Chris,
Interesting take on this. Not quite hat I was expecting. Need to think about it.
Anyone have insightful comments on this? A couple of observations ... regardless
of how big the image of the "target" is it is given that the subject is 1 inch
or 25.4 mm so size on screen does not matter.
I don't quite understand: "In the second photograph the subject is a vertical
black object and the background is lit". - Hmmm are "we" thinking in negative or
positive terms? Interesting. A possibly ponderable alternative. Hmmmm ... but it
seems the original premise was turned around as it is given that the background
was NOT lit - it was a very black background. So some thought has to go into this.
have fun!
andy
Chris wrote:
In the second photograph the subject is a vertical black object and the
background is lit. The object is oscillating from side to side and completed
one cycle during the exposure.
The sides of the second print are black because the object is stationary
briefly there and the gradation is due to its acceleration in Simple
Harmonic Motion as the object spends less time obscuring the light as it
speeds up.
In the middle the object is travelling at its maximum speed and at a density
of 1.25 (given above) the exposure time is 1/20 second. The object travels
about 1 cm on my screen print size and so is doing 1 cm in 1/20 second so
about 20 cm/sec.
Chris
-----Original Message-----
From: owner-photoforum@xxxxxxxxxxxxxxxxxx
[mailto:owner-photoforum@xxxxxxxxxxxxxxxxxx] On Behalf Of ADavidhazy
Sent: 17 November 2009 22:04
To: List for Photo/Imaging Educators - Professionals - Students
Subject: Sample question FYI
My students will be taking final exams tomorrow. You can review and ponder
about one of the questions (for entertainment value!) at the following URL:
http://people.rit.edu/andpph/a-pix/2009-sensi-1.jpg
click!
andy
