Sunday, 14 August 2011

"Dances with fire", example Lumix 14mm video

This video was recorded using the Panasonic GH2 and the Lumix G 14mm f/2.5 pancake lens.



I left everything on auto, and just pushed the red video button. This gives me a 720p AVCHD video stream. Since I dislike the highest resolution 1080i mode, due to the interlace, I tend to use 720p progressive mode. I have the European version of the camera, so the frame rate is 50fps.

Sadly, the camera does not seem to record the image parameters when making video captures. So I don't know for sure what aperture, shutter speed and ISO was used. But I would guess the camera selected the largest aperture, f/2.5. And the shutter speed was probably as slow as possible for a 50 fps video, so around 1/60 second. The ISO was probably pushed up quite a lot, I would guess around 1600-3200.

Focus

I had autofocus selected (AFS). It would probably have been a good idea here to prefocus, and then select manual focus (MF) during the video capture. That is to avoid having the focus hunt during the video capture. You can see that the camera jogs the focus back and forth now and then, to verify that the image is in focus. But since the Lumix G 14mm lens focuses very fast, this is barely noticeable, even in this low light situation.

With the Lumix G 20mm f/1.7 pancake, the focus is slower, and it can wander off for some seconds when recording a video. For the 20mm lens, it is best to have some control over the focus during videos.

White Balance

The white balance was also left on auto (AWB). This gives a slightly yellow tint to the images. Perhaps I could have tweaked the white balance better. But this is hard to do when you don't have time to plan the video capture in advance. On the other hand, the yellow colours are actually true to the actual lightning conditions.

Flare

Notice that there is some flare in the video. You can see that the flames generate greenish ghosting symmetrically opposite along the optical axis. This is quite common when you have strong light sources inside the image frame.

This illustration shows the relationship between the actual light source and the flare:


A lens hood would not have helped, since the hood is only designed to keep out light which comes from outside the image frame.

Generally, flare is more of a problem the more lens elements the lens is composed out of. So generally, you would find flare to be a bigger problem for a zoom lens, which can easily have more than ten individual lens elements, than for a prime lens. The Lumix G 14mm f/2.5 pancake lens only has six lens elements. However, the optical formula and the quality of the lens elements is also important for the flare characteristics.

Using a protective lens filter on the front of the lens can give you more lens problems, especially for low quality lens filters.

Audio

I used the onboard microphone, and left the levels on auto. It sounds like the sound is clipped some times. But I would guess this is actually due to the sound system being run to loud, and not due to the microphone.

Using an external microphone probably has the potential to give better sound in the video recording. But it makes the setup look much more professional, which might scare some people, and hence negatively affect the video. Using the GH2 with the 14mm pancake lens gives a very compact and non-obtrusive package, which is handy for recording everyday life.

Lumix 14mm as a video lens.

The very fast autofocus and the inaudible focus action make the Lumix G 14mm f/2.5 an ideal video lens.

It has a generously wide field of view, which is useful when video recording a group of people. The wide field of view also makes it easy to handhold the camera without the hand shake affecting the video stream too much.

The small size and unobtrusive looks also makes it easy to get close to people without scaring them, which is a big plus if you intend to video record people.

On the other hand, a zoom also comes handy for video use. For some more flexibility, I would recommend the Lumix G 14-42mm f/3.5-5.6 basic kit zoom. It is light, very fast focusing, and pretty good quality.

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