Taking control over exposure

11/11/2013 20:00

For good looking footage, without brightness changes and choppy movement, the M (manual) mode is the first and only option. All the other modes (S, A) would allow the camera to adjust some parameter dynamically, which would result in inconsistent image.

The mighty M allows you to lock the following:

  • exposure time (affects the movement)
  • aperture (affects the depth of field)
  • ISO (affects the amount of grain)

Exposure time

This might be the most important parameter, as it has big impact on the overall feel of the footage. There is general rule saying that you should set this value according to formula:

exposure time = 1 / (Frame rate * 2)

That means, when shooting at 30 FPS, you should pick 1/60. It will make all the movement look smooth and natural.

This is also one of the reasons why the inability to shoot at 24/25 FPS doesn’t pose a big issue. If you would shoot at 25 FPS, you would pick 1 / 50 exposure. So for 1 second, the total exposure time is (1 / 50) * 25 = 0.5.

For 30 FPS, the result of the calculation is … exactly the same: 1 / 60 * 30 = 0.5 again. And because 25 vs 30 is not a huge difference, most people won’t notice you are shooting at slightly higher frame rate.

1/60 - car in the lower left corner is blurred by movement

1/1000 - car in the lower left corner looks still

Note: It is possible you won't be able to set 1/60 exposure time on your V1. It might get blocked by option Flicker reduction in the menu. In case you shoot outdoors, feel free to ignore it and set it to 60 Hz. In case you shoot indoor in PAL country with artificial lights, you need to respect the danger of interference, enable the Flicker reduction for 50 Hz and use the time of 1/100 instead. It is not much worse, and the light sources will not cause disturbing blinks in the resultant video.

There are few cases when you can ignore this rule and set even shorter exposure time - this is handy when you need to alter the feel of the movement for some reason. For example, in zombie movies, the undead are often shot (now I mean by camera) at short exposure time, to give them unnatural, utterly creepy and choppy movement.


Picking the right aperture for the shots depends on the two factors - what do you want to achieve visually, and … whether you have lens to do it. The more open aperture (= the smaller f number), the more narrow you get the depth of field, more light get’s collected and you can more easily separate the subject from the background.

The kit lens of the V1 are usually not helping very much - the 10mm starts at f2.8, the 10-30mm at f3.5. I can recommend getting the 18.5 f1.8 or/and getting the reduction for F mount lenses and buy some cheaper manual light glass.

The good news is that V1 sensor is a lot bigger than in most phones or consumer camcorders, which means you can achieve more shallow depth of field. On the other side, the chip is not as big as in DSLRs, especially the full frames.

The aperture choice can get you into problems when shooting outside. On sunny day, it is not possible to preserve open aperture, for example f1.8 along with exposure time of 1/60, even at lowest sensitivity (ISO). Everything would look burned out. You can consider purchasing neutral density filter, ideally ND8 and stronger. It is basically dark glass blocking a bit of light coming to the lens. This is better option than choosing shorter exposure time, because that would result in choppy movement.

Let's have a look at the following shot of the flower in front of building. The weather is bright, so when you want to maintain exposure time of 1/60, you need to go down to ISO 100 and you would still have to set aperture of f16 to avoid unacceptable brightness.

ISO 100, 1/60, f16

Just by mounting ND8 filter on the lens, it is possible to maintain the same exposure time and ISO, while the aperture can be opened at f1.8.

ISO 100, 1/60, f1.8

Note: The ND filters have the word neutral in name, but it is not true in all cases. Most of the ND filters alter the colors slightly, so choose your filter carefully!

ISO sensitivity

The choice of the ISO is quite simple - avoid the tempting AUTO option, which would lead to varying brightness, and pick one of the fixed values. Start with the lowest ISO 100 and go up when there is not enough light. The higher the ISO is, the higher the sensitivity to light, which also means more noise. The good news is that in real world scenarios you won’t notice the difference up to ISO 800.

Typical values (just to give idea, depends on the lens):

  • ISO 100 for outdoor shots on sunny day
  • ISO 200 for outdoor shots on partly cloudy day
  • ISO 400 for outdoor shots on cloudy day
  • ISO 800 for indoor shots
  • ISO 3200 for concerts in clubs and so on

The upper ISO bound is nothing to be afraid of too. Click on the following images to see full HD still from video, or watch it in motion at Vimeo:


"DVA", Brno 2013, lit only by projector
1/60, 50mm (135mm FF eq.) f1.8, ISO 3200

"MRC Riddims", Brno 2013, lit by lights + projector
1/60, 50mm (135mm FF eq.) f1.8, ISO 3200

"Napszyklat", Brno 2013, lit by single light source
1/60, 50mm (135mm FF eq.) f1.8, ISO 6400

Briefly on slow motion

The attractive 400 FPS and 1200 FPS modes V1 supports are an interesting bonus, allowing you to examine how things move, but they are not usable for serious video due to their minimalistic resolution.

To achieve footage 2 times slower, it is enough to shoot in 1280x720 at 60p. Please note in this case you will need to change the exposure time to 1 / (60 * 2) = 1 / 120, which requires better lighting conditions compared to 30 FPS video. You can usually compensate this just by stepping up one ISO value.

For super slow motion achieved via frame synth in post production, you don’t need to worry about original movement natural feel and simply pick the shortest possible exposure time (with respect to light conditions). This will eliminate the motion blur in the source footage, allowing more precise feature detection in post processing.


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