Hey everyone, happy Wednesday! Hope you all had a great day! Today’s post has been written by our amazing guest blogger Lindsay Shaw Lehmann. If you missed her intro you can check it out here. So without further ado, here it is. Enjoy!
Ooooh, a Blog on Aperture. What a treat. I love aperture. To me, it’s fascinating.
Aperture is one of the three aspects of exposure that is controlled through the lens in your camera. For some users manual exposure may seem scary, and if you’re just picking up your camera for the first time, or you’re shooting on the fly and don’t have the concentration to control your camera in manual mode, you can shoot in one of your priority modes.
I’m a Nikon shooter (the best camera in the world J ) Just kidding, but on my camera Aperture Priority it is noted as “A” on the mode dial, or control panel. On a Canon it is noted as “AV” in the same places. Take a minute to check out your camera or its manual and find out where your Aperture Priority mode is.
Now, when you shoot in one of those priority modes, your camera is going to allow you to control which aperture you’d like to use while calculating which shutter speed is appropriate to create an average grey picture. In manual mode, you need to calculate this exposure on your own using your light meter to guide you. In Aperture Priority, this calculation is done for you in the camera. Easy, but if your scene is NOT average grey, then you’re going to need to adjust in the computer afterwards, or shoot in manual mode.
So, why would I want to control my Aperture. What is this silly thing anyways? Well, as previously noted, aperture means “hole”, and just like your pupil reacts to light, your aperture changes sizes depending on how much light is in your scene. If you were operating in fully AUTOMATIC mode the following scenario would take place.
If the light is bright your scene your camera may want to use a small aperture to eliminate the amount of light that comes onto your film or your CCD (Charged Couple Device- the light sensitive material in the back of your digital camera that records your image and sends the information over to your disc)
Conversely, if the light in your scene were dark, your aperture would open up to allow more light through the lens and onto your CCD.
(All this happens while your camera is calculating a BASE GRAY or MIDDLE GRAY exposure.)
Much like everything else in photography, the Aperture does not only control the amount of light that comes through the lens, but it also controls DEPTH OF FIELD. Depth of field is often misunderstood as how sharp your focus is. DEPTH of FIELD does not control HOW SHARP your FOCUS is. It controls how much focus is in your photograph. Your photo will only be in focus if you focus sharply on a particular point. Depth of field is how far in front of and behind that point of focus is. So, when you see those cool photos where the subject is in focus and the background or foreground is out of focus, that’s controlled by DEPTH OF FIELD through your APERTURE!
Back in the day (“when I was young, I’m not a kid anymore, but somedays I like to think I was a kid again”- don’t you just have to sing that song when you hear that phrase?) the fully manual cameras had a button called the “depth of field preview button”. When you pushed it, the aperture in the lens closed down and you could see, rather darkly, what your depth of field would look like at that particular aperture. If you wanted more or less you adjusted for it. Now a days with digital, you have to take several photos and see which you like best. This is called bracketing: it will be part of your assignment. Unless you have one of those fancy-schmancy buttons, you’re going to have to test it!
How does it work: Well it’s a lot of quantum physics, no really, it is a physics thing, which I don’t want to bore you with now, but if you’re into the science of it, it’s all about the bending of light through a central point and how quickly the rays of lights break off from each other determines how quickly you will lose focus from that central point.
In English: The smaller the whole, the greater the focus- or depth of field.
The larger the hole, the less the focus- or depth of field.
How do I know the hole size? The larger the number: the smaller the hole (the greater the focus-or depth of field)
The smaller the number: the bigger the hole, (the less the focus or depth of field)
What does that look like?
Check out the following example:
So, back to the good stuff: How do you know which aperture will best fit the depth of field that you want for your photograph. Well, there’s no real way to tell unless you have a fancy lens with a depth of field guide near the focus dial. That would tell you your range. So if you have one, good for you, use it. If you’re like the rest of us and don’t, here’s what you have to do.
Start with a number: if you want a shallower depth of field, choose a lower number 1.4, 1.8, 2, 3.5, 4.0, 5.6. If you’re looking to shoot a subject where most everything in the frame is in focus, then choose a higher numbered depth of field: 8, 11, 16, 22, 32, 45, 64. If you’re shooting in aperture priority mode then as you change your aperture, your shutter speed will correct for light gain or light loss. (remember as you change your aperture to a higher number less light will come in through the lens, and as you change your aperture lower, more light will come into the lens, if you (in manual mode) or the camera (in priority mode) does not compensate for this light change, then your photo will be over or under exposed.) If your camera tells you LO it means that there is too little light coming through the aperture to create a base gray image. If your camera tells you HI then it means there is too much light coming through and your image will be over exposed. If you need to compensate for light gain or loss through your ISO (sensitivity).
So, use your depth of field to enhance your photos. Most of you have probably been doing that already without really knowing what you’re doing. It just happens, but now you know how and why it happens, so you can control your images in the future. Happy Shooting and good luck! You won’t need it, you’re amazing, all of you!
-Lindsay
Now onto your homework, Lindsay and I challenge you to submit a photograph in which you have used depth of field to enhance your image. You can email your entry to beth@bethbenoit.com. One entry per person. All entries must be submitted before midnight on Sunday, April 2nd. Lindsay and I will judge them and choose one winner who will receive a $50 Beth Benoit Photography gift certificate. So get busy shooting and have fun!
P.S. All entries will be featured on the blog for What’s that Wednesday next week.
I learned on Canon, but had to make the switch when I was in college. I really liked the simplicity and layout of the Nikon D90. My first Nikon. But honestly, I teach Canon at Pomfret, and these days, they’re really both comparable.
