Chronos > Chronos User Discussion

Exposure time setting.

(1/2) > >>

hsmore:
    I am running Chronos 1.4 with standard 12.5-75 zoom lens, f 1.2-16, 3.5ft-infinity focus.
I am running 12,578 frames per second and 320x320, 1x gain, .  My only question is:  What exposure-value
do you recommend using ?  According to the camera,
I can set the exposure to anything between 1 and 79.49 microseconds.  I think I have been using
about 14.7microseconds in the past.  But, what value should I be using ?  (The subject is a projectile at 2400 feet/second.)   

hsmore:
Well, I guess I will try to answer my own question.  Use as few microseconds of exposure as possible while still getting enough light to capture your video.  The larger the exposure-time, the more motion-blur you will get in your frame images.

wilkinsonwilfrid:
I suppose I'll attempt to address my own question.  Get enough light to record video with the fewest microseconds of exposure feasible.  Your frame photographs will exhibit greater motion blur if you increase the exposure time.

garagesip:
Use exposure within as few micrometers as possible while still having enough light to capture video. The longer the exposure time, the more motion blur the image in your frame will have. You can set the exposure to anything between 1 and 79.49 microseconds.

Rob_G:
Hi Hsmore,

Seems like you are running an interesting experiment to capture the flight of a supersonic projectile.

You need to know the physical size that corresponds to each pixel, also referred to as the resolution, in your field of view.

As an example, if the physical width of your field of view, 320 pixels, is 5 m, then the resolution of your imaging system is

5m/320 pixels = 0.0156m/pixel or 15.6 mm/pixel.

Blurred motion is seen when the object captured travels more than 1 pixel during the time the camera ir recording.

Next, you can compare the time, t, it takes the object to travel a distance equal to the size of 1 pixel.  t = 0.0156m / 731.5m/s = 21.3 µs.

You can set your exposure time to 21 µs.

If the exposure time is longer then you get blurred motion. If you set it lower than 21 µs you avoid blurred motion but you also require more light to illuminated the scene adequately.

Note that this number is based on the assumption that your filed of view is 5m. Estimate your exposure time based on the actual size of your field of view.

Navigation

[0] Message Index

[#] Next page