Last month my wife read "Look Me In the Eye" by John Elder Robison (whose younger brother Augusten Burroughs wrote "Running With Scissors"). My wife couldn't put the book down...(and she's a slower reader than I) so I had to wait a day and a half to find out what she kept laughing about.

When I got the book...I read it cover to cover in one sitting (9 PM to 2 AM). Just couldn't put it down.

Since then, I've been a fan of John's blog...and yesterday he posted about needing to know math for operating a camera 60 years ago vs. just knowing "rules of thumb" today.

Check out his post...

http://jerobison.blogspot.com/2008/03/came...ath-skills.html

I think his point about letting machines do all of our calculations is certainly a good topic of discussion for digital photography especially for those of us who learned to shoot on those old...whatchacallit things...yeah, manual film cameras!

Anyway -- I recommend John's book for anyone who wants a good book recommendation where it doesn't have to be photography or business or self-improvement related.

Carry on.

This problem shows up in restaurants all the time in miscounted change. My uncle had a high school kid working for him during the summer's at an hourly wage. He'd worked 10 hours and couldn't tell my uncle what his earnings were.


EDIT: To answer your question ahead of time Dan....no...the kid was not I.

I'm on to ya' Fletcher...now if you would have said "my uncle's nephew..." you might have lost me...for a minute...

From the blog...




Uhm... it's hard to take seriously a blog that complains about math when the complaints are inaccurate.

The old rule still applies. When you are dealing with 2 significant digits as input, your answer can't be any more precise. f/2.8 is actually more like f/2.83. But that would be silly to engrave on a camera lens. So it's rounded to 2.8.

2.8 ^ 2 / 2.0 ^ 2 = 2.0. Same as when you double it.

If you want to use more digits, that's fine, too.

2.83 ^ 2 / 2.00 ^ 2 = 2.00. Same as when you double it. Go figure.

That said, I heard on the radio that two out of three adult Americans (roughly 75%!!) are numerically illiterate.


Eric

My brain hurts.

Count me in as numerically illiterate.

Eh, it's photography. Why not round? The difference between 1.96 and 2 really isn't going to be significant to matter here. If we were talking about designing a bridge or something similar, then I'd agree that the .04 difference could matter. (Coming from the perspective of someone that is 3/4 of the way through a math degree.)

A bit late but can't help myself...

Difference of 0.04 amounts to about 0.029 stop of exposure, or about 0.00067 sec of shutter speed, coming from 1/60. So yeah, I don't have that kind of control on my camera.

By the way, 1/125 isn't exactaly half of 1/60. What's with that?