Ok so you’ve agonized over the decision, read reviews, questioned your friends and family and you finally went out and bought that dream SLR you’ve had your eyes on. You rip open the box, pick it up, and you realize you have no idea how it works. Yes, if you push the shutter button (provided it’s got a battery and memory card in it) it will probably take a picture. But do you have any idea how that picture is going to come out? How can you make that picture look like the one that you meant for this new and fancy camera to take?
Your camera can’t read your mind. It doesn’t know what kind of picture you want to take. So chances are it’s going to play it safe. It’s going to try to get all of the picture in focus (so that your subject is in focus) and it’s going to shoot for an even and predictable exposure (because that’s what its little camera computer brain is programmed to do). In order to take the kind of picture that YOU want to take (and not the one your camera wants to take) you’re going to have to learn a little bit about how your camera and photography in general work. I know it sounds daunting but it’s really not that bad and we’ll take it slowly. Promise 🙂
First things first, exposure. Exposure is the result of three elements all working together: shutter speed, aperture, and iso. I’m going to explain them all very briefly and we’ll come back to each one later in a separate post (because goodness knows that all there is to learn about exposure could fill a book… or several… and does)
First up is shutter speed. This is the one you are most likely to already know a little something about. Shutter speed is simple. It is the length of time that your camera’s shutter is open for when you’re taking the picture. Take a picture at a fast shutter speed and it will “freeze” the action. Take a picture at a slow shutter speed and chances are it will be blurry. A quick and dirty rule of thumb is that if you are trying to take a picture handheld (aka you’re not using a tripod) the ABSOLUTE slowest shutter speed you should ever use is 1/the focal length of your lens. I know we haven’t gotten to focal length yet but say you’re using a 50mm lens. You couldn’t take a steady picture slower than at 1/50th of a second. I promise we’ll get into it more later but for now just stay above 1/60th an everything will be groovy 🙂
Next up is aperture. This one is a little trickier but you probably know more about it than you think. When your camera’s shutter opens it doesn’t always open the same amount. The amount that it opens controls the amount of light that comes into the camera at one time, so the bigger the opening the more light, smaller opening less light. The increments of aperture are f-stops. It would be nice if the bigger the f-stop number the more light but it’s actually the opposite. Bigger number = smaller opening = less light. Lenses that open wide (less than f 2.0) cost more and are generally pretty desirable pieces of equipment. Your”kit lens” that came with your camera probably doesn’t open any wider than f 3.5 which is why I always recommend getting another lens with a wider aperture. Canon makes a great “thrifty fifty” 50mm lens that goes to f 1.8, but equipment suggestions are for another day 🙂 There’s one more catch about aperture that I haven’t mentioned yet and that is what the change in aperture does to the picture besides controlling the amount of light. Aperture is one of the major contributors to something called “depth of field” which is (to put it very simply) the range of distance in front and behind your subject that is in focus. The wider your lens is open the more opportunity there is for the background and foreground of your shot to be out of focus. This isn’t a bad thing. This is how photographers get that great separation between their background and subject and make everything else look “fuzzy”. It’s something that takes practice to control (and needs way more explanation than I’m giving right now) but for the moment just keep in mind that it’s one more variable when to consider when choosing the perfect exposure.
Last but not least is ISO. On your digital camera this variable may be controlled way down in the depths of your menu.. somewhere you’d never look… or it may be easy to get to. It depends on your specific model. Check with your manual if you’re not sure. ISO is the digital equivalent of film speed from the olden days. You used to have to choose how fast your film was and shoot an entire roll of the same speed. Lucky us digital shooters we can change our ISO every shot if we want. The ISO controls how sensitive your camera is to light. The higher the ISO number the more sensitive it will be, so a picture shot outside may be shot at ISO 100, but once you go inside you may need to bump it up to more like 800. This will allow you to keep your same settings (shutter speed and f-stop) for a shot without it being much to dim due to the reduced light situation indoors. This is one setting you most likely cannot change while in “green square” auto mode on your camera. But we don’t want you using that anyways 🙂
Ok are you worn out yet? I’m worn out just from typing so I can’t imagine how you must be feeling after reading all this. My suggestion is to just try to master one of these variables at a time by playing with your camera’s AV and TV settings. AV is “aperture value” and allows you to choose your aperture while the camera will pick the right shutter speed for a good exposure. TV is “time value” and will allow you to choose your shutter speed while the camera chooses an appropriate aperture. Both are great tools for the beginning photographer while you learn how to set exposure. Once you’re good and practiced with these settings we’ll get into a little bit more detail about each of the variables and how you can use them to your advantage.
And just because I hate to have you read all of this text without at least one photo, here’s a favorite of my little ones. I’m going to try to put up new photos with each post and give you some the exposure info so you can get an idea of how each of them was shot. This was at 1/125th, f 2.8, ISO 1600 in natural light:
6 thoughts on “How your camera works…”
Awe–some. Very cool, thank you!
Thank you for this site!! Fabulous! 🙂
Thank you SO much for this blog! I have a fancy camera because I do research in computer vision and I needed something with all the settings, only problem? I don’t really know how to set any of them, so I have been using the auto mode! Which should be outlawed for someone with a DSLR!!! Anyways, thank you SO much for starting this blog!!! I read about all these things in computational photography lit, so now I will actually know how /what to change!!!
Glad I stumbled upon your blog. You did a great job at explaining all the stuff someone would need to know.
I’m sure you plan to do this, but if you have any good book recommendations to read when you are first starting out with photography that would be really helpful
Thank you for your tips- really helps me remember all the details from my high school photo 101, about 20 years ago!
I refer back to your blog all the time, but hadn’t looked at this particular post in a while. I’m glad I did. I think the new lens my DH ordered for me should help with the lighting issues I was complaining about on my blog. I went with the thrifty Canon 50mm/1.8. Can’t wait to get it. Love your blog!