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View Full Version : A Really, Really Dumb Question

chuckinsocal
Sep-25-2008, 12:54 PM
So dumb I'm almost afraid to ask.

When someone says "stop down the aperture", does that mean reduce the aperture value thereby enlarging the opening or does it mean to reduce the opening by increasing the value :dunno?

It's ok, you can go ahead and laugh at me now :giggle.
OhEddie
Sep-25-2008, 01:00 PM
The way I've always understood it was, when you stop down a lens, you are going to a larger number/smaller aperture and therefore less light. Going from f/8 to f/11 is stopping down. The opposite is opening up; going from f/11 to f/8 is moving towards the smaller number/larger aperture and therefore more light.
Red Bull
Sep-25-2008, 01:01 PM
It means to increase the aperture value which reduces the opening.
digismile
Sep-25-2008, 01:01 PM
If only it were a dumb question :D. I expect that this is one of the most often confused statements we encounter.

I take this to be "increase the value and decrease the size of the opening/light".
swintonphoto
Sep-25-2008, 01:05 PM
The way I've always understood it was, when you stop down a lens, you are going to a larger number/smaller aperture and therefore less light. Going from f/8 to f/11 is stopping down. The opposite is opening up; going from f/11 to f/8 is moving towards the smaller number/larger aperture and therefore more light.

Yep. Thats it.
cmason
Sep-25-2008, 01:15 PM
Yep. Thats it.

I always find this to be the most useful read on the subject, so keep it close by for review:

http://www.uscoles.com/fstop.htm
chuckinsocal
Sep-25-2008, 02:02 PM
Wow ... thanks Chip. That's one of the best reads ever on exposure, f stops and all that. I'd highly recommend it.

And thanks to everyone else for clearing all this up. Now I can go on with confidence that I think I know what people are talking about and I actually might know what I'm doing sometimes :thumb.
georges
Sep-26-2008, 05:39 AM
This is a lot easier than most people think.

F/stops are fractions. The F stands for the focal length of the lens.

If you're using a 100mm lens then f/8 and f/16 are really 100/8 and 100/16.

If you're using a 35mm lens then f/8 and f/16 are really 35/8 and 35/16.

It's not hard to figure out which one is bigger.

The lens and camera makers just use the denominator to save space. The "f/" is assumed to be understood. Of course, for most, it's not.