Monthly Archives: September 2012

Practice Derby #7

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I went to the York River again for the last practice derby entry before the NCC. Since I damaged one of my amas and I feared I could not do an adequate repair before the big race, I borrowed some amas from the dealer (Peter) in Florida. These amas were previously damages and repaired and I like the repair job. As the video shows, a large piece of twill weave fabric (wither fiberglass or carbon) was placed as a cap over the whole wing connection area (and farther) to really distribute the forces from the ama. I plan on doing something like this to repair my own amas after the NCC race.

The day testing them out was a fairly light wind day but they at least remained water-tight.

Practice Derby #6 (Harlowe Canal reconnaissance)

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The plan was to start at Oriental, go through the Harlowe canal, then on to Shakelford banks, camp out, then return to Oriental by way of the intercostal. We had to cut the trip short (turning around at the airport near Beaufort) because I developed a structural crack in my port ama which made more adventurous sailing dangerous. We patched it (thanks to DogsLife) with some plumber’s glue, added some extra lashing to hold the ama on, and limped back to Oriental through the Intercostal. All in all, we did manage most of the trip.

The video below shows the Harlowe Canal part of our trip.

I’ll post another video later on that shows what is going on with my amas and the loaner amas that are being shipped to me.

Perspective

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There were some recent forum comments suggesting that some videos of sea conditions did not accurately capture what the captain felt the see conditions were at the time. I kind-of jokingly quipped that this may be because a wide-angle lens makes close-up things seem bigger as compared to far away things. It was then quipped that if a wide angle lens made close things abnormally bigger and far away things abnormally smaller then a telephoto lens would make far way things abnormally bigger and close-up things abnormally smaller – implying that if close-up things were not in fact abnormally smaller with a telephoto lens, then the statement about wide-angle lens would not be true.

Well it is obvious that a telephoto lens will magnify both close up and far way things but does this fact necessarily negate the statement that a wide-angle lens will make far away things seem smaller relative to close-by things as compared to other focal lengths?

To test this, I did a quick experiment. I set up two 1-foot rulers separated by 6 feet and placed a camera one foot away from the closer ruler.

C       R1                                                   R2

One foot between the camera and the closer ruler and 7 feet between the camera and the farther way ruler. I then took three pictures. Two with a Canon PowerShot Elph 300 HS camera – one in wide angle and one in telephoto mode. Then I took another picture with my GoPro camera in wide angle mode. After cropping the pictures, I compared the vertical distance of the far-away ruler (in counting vertical pixels in the image) to the close ruler. I counted 16ths of an inch on the closer ruler.

If the comparisons would have been all the same, then that would mean that there would be no contribution to the focal length in preferentially magnifying close-by things relative to far-away things.

The pictures below show what I got.  The numbers/16 are the length of the far-way ruler superimposed on the close-by ruler measured in 16ths of an inch.

The faraway ruler appeared bigger with the telephoto image relative to close-by ruler when compared to the two wide-angle pictures. It wasn’t a dramatic difference, but a difference never-the-less. So, to a small degree, a wide angle lens will preferentially make far-ways things seem smaller relative to closer-by things.

Undoubtedly, there is a large psychological aspect with all senses in play and attention acuity focused on the sea conditions for a captain in the moment that probably explains most of the feeling that the videos didn’t do it justice. But there is a small contribution to this feeling due to the wide-angle lens.