Practical advices about ND filters PART III

Staff Blog

Practical advices about ND filters PART III

Oct 17, 2016

• Typical situations
• Time-lapse
• Strong light flux
• Smooth dynamics
• Blurred motion
• Shooting of the Sun

Time-lapse
Practical advices about ND filters PART III ND filters are often used in time-lapse, so lets consider the typical situations.

Strong light flux

 In fact, the situation is quite similar to classic photography. Time-lapse is a video made of a large number of serial shots. But there is an additional restriction - to avoid flicker effect you always have to shoot with a maximum aperture, if your lens has automatic aperture control. The fact is that during the serial shooting after each shot the camera sets the aperture into the initial (most opened) position and then closing it to the set value before the next shot. This action is repeating before the each shot. Here is the sample video of serial shooting on F2.8 lens with f/5.6 set:

And the point is that the automatic setting cannot close aperture into the identically same position. Every time the f-number will be a little bit different. That means that with every new shot the camera sensor will receive different value of light, so the final images will always be exposured in a different way, that is well seen in dynamics:

Therefore, in order to have a constant light flux when shooting time-lapse, it is recommended to set the aperture into the most opened position. That means that you would either have to shoot with very short shutter speed (which is undesirable and this will be considered below), or get an overexposure with a longer shutter speed.

That is, if in the classic photography setting the open aperture can be caused only by the situation (portrait photography), in time-lapse you always have to shoot with maximum aperture (unless you have a lens with manual aperture control).

Smooth dynamics

As we just mentioned, strong light flux and importance of shooting with wide open aperture gives us no choice, but to shoot with a fast shutter speed. However, in this case the final video will turn jerky and unpleasant for viewing. Using ND filters allows us to lower shutter speed and make video smoother.

Blurred motion

Blurred motion in time-lapse looks as good as in classic photography. But unlike the photos, the footage will look interesting both night and day, because it allows to express the dynamics. This technique is perfect for shooting of moving cars or flows of people. But if you shoot with a faster shutter speed, the final video, again, will look jerky.

Shooting of the Sun

Time-Lapse video of the Sun looks interesting too, especially during sunset and sunrise.

To be continued....