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Re: projectors



Speaking of resolution, I just returned from doing a radioac. decay
demo. for my
friend's Chem. class at N. High. I used his large TV, my new G4
portable, and Vernier's
rad. monitor, Logger Pro and Lab. Pro. interface -- the resolution was
worse than
unacceptable!

Did I do something wrong, or should the HS get a projection system, or
for less, a
hundred dollar camera, and have it look at my G4 screen?.

bc

P.s. The TV did not have S-Vid.


Michael Edmiston wrote:

John Denker mentioned pointing a camera at an experiment and projecting the
image on the screen. I often do that, and I can zoom in on any part of the
experiment, including any meters or scales being used.

John also mentioned one problem with this technique (other than money) and
that is the resolution of the camera. Elmo, or Viz Cam, etc. indeed have
limited resolution. When I need high resolution I take a picture with my
digital still camera, put the jpg picture on a laptop, and project it with
the LCD projector.

I used to have a 1.3 megapixel camera, but recently bought a 3.3 megapixel
camera. It is pretty amazing. I typically use Microsoft Photo Editor on
the laptop when I recall the jpg picture for projection. I do that because
it is easy to scroll around on the picture and zoom in on a particular
portion.

Here is an example. Students always have problems reading the scale on our
spectrometer. It reads in degrees and minutes, using a vernier scale to the
nearest minute. I take a picture of the spectrometer from overhead so that
the whole spectrometer fills the frame. Then, when I show this in class, I
zoom in on the scale, and there is plenty of resolution to teach them how to
read the scale.

I have taken several photos at specific scale readings that students often
goof-up. By going over these problem areas with specific photos, the
students make fewer errors when they are making readings on the own. It
might be a hassle to prepare the photos ahead of time as opposed to using a
TV camera live in class, but the resolution is better, and I have specific
example I want to use anyway, so in the end it works well.

Thus, when I have equipment or a lab to demonstrate, I typically use a
mixture of live TV shots and high resolution still photographs. Sometimes
one, sometimes the other, sometimes both. I have found this works as well
or better than having a group of students gather around me to see the
apparatus directly. Especially for things like vernier scales, the group
can't see the actual scale live unless I take the time to have each student
individually look at it. The high resolution digital photos solve this
problem very well.

Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817