digital images

Joseph Laferriere josephl at CCIT.ARIZONA.EDU
Wed Aug 23 13:27:22 CDT 1995

My Proboscidea fruit would have taken a flash as powerful
as a solar flare to reach a 1/90 sec exposure time. I was using black and
white film, so color distortion was not a factor. A third method for
decreasing exposure time would be to use faster film. ASA 1000 film is
commonly in use today.

On Wed, 23 Aug 1995, Alan Harvey wrote:

> Joseph Laferriere wrote:
> >The problem is that the smaller the aperture, the longer the necessary
> >exposure time. I once took a picture of the fruit of a Devil's claw
> >(Proboscidea sp.) with a necessary depth of field of over 3 cm. The
> >camera needed such a small aperature that it required a 60-second
> >exposure. It came out beautifully. A video image is really a series of
> >still photos shown in rapid sequence. The very nature of the medium
> >prevents long exposure times.
> Actually, the smaller the aperture, the less light reaches the medium per
> unit time, which can be compensated for by either increasing the exposure
> time OR increasing the intensity of the illumination.  E.g., in
> photographing the Devil's claw fruit you could have gotten the same depth
> of field with a more typical 1/60 -1/90th second exposure with a strong
> enough flash (and without the color shifts due to reciprocity failure that
> often result from very long exposures).  Still, still cameras probably are
> more flexible than video cameras in both respects (exposure duration and
> light intensity).  Does anyone out there know how to synchronize a
> framegrabber/video system with a flash unit?
> Alan
> ------------------------------------
> Alan W. Harvey (aharvey at
> Assistant Curator of Invertebrates
> American Museum of Natural History
> Central Park West at 79th Street
> New York, NY 10024
> (212) 769-5638

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