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Original Post

bomobob says

More Dirty Science

RTFM comes up a lot with reference to cameras, but unfortunately most manuals are written by geeks, for geeks. They’re so bad in fact, that even a pseudo-geek like me has a hard time with them.

For someone with ZERO knowledge of cameras (like 99% of the population), they may as well be in Latin. Or Canadian.

So in this class, I want to dumb down the entire camera manual, any camera manual, into two really simple concepts:

Shutter speed and Aperture.

I see Soap Girl’s eyes glazing over already in the back row. *Throws chalk at Soap Girl*

In spite of how complex they are, how much they cost, how big the manuals are, or who they’re made by, when a picture is snapped, only two simple things really happen. (OK, way more than two, but the rest we don’t care about now)

1. An opening in the lens (the Aperture) opens up a little bit or a lot to let in light

2. The shutter opens and then closes again, really quickly.

That’s it. That’s been it for 100 years.

The aperture opens up wide to let in lots of light, or it opens up just a tiny bit to let in just a bit of light.

Similarly, the shutter opens and closes slowly to let in a lot of light, or it does so really, really fast to just let in a bit. In film cameras, the shutter is like a little curtain that gets flung open to let light hit the film, and then closed very quickly. Digitals work a bit differently, but that doesn’t matter. The function is 100% identical.

So, the aperture is pretty basic. Lots of light (big) or a little bit of light (small).

The shutter does stuff we can relate to though. It’s exactly like opening your eyes. If you open them for 1 second, you see stuff happening around you. But if you just blink really fast, all you see is an instant frozen in time.

Shutter fast – just a blink of light, and frozen moment

Shutter slooooowwwww – light coming in for a long time, and lots of stuff moving around.

Your camera likes to have a balance of aperture and shutter speed because they both let in light. One determines how much, and one how long. So it balances them for you. If it uses a big aperture to let in tons of light, it will use a fast shutter speed. Conversely, if it uses a tiny aperture, it will keep the shutter open longer to compensate.

So here’s a little experiment you can just pretend to do.

You go to watch little Jimmy at his soccer practice. Luckily for you, little Jimmy really needs the practice because he’s a rubbish soccer player, which means he’s constantly running past you to get the ball. What a great opportunity. You set up your camera on the tripod and you take pictures of Jimmy as he runs past.

Let’s pretend your camera isn’t completely automatic. You set the aperture really small (very little light), and so you set the shutter to a long setting, maybe 1 second.

Here comes Johnny! Or is it Jimmy? Can never remember that kid’s name.

Click. There’s a picture of Jimmy, just looking like a transparent swoosh as he ran by. 1 second’s a long time.

So now you make the shutter faster, maybe ¼ of a second. Well, to get the same exposure as before, you need to open the aperture a bit to let in more light, since your shutter is now so much faster.

Click. Hey, Jimmy’s looking more like a little soccer player now. He’s blurred, but you can tell it’s him.

You’re already getting the hang of this. You set the shutter for 1/60 of a second, pretty fast. Of course you open up the aperture even more, and…

Click. Wow, he’s almost frozen in his tracks, with just some slight blur on his legs.

So now you set the shutter speed to 1/1000 of a second, super fast. That’s so fast in fact, you’ll have to open the aperture all the way.

Click. He’s perfectly frozen, leaping above the ground.

So all the while you had to keep trading of one against the other to get the same exposure every time. But if you wanted to change the exposure to make it brighter or darker, you now know there are a couple of things you could have done each time.

Want it lighter? Open the aperture a bit more than you did. Or, make the shutter a little bit slower to allow more light in. And the opposite if you wanted the pictures darker.

The good news is that for objects that don’t move, the shutter speed isn’t very important, so it’s one less thing to worry about.

Your camera always sets the aperture and shutter speed to get what it thinks is a perfect exposure. It has no idea what you’re taking pictures of or how you want them to look. But many very basic cameras do allow you to make little adjustments to the aperture and shutter speed, and thereby let you take in a bit more light, or a bit less.

Posted at 6:08pm Apr 19, 2010 EDT


Even though, I understand both Canadian AND Latin, I appreciate the translation!

Posted at 6:10pm Apr 19, 2010 EDT

thanks Bomo, have I joined this course in the middle of the semester?

Posted at 6:10pm Apr 19, 2010 EDT

bomobob says

peaseblossomstudio said:
Even though, I understand both Canadian AND Latin, I appreciate the translation!

Latin! Wow, good on ya!

Posted at 6:11pm Apr 19, 2010 EDT

Now I know and knowing is half the battle! Great info! Thanks!

Posted at 6:11pm Apr 19, 2010 EDT

So great of you to write this post! Honestly - I never, ever, ever thought that taking that photography elective in junior high would be such a big part of my life as an adult! I can honestly say that I use that a whole lot more than those 3 semesters of calculus in college!

Posted at 6:12pm Apr 19, 2010 EDT

That was me with the eyes glazing over. Reading the forums instead of working on my paper ...

Posted at 6:15pm Apr 19, 2010 EDT

WIAPilot says

VERY good photography lesson!

Posted at 6:17pm Apr 19, 2010 EDT

bomobob says:
peaseblossomstudio said:
Even though, I understand both Canadian AND Latin, I appreciate the translation!

Latin! Wow, good on ya!

4 years and all I remember, honestly is:

"Semper ubi sub ubi"

Posted at 6:18pm Apr 19, 2010 EDT

Wish you write a "Manual for Dummies"...I'd buy it! Great info and easily understood. Thanks much!

Posted at 6:18pm Apr 19, 2010 EDT