understanding and conquering the f/stop

by Mary Jane

Post image for understanding and conquering the f/stop

When learning photography, I think one of the biggest mistakes you can make is trying to learn too much, too fast. It’s a process. The more that you can slow down, breathe and enjoy the process – the sooner everything will come together and “click”. We’ve been learning that exposure is made up of a love triangle of sorts (ISO, f/stop and shutter speed). But, today, I just want you to ponder the ever so mighty f/stop. Forget about shutter speed, ISO, white balance, focus, or whatever is keeping you up at night – just for a bit.

In the illustration below, at f/2.0 the lens is wide open (you can see that none of the shutter is covering the opening). Because none of the opening is being covered, the most amount of light will be let in at f/2.0. As you go up in f/stop you can see that more and more of the opening is covered, letting in less light. The illustration also shows that the depth of field is greater as you go up in f/stop. This means that more of the photo will be in focus as you close down your shutter. At f/2.0, a very small fraction of the photo will be in focus – probably whatever your focus point is on and that’s it.


I took these photos to illustrate how an f/stop effects the look of a photo. Until you understand the aesthetics that different f/stops create, how could you ever know which one to choose for any given situation? So, I want you to look at these photos and study the subject but more importantly, the background.

What is happening to sweet Piper’s face (besides the fact that she is loosing it, ha!)? What about the background – what is changing? Which photo do you like the best – and why? Once you observe and answer these questions you’re that much closer to understanding the beloved f/stop.

f/16

f/9.0

f//5.6

f/3.5

f/1.8

f/1.2

If you’re like me, you probably love the look of the wide open shot the best. There is just something amazing about the soft, buttery look of the skin & hair and especially the blurred background. The only part of the photo that is in sharp focus are her eyes. I just love it! But, that doesn’t mean that I always shoot wide open – far from it, actually. If I am photographing an extremely active toddler that can’t sit still and is constantly jumping and moving, I’ll likely stop down a bit to at least f/2.8. If I am shooting more than one child and want both of them to be in focus I may stop down to around f/4.0. I leave anything past that (f/5.6-f/16) to group shots with lots of people, landscapes or architecture. For what you’re wanting to do, any f/stop from wide open to f/4.0 is going to suit you perfectly. You just have to decide what you want in focus and of course the lighting situation always plays a part as well – but that’s an entirely different blog post, for another day. 🙂

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{ 3 comments… read them below or add one }

chanell Smith July 3, 2013 at 4:46 pm

Wow! Seeing it illustrated like that really helps me understand how it all works. Thank you so much!

Mary Jane July 3, 2013 at 4:58 pm

I’m so glad! Sometimes it just helps to see them all next to each other.

Mia Humphrey January 10, 2014 at 7:38 pm

Thank you, Thank you, Thank you!!! I’ve searched hi and low to understand the f and did it in plain english!!! 🙂

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