Date: Mon, 14 Feb 2011 10:34:19

Author: Brian Holton

Subject: Re: High Speed Video advice

Post:

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Thanks guys, I will try more light. I don't know, my logger pro 3.7 opened
the .wmv file but showed nothing - just a white screen. By blue I mean the
moving object was blurred, not the picture. Perhaps a brighter light will
kick the camera into a faster mode. Will try. A manual shutter speed would
be nice, all I have is my Logitech webcam... but could get something else
if someone recommends.



Thank you again,

Brian





From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Paul Nord
Sent: Monday, February 14, 2011 10:10 AM
To: tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] High Speed Video advice



Brian,



If there was no blur in your .wmv file, then certainly look into other
conversion software.



More likely, you need a camera with a manual "shutter speed." I put that in
quotes because there is no real shutter in a video camera. Rather, it is
the time it takes the ccd to go through a clear-expose-read cycle. Many
many cameras adjust this automatically for you to give you what they
consider to be the "best" shot. Setting a shutter speed that is too short
tends to give you a fuzzy image as a result of the signal to noise ratio on
some of the dimmer pixels. However, a typical video image for general
physics has WAY more information than required for good analysis. Even on a
slightly grainy image you can still pick out the position of the cart or
ball to within a pixel or two.



Another solution which may fix your current camera: LOTS more light. Add a
250 W spotlight. Try two or three and you'll start to get close to the
brightness of direct sunlight. Your camera may automatically adjust to
1/250 second or faster shutter speed. That's fine for most lab experiments.



Years ago we purchased a great new video camera for the lab. It had an
"automatic sports mode" to capture fast action. Well, it seems that "sports
mode" took a couple of seconds to kick in and/or it was not trigged by a
small projectile moving across the screen. It was absolutely worthless for
our purposes. Most freshman physics is only true for about 2 seconds.
After that you have to start thinking about non-linear friction, air
currents, and heating losses. We sent it back and got the next cheaper
model which had a manual shutter adjustment.



Paul





On Feb 14, 2011, at 8:43 AM, Brian Holton wrote:





Hey everyone,



I am planning on taping some physics experiments to analyze in Logger Pro.
I've been using my webcam that saves videos in .wmv format, then I convert
them to .mov format for logger pro using AVS Video Converter 7.1. The frame
rate seems to be 15 fps.



Even with an airtrack moving at "normal" speeds, I get blur. I've seen some
videos posted out there for physics analysis, and they have blur. That's
just not cool.



I know someone out there knows how to video and process without getting
blur. Advice is greatly appreciated! I take it I will need a faster camera
(which one?) and maybe some different software to convert to .mov?



Before I buy AVS Video Converter 7.1 (I am using the free version right
now), is there any other program one would recommend? (windows please)
Cheap.



Thanks in advance folks,

Brian Holton

Passaic County Community College, NJ




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Thanks guys, I will try more light. I don’t know, my =
logger pro 3.7 opened the .wmv file but showed nothing – just a =
white screen. By blue I mean the moving object was blurred, not =
the picture. Perhaps a brighter light will kick the camera into a =
faster mode. Will try. A manual shutter speed would be nice, =
all I have is my Logitech webcam….. but could get something =
else if someone recommends. Thank you again,Brian From:=
=
tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On =
Behalf Of Paul NordSent: Monday, February 14, 2011 10:10 =
AMTo: tap-l@lists.ncsu.eduCc: Paul =
NordSubject: Re: [tap-l] High Speed Video =
advice Brian, If there was no blur in your .wmv file, then certainly =
look into other conversion software. More likely, you need a camera with a manual =
"shutter speed." I put that in quotes because there is =
no real shutter in a video camera. Rather, it is the time it takes =
the ccd to go through a clear-expose-read cycle. Many many cameras =
adjust this automatically for you to give you what they consider to be =
the "best" shot. Setting a shutter speed that is too =
short tends to give you a fuzzy image as a result of the signal to noise =
ratio on some of the dimmer pixels. However, a typical video image =
for general physics has WAY more information than required for good =
analysis. Even on a slightly grainy image you can still pick out =
the position of the cart or ball to within a pixel or =
two. Another solution which may fix your current camera: =
LOTS more light. Add a 250 W spotlight. Try two or =
three and you'll start to get close to the brightness of direct =
sunlight. Your camera may automatically adjust to 1/250 second or =
faster shutter speed. That's fine for most lab =
experiments. Years ago we purchased a great new video camera for =
the lab. It had an "automatic sports mode" to capture =
fast action. Well, it seems that "sports mode" took a =
couple of seconds to kick in and/or it was not trigged by a small =
projectile moving across the screen. It was absolutely worthless =
for our purposes. Most freshman physics is only true for about 2 =
seconds. After that you have to start thinking about non-linear =
friction, air currents, and heating losses. We sent it back and =
got the next cheaper model which had a manual shutter =
adjustment. Paul On =
Feb 14, 2011, at 8:43 AM, Brian Holton wrote:Hey everyone, I am planning on taping some physics experiments to analyze in Logger =
Pro. I’ve been using my webcam that saves videos in .wmv =
format, then I convert them to .mov format for logger pro using AVS =
Video Converter 7.1. The frame rate seems to be 15 =
fps. Even with an airtrack moving at “normal” speeds, I get =
blur. I’ve seen some videos posted out there for physics =
analysis, and they have blur. That’s just not =
cool. I know someone out there knows how to video and process without =
getting blur. Advice is greatly appreciated! I take it I =
will need a faster camera (which one?) and maybe some different software =
to convert to .mov? Before I buy AVS Video Converter 7.1 (I am using the free version =
right now), is there any other program one would recommend? =
(windows please) Cheap. Thanks in advance folks,Brian HoltonPassaic County Community College, =
NJ
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From tap-l-owner@lists.ncsu.edu Mon Feb 14 10:43:15 2011

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