Category Archives: UNDERWATER VIDEO

Underwater Video Tips: Using filters with your GoPro or Compact Camera

Filters Test

Following a number of posts about filters in various GoPro forums I decided to check in detail the behavior of the UR/PRO filters and see what is that they really do.

I guess the reason is that people do not really know or want to know the physics behind it and prefer to entertain many discussion that involve trial and error.

One of the most interesting one is this clip here that generated some ferocious comments by some users of other products that of course were not pleased having spent money that their choice seemed not to be the best.

To understand a bit more about what filters do we need to look at light temperature graphs like the one below.

techcolour-temp-chart

Light colour is measured in K and high value means cold blue light and low values represent warm red light.

As we know underwater red gets absorbed approximately at a rate of 1 f-stop every 2.5 meters we go deeper compared to blue light with the result that red colour disappears pretty quick followed by green to become completely blue at depth.

Some time ago cameras were shooting film not digital and there was no way to correct colours when the film itself got developed. So to perform some decent underwater photography people used strobes and fisheye lenses to get really near and blast the reef with light in order to restore the real colors.

This worked very well for close shots but was useless for wide angle at distance, so color correcting filters that could go underwater were developed for ambient light photography.

So what is a CC filter? A common misconception is that filters add colours to the picture, whilst this is practically true this is technically incorrect.

So what does a CC filter really do? As the word says it filters light, more specifically filters selected part of the color spectrum. This is done at expense of available light so if we use a filter we will have less total light or for our purposes exposure. This is well explained on the URPRO website where they talk about film sensitivity, if you use a filter you will loose 1 f-stop so use a higher ISO film.

http://www.urprofilters.com/content.do?region=FilterInstructions

The filter can be designed for different purposes and depending on its color and opacity will be more or less aggressive. If you read very carefully the urpro website says that there is a maximum distance that the filter will be effective at.

UNDERWATER FILTER DISTANCE

Photographically and visually reds, oranges and other warm colors become dominated by the natural blue-green (cyan) effects of the water when it is more than 8-10 feet deep.

Because all water is a continuous filter, the deeper a subsea photographer goes beneath the surface, the more colors are naturally “filtered out” of the spectrum.

As a result, the depth of the water must be added to the distance between the camera (or flash) and the subject to give the underwater filter distance. Use the following formula to determine the correct underwater filter distance:

+ Depth of water above the photographer
+ Distance from camera (or flash) to subject


= Underwater filter distance

Scuba divers using a still camera or a movie camera must combine the depth of the water plus the distance of the camera from the subject. This sum should not exceed 80 feet for color negative films and video, and should not exceed 30 feet for color slides. In all cases, the best color is achieved when the camera is close to the subject!

What that means is that the working distance of the distance is not the same as depth so you can push a filter say down to 24 meters but then the distance to subject needs to be zero. So if you are shooting something 3 meters or 10 feet away in 21 meters of 70 feet that as much as you can get.

When it comes to underwater use we are mostly interested in eliminating blue in tropical waters or green in cold algae waters.

In order to eliminate blue that has a high colour temperature we need warm colors typically something around orange. This will some of the blue beams and also part of the green beams and will produce filter light that is of a warmer color and will look ‘more red’.

But how much does for example a URPRO orange filter for blue water really warm up the light?

I have done some empirical tests with my Sony RX100 in a day where the Sony would measure a temperature of 6500K which pretty much correspond to cloudy day indoor.

Filter

The URPRO orange filter which is the same that is on the SRP filter for GOPRO measured 2800K with a tint of 5 Magenta. It also measured an overall absorption of 1 and 1/3 fstop of total light. I measure this filter instead of the one I have (which is not SRP and we can cover why in another place) because I think the SRP is the market lead at this time and it uses UR/PRO filters.

So the URPRO orange filter has approximately a 3700K warming effect with a strong magenta tint. This means that a camera with auto white balance and an average lens like a GoPro can restore some color in the image until the overall color of the light is around 10,000K in water. After that the filter essentially stops working and the light absorption is so much that it just becomes plain noise. I think this website gives a good idea

http://www.seos-project.eu/modules/oceancolour/oceancolour-c01-p07.html

So the reason why the picture stops having any red and starts looking green is that there is no red left in the light!

The breaking point seems to be around 18-21 meters or 60-70 feet and corresponds to our personal experiences I would say.

So what about custom white balance? We are pretty much in the same situation we can re-balance the camera up to 10,000K and add magenta or orange tint to the picture but you reach a point where there is too much red color noise.

The other advantage of custom white balance is that there is no light absorption so the picture ends up being less noisy as at the same aperture a loss of 1 and 1/3 fstop is like saying doubling the ISO from 800 to 1600 to capture the same scene. This is the reason a camera with custom white balance will always outperform the same camera with a filter at depth in terms of picture noise.

And what about Magenta filters? This is an interesting one as magenta filter absorb little light around 1/3 of fstops for URPRO and warm up the colour very little around 700-800K with a magenta tinge more prominent. A magenta filter will therefore absorb less light in total and introduce just a tint to the image.

From my tests a magenta filter is totally worthless on a camera that can white balance and frankly not that good at depth on camera with auto mode only. The reason is that light will get cold very soon at depth and the camera will be outside the AUTO white balance operating range (2700-7000  on average) pretty soon.

So what it means for users of GoPro cameras? The summary is pretty much like this:

  • In blue water filters are worth down to around 18 meters or 60 feet
  • In green water filters are worth even less as the color temperature very soon reaches a temperature where the auto white balance of the gopro is out of range

Although I have not yet measured I would think probably max 10 meters and that is it as I had similar results with my Sanyo that has same sensor size of the gopro and actually a faster lens.

Hope gopro users find this post useful as well as other users of compact camera to shoot video in ambient light.

In the next post I will compare the optical quality of the SRP dome port with the PolarPro snap on filter that generated such a debate on youtube and we will see why this filter could perform better than the SRP dome.

Sony RX100 – Summary of Underwater Video Performance

Few months ago this clip came out

Many people including me got really excited about this camera and had a go at underwater video with it

Now it is time for an end of year review and summary of my experience with the Sony RX100.

Without a doubt the camera is a game changer and there are some feature that are especially suited to underwater video.

Key Strengths

Bright Lens

The RX100 does very well in low light this is a strong selling point for underwater video, even in cloudy days the camera does extremely well

Low Noise

The camera performs very well in video mode up to ISO 800, the level of background noise is really low and the footage clearly benefits from it

Image Quality

The quality of video if we focus on the center, as well at the telephoto end is impressive. Color rendering is very accurate and there is even the option of using Adobe RGB. The dynamic range of the camera is excellent and the image is vibrant.

Video Mode Control

There is full manual control in Video mode and the option for aperture and shutter priority. The program mode does very well. Only an Auto ISO option in manual is missing but this is negligible. Indeed the most interesting mode is aperture priority.

Manual Focus

The peaking function works very well and it is really a strong feature of this camera, it is also very usable underwater

Battery Life

You can easily do 3 dives with the RX100 without having to open the case which is great and actually unusual these days when even a gopro does not last one hour.

Active Steadyshot

I initially slagged the RX100 stabilization system based on performance on land. However at a more in depth analysis it turns out that the RX100 active steadyshot, even if at cost of an image crop is very effective for sudden camera movement and for high magnification macro. The Stabilizer is not as sticky as others so when you eventually vibrate it does not jump. Although the performance for stills is poor to irrelevant and so is the normal mode the active mode is very effective for underwater use.

Tedious Workarounds

Some of the ergonomics of the RX100 are not the best and seriously deduct from an otherwise excellent experience, the most annoying issues:

Lack of focus lock

For some reason Sony decided to skip on this essential feature, the workaround involves switching to manual focus using the function dial however it is then possible to accidentally change focus.

Setting Custom White Balance in Video

Setting custom white balance is only possible in the still modes, while in fact if you shoot RAW don’t actually need white balancing. This is the largest non sense of this camera that requires the user to navigate out into Program to ensure white balance is set correctly and you don’t end up with the Custom WB Error message. Really an awful issue that Sony should try to fix in a firmware update

Lack of 24/25/30 progressive modes at 1080HD

Sony thought that for some reason you either shoot interlaced or you go directly at double frame rate with a 25 or 30 progressive mode only available at reduced bit rate and resolution of 1440×1080 with rectangular pixels. Why did they do that is a total mystery. You are therefore forced to shoot at the highest mode of 1080p50 or 1080p60 that produces large files difficult to digest by many programs. Sony decided to keep a bunch of interlaced modes despite the fact that there are no programs that can edit those without conversion and that CRT Tvs don’t exist since a little while.

AVCHD

Sony embraced AVCHD maybe because their software handles it well but what about the rest of the world? Mp4 is the standard for video clips on the internet and AVCHD adds absolutely no feature to it for simple video recording. Files have to be systematically converted, sometimes with commercial software, to be used with mainstream non linear editors, not only most would not recognize the files at double frame rate.

Key Weaknesses

The RX100 has also some key weaknesses that limit its own performance and can’t be cured by workarounds.

Macro Performance

The camera does an awful job at close range and needs a diopter even to shoot basic macro. To shoot super macro you need +12 diopters and this requires high quality lenses to avoid chromatic aberrations in the image. The focus mechanism with diopter is a bit of a mystery to work out at times. Once you manage to focus the image quality is great. However the need for a +5 diopter as a starter makes this set up expensive and cumbersome to handle in water compared to others.

Stabilizer

Sony has adopted a lens shift approach in this camera instead of the sensor shift of the higher end alpha, maybe due to large size of the sensor compared to the camera body. They have then added some software processing in camera but the results are just average. There are many other cameras that do better than the RX100.

Soft Corners at Wide End

I was going crazy looking at pictures taken with different wet wide-angle lens to check which lens was best, at the end of hours of observation I took some shots on lend at the wide end. The issue is not with the wet lenses is with the camera itself, it has very soft corners until at least f/5.6 and not the sharpest corners anyway afterwards. This cannot be cured and is a key weakness that is not so apparent in stills where you can crop quite a lot 20 megapixels but obvious in video.

No Neutral Density Filter

The RX100 has a bright lens and low noise however in video the ISO starts at 125, in many situation near the surface the camera maxes out at f/11 and then starts increasing shutter speeds to 200 400 800 and so on producing scatty mechanical images. Neutral density filters have been implemented for ages in cheaper camera and take away 2-3 f-stops allowing the camera to operate at wide aperture. For some reason Sony decided not to do anything about this. On land this is an even stronger limitation in bright days.

A final remark that I want to include for all those that use the RX100 for still photography that indeed is the real strength of this camera.

Another key weakness is the strobe recycle time not an issue in video of course but creating several issues of missed shots for photographer

In conclusion the RX100 can produce great footage but has some limitation that need to be taken into account.

If you go muck diving on flat surfaces with a couple of diopters and good video lights it is of course all looking wonderful but the situation changes when you cannot lay down as in my seahorses video

With two Inon UCL165AD stacked it is really hard to get some decent footage and due to the large sensor the depth of field at such level of magnification is pretty much zero.

But the limits show up more in the wide angle where the soft corners come up no matter what you do as very seldom you are able to shoot at f/5.6 or higher at depth below 12 meters or 40 feet

Whoever wants to try the RX100 for video please get in touch if you have more questions and happy 2013!!!

Sony RX100 – Tips for underwater video part 9 Wide Angle Shots and Lenses

During my last trip to Raja Ampat I had finally the opportunity to take the wide angle lenses in a real life situation and test that they were working to satisfaction. As some people know I really like my set of Inon AD lenses and although the RX100 has a 28mm equivalent lens I put together a bespoke adapter to reuse the lenses I already have. At the time of the trip I did not have the final prototype but only a pre-release which meant I could no use the fisheye as I had an alignment issue with the dome so I only used the flat UWL105AD.

There are two videos that are of interest one is the Raja Ampat North sites which is below.

In the north visibility was at best fair and I was struggling with the set up as I had not tested the push up filter. What happened is that the black ring created vignetting so I had to reverse the rubber ring on the lens until I could push the filter deeper. In the video you can see clearly a vignetting issue around 3:50 on the wobbegong approach where I had not yet resolved this problem. The video has no image stabilization nor cropping and it shows! There are also occasional soft corners as due to the low level of visibility and lack of light the camera was working around f1.8 or f2.0 aperture most of the time. This does create soft corners on the RX100 when you have something in close focus because I always shoot at the lowest ISO as I have found that increasing aperture and working with high ISO creates a mayhem of chromatic issues.

Anyway once I got a few dives and the problems were ironed out we also moved down to Misool where conditions where much better. This is the Misool video.

Here because of the increase of light and better conditions the image is sharper due to smaller aperture settings. I did not use the RX100 to take any stills as I wanted to focus entirely on video.

Once I got home I bought a fix M67-28AD adapter PRO, that allows you to adjust the AD lens so that the dome petals are in the right place. I tested it in the bathtub with the UFL165AD and the UWL105AD, in terms of vignetting as we shoot stills at 3:2 the working focal length is 34mm on the zoom or 12.8mm.

This is a shot of the bare lens

Bare Port

You can see the characteristic pincushion distortion that the bare port creates, this is the main reason together to demagnification to have a wet wide angle lens note the purple fringing is evident.

This is a shot at f5.6 with the UFL165AD.

UFL165AD 12.8mm

Despite the zoom the lens performs great and it is very wide. If we look at a 100% zoom of the corner

UFL165AD 100% crop

We can see that at this aperture the corners are sharp and there is a very small amount of red and blue fringing.

Let’s look at the Inon UWL105AD

UWL105AD 12.8mm

If we zoom into the corner this is what we get

UWL105AD 100% crop

Also here there is tiny blue and yellow fringing but the results are comparable to some shots I have been sent taken with the Inon UWLH-100 28LD.

Finally this is the UWL105AD with a 16:9 aspect ratio and 33mm equivalent zoom, this is interesting as it is the way the camera behaves in active steady shot without zoom.

UWL105AD 16-9 100 crop

As you can see even better performance in the corners as the port is closer to the back of the lens with the RX100 because of how zooming is implemented.

For who is interested I sell spacer rings and special screws that you can attach to the fix adapter at $45 get in touch if you have some old AD lenses and you want to reuse them with the RX100. Especially as the UFL165AD has incredible performance with stills and nothing can beat the flexibility of this lens and its very light weight in water let alone the speedy bayonet mount.

A final word about filters, in video filters are essential to restore colour however they also take away 1 1/2 f-stop of light so in low light the footage may get too grainy and it is actually better to work only with white balance.

I have heard many people commenting about the dreaded white balance error 9900K message of the RX100. So why is this happening?

It seems that the RX100 cannot white balance if the exposure is outside the -2 or +2 Ev range. If you do continue and ignore the error message you may end up with strange results.

So how to fix this? Contrary to what I said in my post about white balance I have worked out that it is best to set a custom white balance in P mode and not in M, this is because the camera will adjust exposure and never issue an error message. If you want to keep white balancing in M make sure you are within the allowed range of exposure.

Sony RX100 – Tips for Underwater Video Part 8 – Shooting at Night

If you are not freaked out by diving at night you know that it offers unique opportunities to see behavior and creatures not usually seen during the day like the monster snail in the featured image of this post.

During my recent trip in Raja Ampat we had the opportunity to see some really unique features, now for someone this fellow here is unusual enough

We had however made an indigestion of flamboyant cuttlefish in Dauin so that was not that exciting although having one of those walking towards the lens was pretty cool.

It is useful to compare the two still pictures of the flamboyant and the snail, you will notice that in featured image you can clearly understand the shot was taken at night whilst the flamboyant could have been just a day shot for how bright it is.

This leads us to tip number 1 for taking video at night which is never exceed with the lighting. We don’t have any ambient light to help and our lights are the only light source, it is very easy to exceed and wash out a scene with too much reflection from our subject.

I have lights that can be dimmed and I did not use more than half the power at night. It is also important to leave some form of dark halo around the frame to give really that night impression.

Coming to the light having bright lights on all the time also attracts lionfish, krill and plankton. On this trip I was literally attacked by krill to the point I had to switch off the lights for few minutes.

Back scatter is also more of a problem due to the particle in the water at night and the fact that they are more clearly reflecting our lights, if possible never illuminate a subject frontally to avoid the snow effect. Sometimes though, like in some sections of the video, there is just too much no matter how you angle the lights.

The real important part is the gear, I have video light that also change to spot and work as torches and are dimmable, this saves the effort of taking a torch with you and having to juggle with all the gear.

Other factor of relevance is that during a night dive you can’t really shoot wide angle as there is no ambient light, this limits the type of shots you can take so it is important to add something else to make the clip more interesting. It is also more difficult to film divers without blinding them so really there is less selection possible.

A final note are skittish critters that require a red filter, I have never been in this situation, usually I keep the lights low until time to take the shot and then go for it like for the eupalette shark towards the end of the clip. If you need to use a filter remember to set a custom white balance.

Talking of white balance every light has a specific temperature, mine are 6500K, it is a good idea to set the camera white balance to this temperature to neutralize the coldness of the light this is possible in video more on the RX100 but not all camera offer that option so you can start with auto mode to see how it works.

Anyway the video is the collection of the 7 night dives, some were not memorable but at least 4 were excellent you can see what I mean if you watch it in full and notice some of the specific quirks. I found the RX100 to perform very well and the footage is very clear. I used Movie mode P increasing or decreasing the power of the lights until I was getting the best compromise between aperture and too much light.

Sony RX100 – Tips for Underwater Video Part 7 – Macro Shots

Just came back from a 11 nights and 10 day diving on a liveaboard in Raja Ampat and I am in the process of putting together the summary videoclip for the trip. To have an idea of the kind of diving in this remote location you can have a look at the superb pictures that my buddy and fiance has taken on Raja Ampat 2012 Flickr Set

I had already gauged that the macro performance of the RX100 is far from outstanding and this trip just confirmed it.

To understand what I am talking about have a look at these two pictures both taken at 5 cm from the front port of the camera using a 3:2 format.

RX100Macro

The first image is shot with the RX100, note the shallow depth of field of the large sensor in P mode.

All looks good however if we take the same shot with a Canon S95 that has a 1/1.7″ sensor we get this result.

S95Macro

To make matters less complicated and don’t get too technical you can measure with a ruler the size of the memory card in the pictures. The S95 presents an image that is 26% longer than the RX100. It is like saying that compared to the RX100 the S95 has a 1.26x magnification.

In video diopters are not very popular because camcorders have small chips around 1/2.5″ and a 10x optical zoom and can focus at very short distance. So usually a no diopter is needed for regular macro work and a 4D is really only for pygmy seahorses.

With our RX100 however we need a 5D just to have a decent macro performance. Actually even a good size nudibranch looks small in the RX100 underwater without any lens. Moreover the RX100 has only a 3.6x zoom so even with a diopter that allows to focus a telephoto at closer distance things don’t really look that big so we are  looking at 5D for basic macro and 9D for super small critters.

The RX100 has a number of housing options with M67 thread as standard, this is the most popular format for diopters and there is ample choice there. If instead we want to use bayonet mounts we are pretty much limited to Inon or Seatool.

As discussed above we are  looking at a starting point of +5 diopter, this cuts immediately lenses like the Inon UCL330 out of the equation, if we look at the most popular and affordable lenses we are left with:

  1. Inon UCL165 6 diopters (1.5x) this lens is stackable
  2. Reefnet subsee 5 diopters (1.25x)
  3. Dyron +7 diopter (1.75x)
  4. FIT achromatic +8 (2x)
  5. Olympus +8 diopter (2x)
  6. Epoque DML-2 8.4 diopters (2.1x)
  7. Reefnet subsee 10 diopters (2.5x)

The first three options are adequate for most of the macro work with the RX100 and get you to fill the screen for almost all subjects except the smallest pygmy seahorses.

As we increase magnification we get the RX100 to a point where is very difficult to produce any decent footage. A 10+ diopter works very well for still pictures where you only have to take a single shot but for 10 seconds of decent footage is close to impossible to achieve focus without a tripod.

Looking at the featured image on this post this is a still picture with two Inon UCL165AD stacked at full telephoto. When I was in Raja Ampat I tried using two UCL165 it was very hard to get anything in focus however the performance is pretty good this is a snapshot taken from my footage.

Pygmy Snapshot

I posted all the pygmy footage on youtube

in this short clip I have a compilation of subjects, if you believed that an hippocampus bargibanti was tiny have a look at hippocampus denise, Pontohi and especially Satomi (1cm) in this clip to have an idea. All in all I am satisfied as I shot 12 minutes of seahorses and could use around 2 that were not too shaky. I do not use software stabilization as I don’t like the warping effect that CMOS sensor camera give so this is all done by hand. I did slow down some of the footage to half speed and this is were the 50 fps of the RX100 come really handy.

Other than Pygmy seahorses that are between 1.5 and 2.5 cm in size there is no need for such high magnification, in fact for the rest of the trip a single UCL165 has been more than adequate.

Looking at cost an Inon UCL165 costs less than a subsee 5  so that is the most cost effective option if you ever think you will need a very high magnification  and you are able to be super steady to avoid shake as it can be stacked with another UCL165 or an UCL330. Specifically having experienced the two UCL165 stacked I think that is probably too hard to handle so a combination UCl165+UCL330 should be the perfect choice for pygmy and similar at 9D alternatively a subsee 10seems the logical super macro choice.

A final tip is camera modes for macro, as discussed in a previous post aperture priority is the way to go and allows you to have enough depth of field so that you have sufficient part of the subject in focus. However this brings also the consideration about lighting. I took some shots in program mode with the RX100 and two Sola 1200, in some situations is quite hard to achieve f/8 or higher numbers with the two lights at the minimum power of 300 lumens with the lowest ISO. It follows that if you operate with a single light you need to have at least 800 lumens and put the light to the max, this may scare skittish critters and prevent you taking the footage you want. A possible solution is a red filter on the light followed by in camera white balance however a single light does produce harsh shadows and this needs to be taken into account.

In conclusion a diopter for macro work with the RX100 is a must so choose one that fits your needs and ensure you have sufficient lighting to support the small aperture required by the camera large sensor.

Sony RX100 – Tips for UW Video Part 6 – Housing Choices

I have a been a bit busy lately fighting with the MTS video files that the RX100 produces, I finally have an automated tool that converts all files into MP4 ready for iMovie that works a breeze.

Anyway this post is not about that workflow but about housing choices. I have received quite a few inquiries about housing choices and although I am not associated with any manufacturer or reseller I thought it would be a good idea to share my thinking.

When I had to choose a housing for the Canon S95 I chose a Recsea, in fact my buddy uses it, the latest WHC-S95D for still pictures and it looks pretty much like this.

A few bits got me frustrated with the Recsea housing one was the rear control.

This may look great but I have been frustrated when underwater the pressing of the buttons was mistaken for rotating the dial itself.

The other thing that I thought was pretty poor was the cold shoe for the focus light, this is a small piece of metal and the screws need to be treated with thread lock if you don’t want to lose it underwater.

Not to mention the mode dial that is really stiff.

Finally the bottom of the housing where the screws go is made of steel threads, in fact you should be careful not to leave an aluminum tray in salt water as it might corrode the housing. This may seem unlikely but I have seen other Recsea housing with huge speckles that mean corrosion.

Recsea produced a housing for the Canon S100 that introduced a front ring like the one on the camera itself but the housing remains the same of the S95 for the other features.

The choice of the Recsea housing over others at the time was mainly because it was easier and more cost-effective to get adapters for the Inon AD lenses I have.

So when the new  housing for the RX100 came out, first on the market from Recsea, I studied carefully the pictures to see how specific issues had been addressed. In essence the  housing for the RX100 is the same of the Canon S100 and has the same annoyances that I did not like with the S95.

So I waited until Nauticam came out with their product, which is in fact made by the same plant that did the Fisheye-fix for the S90/95/100 we can recognize the same features in this housing.

The first is that there is no integrated rear dial,  the buttons are separated from the rotation, this means the housing is very precise and there is never confusion in button presses and response from the camera.

The second is the top of the housing itself, the mode dial is smooth and the cold shoe is top quality as it was the fix s100.

The cold shoe is robust and takes easily not only adapters for 1/2″ loc-line but also 3/4″ which is great.

Finally as it was on the fix housing the bottom of the housing has got two zinc plates to act as cathodes and avoid corrosion.

There are other two incredible plus points of the Nauticam housing:

  • the moisture alarm, I don’t recall seeing one for a compact but the Nauticam has got it and it works as well
  • The housing has an M67 thread that allows you to mount lenses without adapters

Personally I don’t like M67 wide angle options for the RX100 as those are heavy lenses in water however if you already have them than you are sorted.

What about the Ikelite housing? Ikelite had issues of sticky buttons with the Canon S100 so for the Rx100 they have gone back to a large form factor. Personally I don’t believe a polycarbonate housing of such size is very appealing however if money is lacking this is the only choice at the bottom. It does not come anywhere near the quality and features of Nauticam or Recsea.

There is also another housing from Patima that has just been released, I have just seen the pictures and  it does not look particularly attractive, the closing latch looks ancient,  the rear section has button and dials too close and the control ring control placed on top of the camera is just unpractical. It is priced at source at $699 so 27% cheaper than the Nauticam, but this comes at a price: there are plenty of design shortcuts that may create usage issues underwater.

In conclusion the Nauticam I believe offers the best quality and value for money for the RX100, with the exception of the front ring being operated in a traditional mode I don’t see any faults with this set up and I would recommend it for both video and stills, if you don’t have that amount of money and you want to use your RX100 just for video then the Ikelite is worth a try, but not if you want to use the camera also for stills. Nothing specific to Ikelite but transparent housing give too many issues with strobes to even bother.

Sony RX100 – Tips for UW Video Part 5 – Video Modes

Yesterday I had the opportunity to take the rig in the pool and try the steadyshot in water. Clearly it is not really accurate to compare like I have done but it gives an idea you can check it out

This made me think about the video modes implemented in the RX100, as we know there are 4 surprisingly for a compact:

  1. Program
  2. Aperture Priority
  3. Shutter Speed Priority
  4. Manual

The manual option may sound very exciting to someone that comes from still photography but in the end is not that significant in video. Not sure how many have heard about the ‘180 degrees shutter rule’ anyway google it there is some good explanation there. In essence once you fix the frame rate you have pretty much fixed the shutter speed as well so this takes away one of the exposure variables, we are left with aperture and ISO.

Aperture is available in 1/3 of Ev however in wide angle shots with a wet lens most of the times with subjects 10 feet or 3 meters away the camera even with this size sensor has so much depth of field that there is no much point bothering.

ISO in video goes from 125 to the max in 1 f-stop increments so after 200 you have 400, 800 and higher values that are not good for video as the H264 compression makes the footage grainy. I would recommend limiting the max auto iso to 800 or maybe 1600.

So the manual mode allows you to set the exposure, now is that a good thing? As seen earlier on Part 2 this is indeed a good thing in specific situations such as wreck penetration, caves and the likes. It is not however that great for general wide angle and if you ever happen to do camera pan or change the angle of the camera. Panning is not that great in underwater video but sometimes you need it and fixing the exposure is not a good idea.

So the Manual mode is good to take control of the camera in specific situation but in most cases is an overkill as there are not many parameters you can really change independently.

Following on from the shutter speed 180 rule the shutter priority is also pretty useless as we should set the shutter value to a multiple of the frame rate to avoid stuttering.

Aperture priority is instead a great value add of the RX100. Diligently the camera will try and respect the 180 degree shutter rule but in specific cases, for example when doing macro with diopters or in close up, we want to really make sure we have the depth of field required. In that scenario I recommend leaving the ISO on Auto and not set it manually.

So why Auto ISO? Because changing ISO in a digital camera is done amplifying the signal, is not changing film, so in effect the ISO does not need to go in f-stop values at all. So leaving it on ISO the camera might as well apply values that you cannot choose manual.
This uneventful picture taken with the RX100 and an Inon UWL105AD shows a value of 320 in ISO as it has been shot in program mode.

We could not select this value if we were setting the ISO manually but would have needed to choose between 200 or 400.

Aperture priority is my favorite mode for those special situation where extra control is needed.

So what about the Program Mode? Actually that is not bad at all, especially for wide angle shots, as mentioned the shutter speed is pretty much set, in program the camera tries to keep the lowest ISO as possible and opens the aperture accordingly. This behavior may be acceptable with sufficient ambient light so I would not discount this mode at all.

Not bad for program mode with no lights…

A final note the camera uses a shutter speed of double the frame rate in Active Steadyshot and the same as frame rate in standard mode, also for this reason I do not recommend the standard steadyshot even if Active crops the picture in the 1080p50 mode

Sony RX100 – Tips for UW Video Part 4 – SteadyShot Modes

In this post we will look more closely to the image stabilizer options built into our RX100.

The RX100 is equipped with the Sony Steadyshot technology that has been around for quite a while however in this new camera we have a new additional feature that may as well worth exploring for our purposes, the Steadyshot active mode that was first introduced in the alpha series.

The active mode is only available for movies; for stills the choice is limited to the Standard mode, it is of course possible to switch off any type of stabilization, I do not recommend doing this for movies.

So how does the Steadyshot system work?

The standard mode is based on a gyroscope sensor present inside the camera that gives information to the microprocessor so that this can adjusts the relative position of the camera sensor with respect to the lens and compensate for the movement of the camera. More details are on the Sony website here.

There is no doubt that optical stabilization is a great help for still pictures however we have all experienced that this does not really lend a great help in situations where the camera moves quite a bit, for example if you walk with it taking footage, or in a dive when you have surge or uneasy conditions.

Usually in post processing we then add a software stabilizer that works out the camera’s pan and rebuilds the frame around it, this  comes at the expense of cropping.

Some cameras do not have an optical stabilizer but only an electronic system which is equivalent to the routines that editing program implement in post processing, Sony with the SteadyShot Active mode combines optical and software stabilization techniques.

I have put the RX1oo on an tripod fronting the window frame and set the camera in SteadyShot Standard mode, the diagonal field of view in this case is 73.44 degrees (it is actually 72.97 if we calculate accurately but let’s not worry for now).

You may wonder why this is not in excess of 75 degrees as the camera has a 28mm focal length at 35mm equivalent, this is because the camera sensor is 1″ wide with a 3:2 form factor, but in movie mode we are in 16:9 so part of the picture is lost and this makes the field of view smaller. In fact Sony declares the 35mm equivalent as 29mm in Movie mode, against a more accurate calculation of 29.25mm.

In this shot we see the camera in the same position but now in SteadyShot Active mode.

We see that we don’t have anymore any light on the sides of the window frame in fact right now this completely fills the camera frame.

Sony declares an equivalent 35mm focal length of 33mm in active mode that reduces the diagonal field of view to 66.5 degrees this corresponds approximately to a 10% reduction at field of view level. This crop is needed by the camera software in order to work out the camera pans and have sufficient margin of error for the calculations.

Now when it comes to underwater video should we be tempted by the SteadyShot active mode even if that means loosing some field of view? I guess it depends, most of compact camera users do not have underwater tripods, and the additional stabilization help is welcome especially when zooming in for example for macro or performing panning shots.

In this video you can compare the two steadyshot modes

This also brings another consideration in mind, there are many wide angle lenses designed for cameras with 35mm equivalent focal lengths, that could be suitable if we intend to keep the Steadyshot in Active mode.

A lens that immediately springs to mind is the Inon UWL-100, this is a lens with an M67 thread as natively supported by three of the housings currently available for the RX100, the Ikelite, the Nauticam and the Patima, an M67 mount adapter is also available for the Recsea housing.

The Inon UWL100 supports camera with focal lenght >31.5mm and would on paper be suited for video use with the RX100 with steady shot in active mode, this lens should not vignette at the widest setting due to the image crop and reduced field of view of the 16:9 frame in movie mode.

Another lens that come to mind similar to the Inon is the Epoque DCL-20 or Ikelite W20 those correspond to the Inon UWL-100 with mount type 2 and might not be suitable for the Ikelite housing. Ikelite tends to position the thread further away from the port so I invite you to test yourself before drawing conclusions as the increased distance lens to port generates soft corners.

Finally the Olympus PTWC-01 is also a potential candidate for testing for what concerns the M67 options.

If you happen to have any of those lenses with your current set up and are thinking of upgrading to the RX100 to use it for video you may well be able to use your lenses again and save yourself additional investment.

Sony RX100 – Tips for UW Video Part 3 Setting Custom White Balance

In this third post we will look at setting custom white balance in our RX100.

The ability to change the color temperature and adjust it to the conditions is essential to take underwater video as the ability to correct white balance in post processing is nowhere near what you can achieve with RAW files in photography.

Unfortunately the RX100 does not allow to set a custom white balance in video mode, and actually does not allow setting it in many other modes either. So to achieve our objective we will need to use the mode dial.

Note that the RX100 has the ability to store custom setting in 3 memory recall modes however in this mode the set custom white balance option is not available.

As we don’t have a one push option we need to minimize key presses to build a reliable routine that we can recall underwater.

If we have a look at the mode dial we see that the Manual mode for stills M is the closest to the video position so our routine will be based on switching between M and Movie mode. Update The new recommendation is to set the dial to P see note at bottom

Preparation is important and the RX100 has two options when it comes to recalling functions from the menu as we can see from this picture.

It is essential for our purposes that in this screen we select Previous, this will position us on the last entry we used when we click on the menu button again. The other option Top does not recall what the last entry was and puts you back on the top of the relevant menu, and would mean more navigation for us, so make sure you are set on Previous.

Another important trick to remember is that through the Function button we can recall the various white balance settings. In my set up white balance is right in the center of the function option so that when the function button is pressed we are immediately there should we need to change it back to Auto when we use lights, so when we plan to custom white balance this should be left on the Custom position as in the main picture of this post.

The other preparation that we need to do is to go in Manual Program mode and navigate until we reach the entry that allows us to set custom white balance as shown in the picture.

Note that from here we still have to actually select and go into another menu to then finally navigate to the bottom where the set custom wb option is.

We now want to re-balance either on slate or some grey area or sand so how do we do it?

The starting point will be in Movie mode with the White Balance set to Custom (remember this is not to set a new WB but just to recall the last white point set).

This is the step by step routine:

  1. Move the dial to position P
  2. Press Menu – this will position us on the white balance entry in the menu
  3. Press Enter (central button) to access the options
  4. Scroll to Set Custom
  5. Press Enter
  6. Point at the slate and press the shutter
  7. Press Enter
  8. Turn mode dial to Movie – as we were set in function to Custom White point recall the setting we capture will be used

And we are done an 8 steps routine!

If you were used to a one push option this is a shocker!!!

For those on the more conventional option Menu-White Balance-Custom WB-Set-Menu this adds 3 more clicks.
Sony had made two very poor design decision for our underwater video purposes

  1. It has negated the option set custom white balance in video and now two turns of the Mode dial are necessary
  2. It has allowed to set a custom white balance only from the Menu but not from the White balance options that you can recall with the Function button, additional navigation is required because of this

I believe those issues can be fixed by a firmware update quite easily as they are clearly software issues the camera itself has got all the required capability.

That’s all for now if anybody has any alternative approaches that improve this routine I look forward to hearing what those are!

Meanwhile I recommend sending an email to Sony Support to ask for firmware changes…

Update 14 December 2012

Many people report a Custom WB error 9900K message. It turns out the RX100 fails to set custom white balance set up if the exposure is not within -2 to +2 range. So the new advice is to set custom white balance while in P mode

Sony RX100 – Tips for UW Video Part 2 – Rear Dial Buttons

In this second post we will look at how to set the rear dial buttons to best suit underwater video.

The RX100 has got a whole load of settings and not the most user friendly menu structure so it is important to have the features you need at your fingertips when the moment comes.

There are 3 essential features that a camera needs to have for underwater video:

  1. AF lock
  2. Exposure Lock
  3. Set custom white balance

Unfortunately as Backscatter noted in their review of the RX100 there is no possibility to set a custom white balance in any of the video modes, however in the next post I will guide you through the best available workaround that minimizes the chances of you getting completely lost in the menus…

It may be beneficial to understand first why those features are important so let’s have a look one by one.

AF Lock

Have you ever experienced being in a school of fish? Or looking at some frantic behavior in front of you or simply seeing glassfish swarming in front of your camera lens?

It will look something like this…

This is not a still picture but a snapshot of a clip taken at 1/125 sec shutter speed, the action was actually fairly fast.

This is the clip if you want to check it out,

this scene is in the first part of the movie and  has been shot with AF Lock on a Sanyo Xacti HD2000.

What would have happened without AF Lock? The camera would have been looking for focus and mistaking some of the fish coming close with the actual subject and as result the clip would have been unwatchable. So this makes focus lock very important for us in all situation where we operate in tripod mode with moving fish in front of the lens.

The RX100 does not offer AF Lock with a single push, and in video mode the choice is between tracking auto focus and manual focus. To emulate the AF Lock feature I follow this procedure:

  1. Track my focus point with tracking AF
  2. Switch to Manual Focus

Note that is not possible to simply cancel tracking AF to obtain AF lock as the contrast detection system will still wonder around the center of the frame.

This means that one of the rear dial buttons accessible in the menu settings 2 should be set to AF/MF Control Toggle that will allow us to quickly operate the steps above and move with one click from tracking AF into manual and effective locked focus.

Exposure Compensation

Another essential feature of video as we don’t want the camera to continuously adapt to the changing light conditions of the scene. To give an example let’s have a look at this picture:

This is a swim-through that is a common features of little caves or even wrecks. We don’t want the camera to compensate for the lack of light whilst we go through as that would increase the ISO and make the footage grainy, also the scene would get brighter and not reflect to the viewer the same experience we had.

Exposure lock avoids this situation so when we are at the beginning of the cave we lock exposure and the scene stays dark so that the end of the swim through gives a beautiful effect. Another example with this technique

So we should reserve another of the rear dial buttons to Exposure lock that on the menu system is called AEL Toggle

This is how my rear dial configuration looks in the Setting menu 2

Note that I left the center button to standard as that corresponds to tracking focus. That is required for the pseudo AF lock in conjunction with the Right button as discussed earlier in this post.