March 10, 2020
Michel Juknat

Advanced Exposure Techniques with MAVO LF

In this blog post I'm going to attempt to explain some of the more advanced features of Kinefinity cameras, which are not necessarily unique to Kinefinity but can be different from the way other manufacturers have implemented this technology.

What follows is the result of many months of testing and trial done in a large part by and with the help of Leigh Lisbão Underwood and Jeroen Van der Poel.


1. DUAL NATIVE ISO

Let's first talk about the Dual Native ISO of the MAVO LF since it is central to how all other elements function.

First, what is ISO? ISO stands for International Standards Organization, and it's simply a value which describes the sensitivity of your sensor. Each sensor has a "base" sensitivity, or in our case two (800 and 5120). The base sensitivity is the state where the sensor is not amplified, neither positively or negatively. To change the sensor's sensitivity the camera will add or remove an electronic signal called gain. In Kinefinity's "ISO mode" the gain is ANALOG, the image signal is amplified before the image is captured.

Kinefinity MAVO LF's two base ISO are 800 and 5120. This means that somewhere between the two bases there is a "border", a value which, depending on which side we are, the camera will choose the base ISO 800 or 5120 respectively.

At this point I'd like to make 2 important notes:  
1. the higher base ISO of 5120 has more noise than the lower base ISO of 800. This is normal.
2. In ISO mode, the border between the two base ISO will vary depending on a setting called "ISO Highlight Stops", which we will discuss in detail further down in this article.

Here is a video clip to show the difference on either side of the border:



2. KINEFINITY's HIGHLIGHT STOP SETTING

Kinefinity's "ISO Highlight Stops" setting (HLS) defines how many stops of dynamic range are available above middle gray (highlights), before details clip. Control over this setting is only available in ISO mode, and it ranges from 3.6 – 5.6 stops above middle gray, whatever is left is used for shadows. HLS can be set by the user and does not change even if ISO changes. Naturally, noise level & quality in the shadows are directly affected by the choice of ISO & HLS.

Here's a little animation of what happens with the dynamic range as you change the HLS value:

In this video we demonstrate how the HLS setting works in MAVO LF: 


3. EI MODE

EI stands for Exposure Index. While in terms of end result it indicates the same as ISO, the difference lies in how we achieve the change in sensor sensitivity. Other than ISO mode, in EI mode the camera will always record at one of the two Base ISO, though only while shooting RAW, regardless of the EI value you set. The difference in sensitiviy on the monitor is only apparent as it's achieved by adding or removing DIGITAL gain. Digital gain is not baked into your footage, as long as you're shooting RAW. A "transcript" of that digital gain will be recorded as metadata which can be used in post to achieve the same sensitivtiy as seen on set.

Note: In EI mode the border between both Base ISO is fixed at 2000-2560.

One other difference to the ISO mode is that in Kinefinity's EI mode the HLS settings change automatically according to the EI value. Here is a chart showing the HLS value for different EI modes, you can download this chart here:

In this video we show you more in depth what happens in Kinefinity's EI mode: 


Conclusion, ISO vs. EI:

Here is a chart of different ISO values in relationship to HLS value and the position of the "border between the base ISOs, you can download this chart here:



4. ETTL

ETTL comes from Expose To The Left and means exactly that. It's an alternative way to control Highlight & Shadow range (Dynamic Range distribution) – instead of using the HLS setting.
Here we purposefully choose to underexpose the image in order to have more range in the highlights. The effect is similar to raising the HLS value but with a major difference: In ETTL mode we set the camera to it's previously determined “Sweet Spot”, where we expect to have the best results in terms of lower or higher quality noise. We then use special LUTs (courtesy of Jeroen Van der Poel) to help with exposure during shooting, and to keep the same exposure in post.
As a result noise level & quality in the shadows change, depending on ETTL level.

In this video we explain more how the E.T.T.L. mode works: 

CONCLUSION:

There are many ways to get the most out of MAVO LF and any other camera for that matter. It's crucial to know the behaviour of the camera in each area in detail. Armed with that knowledge you then have different ways of achieving your goal. Which way is the best can only be found through testing...

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