This month’s challenge was to start understanding the ‘Triangle Of Light’, beginning with aperture. The main idea was to show what the effect is when your aperture is increased or decreased, particularly when close to the subject of the photo.
This is the setup I employed:
And here are some of the photos I took of my Lego workforce:
Focus set on nearest worker.
Aperture set to f2.8 (the maximum my 17-55 lens will allow). As you can see, yer man in front is nice and clear, but his pals at the back are turning into shapeless orange blobs.
Aperture set to f9 (around the middle of the range). Now you can see his mates starting to come into focus, but the ones at the back still aren’t really with it.
Aperture set to f22 (around the top of the range). My workforce is all present and correct now, ready to head off to dig up a yellow brick road…
Focus set on worker in the middle.
Aperture set to f2.8. In this set up we can see our central character clearly, but his mates are blurring outwards from the centre.
Aperture set to f8. Now yer man’s got a few more people clearly visible to play with, but the extremities are still blurred.
Aperture set to f22 (around the top of the range). There they all are again!
Here are some I took in a pub in Ireland a couple of years ago of a band that came in at the weekends to entertain people. As the trip was with a group of photographers (for the most part Irish) the entertainment was ripe for a million photos, hence we were scrambling around to get good angles (whilst sneaking in paparazzi shots of each other in as compromising looking positions as we could get) while the ‘foreign’ visitors were mesmerised by the music. I don’t think this was the year that the very large German threatened to stuff my friend’s camera where the sun didn’t shine, as it looks like I was sitting in a different part of the pub, but in case you were wondering, it was because he didn’t like flashing…
As you can see though, the group are a distance from me, and I was using the wide aperture in order to let in as much light as possible, since it was a very dark and gloomy pub, and my mammy told me not to flash strange men.
Focal point – violinist
Aperture – f2.8
Shutter Speed – 1/30
ISO – 6400
In this second shot I had a musician much closer to me than the rest, so the effect that we saw in the initial part of the challenge comes into play here, with the closer guy out of focus:
Focal point – violinist
Aperture – f2.8
Shutter Speed – 1/15
ISO – 6400
I also used a wide aperture to get this photo in the dark and gloomy cloisters at Glasgow Uni because I hadn’t humphed my tripod up there:
Focal point – 2nd column down on the right
Aperture – f2.8
Shutter Speed – 1/25
ISO – 1600
For the zoomed in effect, I took my camera with its long lens to the Kelvingrove Art Gallery And Museum a few weeks ago, because they have a set of heads just hanging around which are ideal to show the long zoom + aperture effect. Unfortunately they play a range of coloured lights over them, as well as having tungsten bulbs above, so they can be rather tricky to photograph. as you can see though, everything behind them is blurred, even though the minimum aperture my lens would allow at the zoom I’d chosen was f4.5
Focal point – head
Aperture – f4.5
Shutter Speed – 1/40
ISO – 1600
So why does this happen, and what do all those weird numbers mean anyway?
Okay, I know I said I wasn’t going to get too scientific, but there’s a couple of wee bits of information you’ll probably find useful.
Firstly the effect of aperture and the focal plane:
This was what we saw in the first part of your experiment where areas of the photo were blurred. If you are facing something head on, the focal plane of an object is considered to be everything that’s exactly the same distance from you as that object – so for example a wall is a focal plane, but a shelf on the wall would be on a different focal plane as it’s nearer to you.
The effect on your photos is related to the angle in which the light goes from the subject being focussed on to the lens. When the aperture is wide open, the angle is large and there’s very little else able to make that same angle if they are outside the focal plane of your object. As the aperture closes down, more things are able to make the same much smaller angle outside the focal plane of your object.
Secondly, the use of aperture to let in more or less light:
Lens aperture is akin to how your iris works automatically to let more or less light in. Try shining a bright light in someone’s eye, and you’ll see their pupil shrink down. Put them in a darkened room and their pupil will get much wider. In a similar way, if you are on automatic mode the blades which create the aperture open out in the dark and narrow down in bright lights.
The aperture numbers represent the area of the lens that is open, and the ‘f’ stands for the ‘fractional area’ of the lens being used. Most cameras these days actually operate in fractions of an ‘f-stop’, but here are the ‘whole stop’ values, where f1 is wide open.
Your camera may do increments in ⅓ or ½ stops, and in fact in DSLRs you may have the option to choose how you do it. I personally have mine in ⅓ stops. I also have no idea why they’re called stops…
For the super nerdy:
You may or may not recall how to calculate the area of a circle from those dim and distant maths classes you took when you were about 12, but the fractions in this case are a division by √2 (approx. 1.41) for each ‘f-stop’, thus the lowest aperture setting available on a lens is generally f1.4.
Where the two equivalent forms are related via the f-number N = f / D, with focal length f and aperture diameter D.
What settings should I use and when?
There are absolutely no hard and fast rules to what you should use and when, but the following are a good rule of thumb:
- Landscapes – f11 and above – this will give ‘front to back’ clarity, and the main focal point should be around 1/3 of the way into the scene in order to be able to achieve this. This is assuming that you haven’t got a ‘foreground point of interest’, but we’ll worry about the arty farty landscapes at a later date ;o)
- Portraits – f1.4 – f5.6 – this will depend on how your subject is set up and whether you’re employing props etc, but these values should give you those nicely blurred backgrounds. Make sure you don’t choose something so shallow that your subject loses their ears or hair though!
- Macros/close ups – here it becomes a little controversial depending on what your subject is – some prefer the nice wide apertures showing one tiny thing in focus, others like to see their insect, or whatever, in full focus and so use narrow apertures. Have a play and see what you prefer.
Depending on your choice of subject you may need to invest in a tripod in order to achieve your desired aperture, for example landscapes at sunrise/sunset can have surprisingly long shutter speeds which you won’t be able to hand hold.
Now let’s see what you’ve been up to:
Excellent as ever. There's just one wee bit I'd add for the curious.
Some people ask, "Why are f-stops needed?" In the same lighting conditions each f-stop allows the same amount of light through for a given shutter speed and ISO, regardless of the focal length of the lens. So if I measure the exposure needed at ISO 100 to be 1/125s at f8, it doesn't matter if I'm using a wide-angle lens or a telephoto.
This is how it works. The f-stop is the ratio between the aperture (strictly – the entrance pupil) and the focal length in use. So on my 24-105mm at f8 lens the aperture varies like this:
At 24mm the aperture is 24/8 = 3mm in diameter
At 48mm it is 48/8 = 6mm in diameter
At 96mm it is 96/8 = 12mm in diameter.
If I was using a 400mm lens, the aperture at f8 would be 400/8 = 50mm.
What's important is that the amount of light hitting the sensor in 1/125s is the same in all cases, but it does mean that the longer the focal length, the more like a bazooka a lens becomes. There's a Canon 600mm f4 lens for a cool £8,900 and it is 600/4 = 150mm (6 inches) across. So next time you wonder why sports and wildlife photographers have such huge lenses it's just the laws of physics!
Enjoy your photography!
I was doing alright until I saw mathematical equations and then my eyes glazed over! Haven't done my homework yet but I will 🙂
This is so helpful and interesting. I am so behind, too. I am going to see what I can photograph this weekend. I love that you dad is adding his insights too, although I might have to read them over about 100 times to really understand. I like the lego men, your set up truly helps me understand your explanations. And I love your photos, they are great.
May I inquire as the the super high ISO settings for the pub shots? Was it really dark in there? Does that impact the graininess of the imagines. Just wondering, I'm not used to going so high on my ISO. Thank you for another wonderful lesson!
This is an awesome series and I look forward to the next
The science bit still confuses me, but I loved taking the photo for this challenge, although it was like lego dominos every time I knocked the foam board!!
That photo from Glasgow Uni is stunning and brochure worthy!
Great post. I really need to catch up with this series. If not before, I'll catch up during easter. Too late to link up, to the individual challenges, but learning all the same
I would echo Melissa's question above. Why aren't your photos at high ISO grainy?
When I started this series this morning I had ISO still on automatic and the camera's choice was 800, which I thought was far too high. Reason tells me that 800 isn't there for nothing and yet I set exposure compensation at +1 (and forgot to move it back) and then moved the set up to a lighter position and set ISO on 200. I wonder where I got these crazy ideas about ISO from!