Tag Archives: Stabilization

SONY RX100, Stabilization, UNDERWATER VIDEO

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

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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, Stabilization, UNDERWATER VIDEO

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

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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.