Exposure Time

January 17, 2008

Interesting comment made in one of the podcasts at http://podcast.eastmanhouse.org/ .  The curator of photography threw out the number 400,000 as an estimate of how many photographs the Eastman House has.  Interesting but nothing really special in that number.  But then he suggested you think about that number in terms of the TIME captured.  Early photographs were seconds to minutes.  20th century photography is mostly sub-one second times…

Just for fun, lets say the average is one second.  400,000 photographs = 400,000 seconds

400,000 / 60 / 60 / 24 = 4.63 or just about 4 and 2/3 days of “TIME” captured.

Take this one step further…  I seem to remember a number like $50 Million as the total sales of digital cameras in a recent year.   Lets say the average camera cost is $300 so that is over 160,000 new cameras in a year.  Another guestimate might be that on average there are 5 exposures made per camera per day for a year.  I picked this to cover both the occasional shooter that makes 10 or 20 snapshots per year and the working professional that is making possibly hundreds per day.  And each exposure is on average 1/100 of a second.

So just for those 160,000 “new” digital cameras, in one year:

160,000 x 5 x 365 / 100 = 2,920,000 seconds which is a little less than 34 days captured.  Push the average exposure time up to 1/500 and that time drops to 6.8 days…

This isn’t scientific and it isn’t really what is happening with time but to me it is an interesting way of considering what happens to all the images made (digital or film) over time.


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