Re: [OM] shutter speed

[Piers Hemy]

Inspection of the image shows blurred specular highlights on the mortar
round.  Measurement of the blurred highlights shows they have length 63% of
the width of the round.  Since we know that this is a 60mm round, we can
deduce that the round travelled 38mm (1.5 inches) during the exposure. 

Based on Chuck's muzzle velocity speed (it's as good as anything!) of 500
fps (6000 inches per sec) I believe the shutter speed was 1.5/6000 seconds,
which is 1/4000 sec.

Piers

-----Original Message-----
From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx] 
Sent: 21 December 2009 01:13
To: Olympus Camera Discussion
Subject: Re: [OM] shutter speed

Googling 60mm mortar muzzle velocity returns number between 439 and 550 feet
per second.  Let's choose 500 fps for a nice round number.  It looks to me
like the projectile is about 1 foot out of the tube so it started emerging
from the tube 1/500 second ago.  So I'll guess 1/1000 of a second shutter
speed which would allow it to traverse half it's length during the exposure.

Chuck Norcutt


John Hudson wrote:
> Is there any opinion on the likely shutter speed of this snapshot ?
> 
> http://tinyurl.com/y9or7zs
> 
> jah
> 
> 
> 
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