What is the best ISO for video? How do you make sure your images are consistent and professional under different lighting conditions? Here’s your answer:
The following essay is written by Daumoun Khakpour
Low light situations and night time shoots in modern filmmaking is a tricky beast. While few filmmakers prefer to have their nocturnal or dimly lit shots grainy to help portray a realistic and minimal and grainy aesthetic, the vast majority would prefer if it was omitted entirely. The positive is, as digital camera technology improves throughout the year, low light abilities in cameras have grown exponentially. This allows for film digital to close the gap with film when it comes to low light and dark situations.
However, ISO settings are not universal, some cameras look better at different ISO settings, while some can push their ISO further, as grain becomes less noticeable in higher settings as opposed to other cameras. So, as a director or cameraperson, what is the best possible ISO setting for your camera?
The answer is simple: whatever the native or base ISO for your camera.
First and foremost, what is ISO?
ISO is the abbreviation of the International Organization of Standardization. It is a collective or group that standardizes products so individuals can compare and contrast various products and their results.
What does this have to do with the actual Camera and the image it can potentially produce? Well in regards to Photography the ISO follows a metric called ASA. Ultimately, this is a system or guideline that provides a cursory glance as to how capable the films sensor is at a given time.
With that said, not all ISOs follow a universal guideline or understanding as to what each setting should represent or their respective image quality. It however, provides a base standard of what to expect at each ISO setting and what happens if you adjust the setting based on the situation you are presented with. Higher end cameras tend to operate better in lower light situations, so you can set your ISO higher and have a lesser drop off in regards to Image quality and accurate colour. Within this, we must also realize that every ISO is made out of a sensor, and each sensor has a specific ISO setting that provides the Optimum result.
These native or Base ISOs are set by engineers and technicians who meticulously test and provide quality control for each camera model. They base these assessments and tests on colour science, the sensors, image quality and more.
Now that we have gotten that out of the way, the next question would be what is a base ISO? Simply put, it is the ISO in which you get the most dynamic range.
Now you may be asking what dynamic range is?
Dynamic range is the spectrum in which the most amount of detail can be caught on camera with in the lightest and darkest situations. The better or further dynamic range a camera has, the ability to capture detail in situations that would be too bright or too dark. This obviously would allow for a cleaner image that would vastly improve the production value of your film and/or project.
In simple terms the dynamic range provides the maximum opportunity for which the camera absorbs light. The less light, the harder time it has pulling information, colour accuracy or image quality. Again, each camera has its own dynamic range which has both a minimum and maximum setting.
However, going back to ISO, the higher you have to set your ISO the more “noise” or “grain” will be noticeable on the camera. This is again something that should generally be avoided as it can detract from the story or the images you as a filmmaker would like to put forward.
Simply put, at a specific ISO you will get your best signal to noise ratio, allowing for you to pull off the best potential images in low light situations.
Additionally, a camera sensor has both a limited and fixed ISO range. Unlike the human eye, which does not behave like a camera sensor. The human eye needs to adjust accordingly to low light situations, while the camera can adjust in a quicker fashion.
Furthermore, built into this, on top of additional grain that becomes increasingly prominent, you also lose colour fidelity and accuracy. This is a prevalent issue that is predominant in lower end cameras, again as digital technology improves, their capacity to mimic and rival film becomes closer and closer.
Building off this, newer higher end cameras have offered a new feature, “dual native” ISO. Which quite literally means that the camera has two ISO that are native to it. So you would have two settings which the ISOs would work best in depending on the circumstance.
Hypothetically, if you filmed two scenes in different ISOs, you should not be able to tell the difference with this feature. If you can tell the difference, it is just marketing jargon intended to sell the camera on a misnomer. The best example of a camera with dual native ISO would be the Panasonic Varicam. The Native ISO for these cameras would be a native ISO 800 and a native ISO of 5000. The 800 would be preferential for daylight, interior and studio scenes while 500 would work for night time scenes or any other low light situations. Panasonic also claims that the noise level at ISO 5000 would be near identical to the noise level at ISO 800, which is an incredibly bold claim. However, the key word here is near and not identical, so technically the camera only has one native ISO. Even cameras who market themselves as “ISO free” or “ISO-less” are again using marketing tools to sell their cameras. To reiterate it does not matter the make or model of the camera or what the manufacturer claims, there is a singular ISO that the camera looks best with in conjunction with color accuracy and dynamic range.
However, here is a where a problem presents itself. In regards to low budget filmmaking you cannot shoot at one ISO, as lighting challenges will continuously present itself. Although, there is a potential solution. Shoot a couple of scenes in low light scenarios with every different ISO setting, you can also do it with every half or third ISO setting, depending on how accurate you would like to be. While you are also doing this, you can test for under and over exposure, so you can see how colour and skin tones react to the different ISO settings. While this can seem tedious, or boring and bordering on the level of overkill, it allows for you to gain a level of comfortability with your camera and gives you a better understanding of the best situations to shoot with when it comes to settings. Also, while you are doing this test make sure not to change the aperture, white balance, lighting or any filters you may have on the lens. Changing shutter speed however, is fair game. Again, make sure you have a light which allows you to explore different between the different ISO settings.
To jump off this point, once you bring it into software like editing, you can use a production monitor to look at things like the different colour changes (blue, green, red etc…). Once you get the footage into editing, you can start grouping together the ISO setting depending on what looks best when paired with each other. So when you do finally film, you can see which group of ISO settings would look best for your camera once you do decide to film your project. This makes your life easier in post, when you are matching shots and do not have further headaches down the line in terms of consistency and continuity.
In summation having a deeper understanding of your gear and capabilities of your cameras ISO settings and sensor can provide you with a concrete understanding of how to achieve the best image possible. We are now in an era were increased dynamic range settings and are no longer available in higher end models as they become readily available in prosumer cameras. However, we must be ready to utilize the full capability of the tools at our disposable. By again having a concrete understanding of what ISO is, how our cameras operate best in low light and what our base ISO is we can seek to have the best image possible for our work. Additionally, by performing ISO grouping tests we can explore, the best 2 or 3 ISO settings for our cameras depending on the lighting situation. For low budget filmmakers, this is essential and can elevate production value and quality.