Did you know that a typical built-in flash only illuminates about 4-10 feet effectively enough for a photo under most lighting conditions? Yet you see these people at concerts, zoos, sporting events, etc with their flashes going off on the camera when the subject is half a football field away. Clearly, they aren’t the science guys. 
But the geek of the matter is this mathy lil’ tidbit: the inverse square law.
{oh mah gawsh, she is NOT going to talk physics. Oh. Yes. I. Am.}
What is the Inverse Square Law?
It states,
… a specified physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity.
Yeah. Um, okey doke…
Let’s play picture pages instead.
So, let’s say you take an image and your flash fires. If the light is considered full strength at 1 foot away – what happens to the strength (or quality) of the light at 2 feet?
Double the distance, so half the light, right? Wrong.
At 2 feet, the strength of the light is 1 over 2 squared. 1 / 2^2 = 1/4. At 2 feet, light is only 25% of what it was at 1 foot.
At 4 feet, the strength of the light is 1 over 4 squared. 1 / 4^2 = 1/16. At 4 feet, light is only 6.25% of what it was at 1 foot.
Since at 10 feet away the light is only 1/100th or 1% of the strength of the flash… this means if your subject is 10 feet or more away, you’re not effectively lighting your subject, you’re pretty much just ticking off all the people around you.
Day 10 Tip: Just turn off the silly flash already.
xo.
amen
amen
Ha! Now I know why my son asked to go to public school his senior year to take honors physics. Smart boy.
Oh? Great information that I learned here… Thanks for the post!
LOL!!!!!!!!!! Love it♥
haha…thanks! I was pretty happy yesterday when I took a pic of an older couple and the man asked me, “Don’t you need the flash?”
I took some surprisingly good images inside of cats using a business card to reflect the flash up. No squinty eyes and no harsh flash look.
This is a great way to modify light.
LOL! Ha ha ha! Love it!
I’m learning to not use my flash (C:
That needed to be said, thank you! I will take the homework assignment for tomorrow
Also, I linked….
http://belovedmusephotography.blogspot.com/2011/10/day-9-get-off-computer.html
Amen Sista! I cringe watching people use flash against glass at aquariums and the like.
I get so mad – once in awhile my flash goes off(meaning ON) even when I’ve turned it off (meaning OFF) – I’m working with a ‘lil point -n-shoot that actually does a great job, when it obeys!
I’ve been able to get shots for magazines and news posts and lots that I’m just tickled with. It’s been a wonderful learning tool for me. Look forward to getting myself the “real deal” one day, but I’m plenty happy in the mean time. Your tips are mighty helpful! Thanks- (also loved your recent web-inar)
Hallelujah!!!! My daughter is a high school cheerleader, so I go to TONS of sporting events, both inside and outside. I can’t believe how many people think their little flash is going to help their pic of their kid on the football field.