Furthermore medium size subjects that move like octopus, squids, crabs will almost always exhibit some kind of behaviour.

My macro video rig is built around the Panasonic 14-42 MKII which is the same lens I use for wide angle video with the Nauticam WWL-1. In effect am running video like a compact set up.

GH5 Macro Video Rig as at 29 March 2019

Ergonomics and lens

  1. The field of view with at 42mm is only 23 degrees horizontal and 13 degrees height this is ideal for portrait type of work
  2. I still use my old Sola 1200 video lights that can be used with a 20 degree beam creating a snoot like effect to better isolate your subject. It can be argued that color rendering index of newer lights is better but I think the narrow coverage of the lights is more important. Consider that at wide end the field of view is less than 60 degrees anyway with the flat port at 18mm
  3. I use two close-up lenses with a Saga dual flip diopter
  4. The rig as described is heavy in water more than 700 grams negative to ensure the required stability
  5. The tripod base has 2x 3″ segments and 1x 5″ segment to be as close as possible to the bottom this creates issue if you do not have a monitor as you need to have your face in the sand however once the shot is framed all is good

Close-up lenses

I use two close up lenses with this rig as the 14-42mm as a working distance in water around 26cm and a minimum frame size around 9cm that is pretty wide.

SubSee 5 wet lens

The SubSee 5 is in the sweet spot for the 14-42mm lens because it starts working pretty much when the 14-42mm can-t focus anymore and down to around 10-12 cm working distance. Minimum frame size is 46 mm

SubSee 5 + 14-42@42mm

Using the Ex-Tele feature in video means we can get to 33mm which is below the 36mm classic DSLR 1:1

When this is insufficient and the subjects are really tiny the next lens is the Nauticam CMC-2

Nauticam CMC-2 on Saga dual flip holder

The CMC-2 gives a frame size of 32mm as in this image

Panasonic 14-42@42mm with CMC-2

Using Ex-tele this becomes 23mm which is the same you get with the CMC-1 without ex-tele and is plenty for any purpose. It is theoretically possible to stack the two close up lenses but is not really necessary and the working distance too small. The CMC-2 works around 6-7 cm so you have still space for lights etc.

Olympus 60mm

Is there any use for this lens? Of course there is in case you want to capture a frame smaller than 23mm with the 60mm you can get down to 17mm with the bare lens to 12mm with the Ex tele, 9 mm with the CMC-1 and 6 mm with CMC-1 and ex tele. Will you be able to focus and work with the CMC-2 at 22mm from the subject is another discussion however for skittish subjects it gives you more working distance and this may be needed. I would recommend taking this lens with you for those cases but for video I do not see how you can really use the CMC-1. Please note the CMC-2 is useless with the 60mm as the working distance improvement is minimal to none.