Understanding Dual Native ISO and Dynamic Range on the BMPCC6K Pro

We’ve covered Dual Native ISO for the Blackmagic Pocket 4k, but with the release of the BMPCC6K Pro, I thought it was time to update that video and expand on another year of experience. I’ll also walk through the different settings and discuss why dynamic range is important for your finished product.

What are ISO and Native ISO?

First we need to address ISO. Because there are plenty of resources across the web that go in-depth on what ISO is, I’ll be quick.

ISO is simply the sensitivity of your camera to light and was as a rating in film for light sensitivity of film. In modern cameras ISO refers to the camera sensors’ sensitivity to light and how users can increase or decrease to add or reduce light. By digitally amplifying the ISO levels, you can run into issues like noise, image quality, or color shift in your images.

Now, while each camera has different tolerances, all cameras have a sweet spot in their ISO that is known as Native ISO. Native ISO is the baseline setting your camera is set at to achieve the most detail out of your image. Going above or below this setting will digitally un-amplify or amplify the sensor’s sensitivity to the light it is capturing.

Native ISO is the level you are generally advised to stay at when filming. Additionally, you will get the best results without any of the effects that over-amplifying or amplifying can cause. 

How the BMPCC6K Uses Dual Native ISO

Next we have to look at the Blackmagic Pocket Cinema Cameras offer a Dual Native ISO system. This feature gives users a camera with two systems of ISO that offer more flexibility over lighting situations. The first system ranges from 100-1000 ISO with a native of 400. The second system ranges from 1250 ISO to 25,600 ISO with a native ISO of 3200.

When you adjust your settings in-camera, it will automatically switch over to the secondary ISO system when you surpass 1000 ISO. This means that if you are shooting in a poorly lit situation, you can kick into that higher ISO and still get a clean image at the brighter 3200 ISO. Blackmagic is optimized this way to minimize grain or noise in the footage while maintaining the full dynamic range of the sensor. 

How Dynamic Range Factors In

When we start talking about dynamic range and the BMPCC6K Pro, we have to start thinking differently than with a DSLR or mirrorless camera. These equivalents rarely have dual ISO systems.

But first, a quick refresher on dynamic range.

Dynamic range is the camera’s ability to capture stops of light above and below middle grey. The more dynamic range you have, the better your camera is able to capture the highlights and shadows in an image.

The BMPCC6K Pro has 13 stops of dynamic range. It peaks at about 13.4 stops at 400 ISO and at 12.1 stops in the secondary 3200 native ISO.

When you adjust your ISO levels, the dynamic range values shift where they are For example, at your native ISO of 400 you have 5.9 stops above middle grey and 7.5 stops below. For this ISO, you have slightly more dynamic range in the shadows, or darker, areas of your footage.

Now if you went all the way back to 100 ISO, you only have 3.9 stops above middle grey but 9.5 below. Oddly enough, this gives you very little range in the highlights of your image. You would actually have better success filming at 1000 ISO in direct sunlight because it has 7.3 stops above middle grey. This means that, if properly exposed, you will get more detail in the highlights than at 100.

How Native ISO Affects Your Footage

As you learn the BMPCC6K Pro, your understanding of how the dynamic range is shifted when the ISO changes is crucial for quality footage. Shooting at the wrong ISO levels, even with the ability to change in post-production, will not get the footage to the appropriate setting.

This is why I always recommend filming at the native ISO levels. Here you get a more balanced dynamic range and it’s the ISO setting that should give you the best image quality. I’ve had a lot of people express to me that they find that 400 ISO has more noise on it than at 100 ISO. However, with RAW footage you will typically see more noise on it than a non-RAW codec. But – more noise isn’t necessarily a bad thing.

3 Reasons to Film in Native ISO

Here’s why I always recommend filming at native ISO:

Wiggle Room

Running at 400 ISO gives me some wiggle room when editing – especially if I got my exposure wrong. I have plenty of room to adjust if I underexposed or overexposed an image. It’s nice to have some redemption if something doesn’t come together perfectly. 

Balanced Dynamic Range

Native ISO has a fairly balanced dynamic range – making it perfect for normal lighting situations. With 5.9 dynamic range above and 7.5 below, you get a decent amount on both sides of middle grey. I would only recommend going to other ISO levels when extreme lighting conditions call for it. 

Touch your ISO levels last

The last thing you should be adjusting is your ISO levels. You will want to utilize your aperture and ND filters first and only start dipping into ISO when necessary. Remember to reference where the dynamic range levels lie in the ISO you are changing to if you start adjusting.

The absolute last thing you should do in a brightly-lit environment is adjust to 100 ISO. This means there is so little dynamic range in the highlights. Similarly, you may want to consider switching to the secondary ISO in darker situations. Even at 3200 ISO, you get more dynamic range below middle grey than at 1000 ISO. It also produces a lot less noise. 

Is Native ISO Right for You?

Now, as I say with all my videos and in all of the Frame Voyager content, you control your experience. Experiment with the different ISO levels and get first-hand experience of how they perform at each level. Understanding the theory and technical reasons important – but so is seeing it with your own eyes in your own environment.

This is a critical part of the BMPCC6K Pro to understand and could save you from filming for a client or project and returning with unusable footage.

Please feel free to comment below with any questions or thoughts, and I’ll respond as soon as I can.

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