Sunday, 26 August 2012

2x Fisheye on a bicycle

It so happens that I have both the fisheye lenses available for Micro Four Thirds at this time. I bought the original Lumix G 8mm f/3.5 fisheye when it was available. It is a fine lens, for sure, with good sharpness even in the corners.

The Samyang 7.5mm f/3.5 fisheye lens did interest me, and I decided to pick that one up as well. It is much cheaper, and performs even better optically, in my experience. The Lumix lens can be better when photographing close items, like closer than around 30cm (one foot). Then, autofocus is useful. Otherwise, I generally use the Samyang lens now.


But having both at the same time can also be useful. Since I have both the GH1 and GH2 cameras, I can use both lenses at the same time. Mounting them both to my bicycle using Manfrotto Superclamps and ballheads, I can record the scenery passing by from two angles, which can make some interesting footage:


Here is the footage I ended up with, after editing the video. I'll get back to the details of how I edited it later in this article:



Front camera

Pointing forwards, I have the GH1 camera with the Lumix G 8mm f/3.5 fisheye lens. The camera is set to auto-ISO. With the exposure set to f/3.5, 1/25s, the camera has picked the maximum ISO 1600 for most of the ride, which is still a bit too low, leaving the footage a bit underexposed. I pre-focused at about 1m distance, and left the autofocus off. The camera records at 25fps 1080p.

Rear camera

Pointing backwards, I have the GH2 camera with the Samyang 7.5mm f/3.5 fisheye lens lens. I used the same settings as for the GH1 camera above. However, the auto-ISO goes to 3200 for videos, and hence, the rear camera has a better chance at capturing a more correct exposure.

In my experience, both cameras will consistently underexpose when using the Samyang lens at night, with high contrast. So I dialed in +1 1/3 exposure compensation.

Video editing

First of all, I had to synchronize both video streams, which was quite difficult. In retrospect, I should have clapped my hands in front of both cameras, to have a more clear point of reference.

Here you can see both videos in the Kdenlive video editing software timeline. The GH1 footage is on the top. I'm using the audio from the GH2, pointing backwards.


Then, I wanted to fit both videos into one single frame. This was achieved by cutting off the top and bottom of the original frames, and then compressing the rest by about 20%. To do this, I use the "Scale and Tilt" effect in Kdenlive, with these parameters:


Here is an illustration of an example image frame before and after cropping and scaling:


After halving the vertical size of each stream, I can fit both of them into one 1920x1080 video frame.

Conclusion

One would think that having two lenses that are virtually equal is a waste of money, but it can give you some creative possibility.

After seeing the resulting video, I think I should have cut it much shorter. I doubt that many will want to see the whole thing, as it is too long.

2 comments:

  1. Good fun. Obviously a different front camera mount location for the next run. Probably still on the frame, but further forward.

    Thanks for sharing.

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  2. I think it is a bit fun that the handlebar is visible in the top frame. But I agree with you that it takes up too much of the visible frame. So you are right that a different position would be preferable.

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