This week aperture is our hot topic of discussion. And it’s my favourite. So much of what I love about the creativity of photography is involved with aperture.
Your aperture controls how much light enters your camera through the lens. Practically this is done by blades inside the lens of your camera which are adjusted by the aperture dial in order to increase or decrease the opening or ‘aperture’ of your lens to let light inside. The size of the opening the ‘aperture’ is measured as an f/stop. The f/stop of a lens can go from as wide as f/1.2 to as narrow as f/22 or narrower. The range of your cameras aperture is dependent on the type of lens you have for your camera.
The confusing thing to remember about the f/stop measurement is that the lower the f/stop value the wider the aperture, and vice versa the higher the f/stop value the narrower the aperture.
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F/1.2, f/1.4, f/2 are wide open apertures which allow a greater amount of light to enter the camera. Because of this they are more convenient apertures to use in low light situations. A wide open aperture will result in a faster shutter speed (though this is dependent on available light). Due to the large amount of light flowing into your camera less of your photograph will be in focus.
F/16, f/22, f/32 are narrow or closed apertures allowing less light to enter the camera. Because they allow less light though your lens they may not be convenient in low light situations unless shutter speed is not an issue, or your camera is on a tripod. Less light is allowed through the lens opening but more of your photograph will be in focus.
F/5.6, f/7.1, f/8 are my ‘who cares?’ apertures allowing a moderate amount of light into the camera meaning that most but not all of your image will be in focus.
Let’s look at some of these apertures in action, so that you get a better feel for them.
In these images I placed some ‘granny smiths’ at equal distances apart on my kitchen table. With the camera on a tripod (I knew some of my shutter speeds were going to go pretty low), and my ISO set to a constant value of 1000; I took several pictures stepping up the aperture two steps at a time , and consequently the shutter speed two steps down (until the last image when I jumped a few more steps showing how narrow this particular lens would go).
1. Aperture f/1.8, Shutter speed 1/500th second, ISO 1000
2. Aperture f/2.2, Shutter speed 1/320th second, ISO 1000
3. Aperture f/2.8, Shutter speed 1/200th second, ISO 1000
4. Aperture f/3.5, Shutter speed 1/125th second, ISO 1000
5. Aperture f/4.5, Shutter speed 1/80th second, ISO 1000
6. Aperture f/5.6, Shutter speed 1/50th second, ISO 1000
7. Aperture f/7.1, Shutter speed 1/30th second, ISO 1000
8. Aperture f/14, Shutter speed 1/8th second, ISO 1000
As with last weeks lesson on ISO it may be hard to tell the aperture difference between each stage, but if we look at the first and last images side by side, we can see a more dramatic effect.
These images demonstrate that as the aperture becomes narrower more of the content of the picture comes into focus. The area of focus in your pictures is known as the ‘depth of field’. I’ve tried to show this with the little arrows in the images. Can you see that with an open aperture (a small value f/stop – f/1.8) that there is less depth of field? In other words the picture on the left has less of the images in focus. Contrastingly – can you see that with a closed aperture (a bigger value f/stop – f/14) that there is more depth of field? In other words more of the image in the picture on the right is in focus.
What does this mean for your images?
Generally I find that if I want a soft looking portrait image with a blurry background I want my aperture to be wide open (a low number – remember?). If I’m photographing a group of people, this won’t work, as my depth of field won’t effectively cover everyone standing at slightly different angles, so I’ll close down my aperture (increase the number).
A word about ‘Bokeh’
The magical effect of using a wide aperture and blurring the background is known in the business as ‘bokeh’. It’s based on a Japanese word meaning blur or haze. And it can look fab in portrait pictures. The quality of ‘bokeh’ you can produce with your camera is really down to the lens. But if you’re looking to create some in your next portrait picture just remember to keep the f/stop value low which means your aperture is wide open and therefore your depth of field narrow.
(check out the flowery daisy bokeh in this picture of Isaac)
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Next week we’ll be talking shutter speed, and then we’ll be finished with the magic three!
I’ll be taking a break for a month or so, whilst I focus on my Autumn family sessions.
But I’ll be back at Christmas time to talk about camera settings in general – aperture and shutter speed priority modes.
If you’ve enjoyed this week’s class, but missed the others check them out here …
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