UNDERSTANDING THE BASICS OF PHOTOGRAPHY
Listen, this isn't going to be your ordinary 100% accurate technical guide mumbo jumbo, so leave if things get too weird for ya.
Also... it's a work in progress.
I just cut the crap and give it to you in an (hopefully) understandable and fun way.
Ok, first lets get some things out of the way, so we all know what we're talking about here.
What is a camera?
Well, simply put: a camera is a capturing device that converts light into data. It's not a magic box that just does whatever. It is important to realize that the main concept is 'working with light' here. Once you've got that down, you can start to make it work to your advantage.
Where does light come from again?
Well, usually you're capturing reflected light. If you're taking a portrait of someone, most likely they aren't just radiating light themselves. You either have a natural light source, already around us, such as the sun or moon, shining down on them, or they're reflecting articifial light that comes from lightbulbs or the likes.
And then what?
Well, just about everything reflects light, not just your subject, so basicly we've got all this availlable light around us coming at us from all angles. What we can do next is point a camera at a portion of it we find interesting enough and then we're going to isolate that for capturing. We do that by channeling the light through a lens.
So, what does a lens really do?
Well, for now, all we need to know about a lens is that is that it consists of glass elements that control and prepare light for delivery to the camera's sensor. We have to be aware that light travelling through the glass elements of a lens loses some of its intensity in the process. So the total output (from the rear element being relayed to the sensor) will always be less than the total input (availlable light initially hitting the front element of the lens). Depending on the design of the lens, the loss of light will vary. Zoom lenses consist of pretty complex arrangements of moving glass elements (or 'optics'), this usually translates to a greater loss of light than seen with prime lenses (a prime lens is a zoomless lens, a lens with a fixed focal lenght). Built into the lens we've got a little helper to really gain control of the amount of light we are going to give off to the sensor; it is the 'aperture'. An aperture is an arrangement of small blades (known as 'aperture blades') that slide over eachother to form a kind of round shaped gap. This gap, or gate, can be used control light. By arranging the aperture blades to form a smaller gap, less light is being let through to the sensor, which helps us getting a correct exposure. The aperture is also good for controlling depth of field, but we'll talk about that later. For the time let's consider the aperture to be the first line of defense against light (not that we always fight it and can not embrace it!).
Ok, that's cool. So now we've got a bunch of light, we put it through a lens and then what?
Well, like we said, we have to actually capture it. We have a sensor that does that. But before light is going to hit the sensor, it first needs to pass the shutter. The shutter is another tool for us to control the amount of light given off to the sensor. Basicly it blocks all light unless you tell it otherwise. It kind of works like your curtains at home. The left and right curtain held together will block light, now pull both to their respective side and you allow light in. Now let's get weird and imagine count Dracula in his castle in Transylvania as being the sensor of your camera. During the day he has his curtains closed, because he can't stand the intensity of the sunlight. But he has been reading the Vampire Monthly magazine, which had an article about vampires suffering from vitamine D insufficiency. It states that vampires can actually live healthier lives if they expose themselves to sunlight ever so shortly without turning into dust straight away. So what he does next is quickly open the curtains, exposing himself just enough to stay healthy and close them in time in order not to vaporize. Now listen, your sensor is not going to vaporize, but if you want your image properly exposed, you might want to block more light from entering. There's another aspect to the shutter, but for the time let's keep it at it being another way of controlling the amount of light passed off to the sensor... the second line of defence.
Wow, that was... eh, confusing almost. Anyways. So, quick recap. We have a light source -> reflected light -> pointing at a small portion of light coming at us -> light hits the lens -> there's some lightloss when travelling through glass elements -> we can use the aperture blades to control the amount of light -> when can also use the shutter to control the amount of light -> are we now finally going to capture the light?
Yes we are! A sensor consists out of many little photosites that are sensitive to light. Consider a sensor as the roof of a house and the photosites as solar panels the roof is covered with. To get the most efficiency out of a single solar panel, it needs to be of considerable size, having a large surface. Size matters!
So lets talk about sensor sizes for a sec. You have probably used a compact camera before. The usual sensor found in a digital compact camera measures 1/2.3 of an inch in diameter. Nowadays though, we have compact cameras with a 1/1.8, 1/1.7, 1 inch or an even bigger sensor inside. Looking at cameras that have a mount that allows for swapping of lenses we find much bigger sensors though. The (micro) 'four thirds sensor', established by Panasonic and Olympus (later adapted by other brands as well), as the name gives away, features a 4/3 (1.33) inch sensor. A step up from that we find the very common sensor format 'APS-C'. There are some slight variations in actual sensorsize within the format. Going up from APS-C we find the 'fullframe sensor' which is based on the 35mm film standard used in cameras shooting rolls of film. We consider this the standard for digital photography as well, it's the reference if you will, which we take as our base for all non-standard sized sensor cameras to relate to. For example, if we want to compare ranges, we express ourselves in a certain focal length measured in milimeters (mm) conformed to a 35mm equivalent. There is a crop factor in play, but we won't worry about that now. We just needed to establish the fact that there are different sized sensors.
Coming back to sensors/photosites and our story about roofs and solar panels... let's say you have a close friend and he builds a house and manages to fit 20 solar panels on the roof. Now, he convinces you to buy some ground nearby to build your own house. You have a bit more to spend, so you build a bigger house, which inherently has a bigger rooftop. You decide to keep the number of solar panels the same and get 20 as well, but you increase their individual size. Now suddenly 1 solar panel is much more efficient, it has more surface to catch light! More or less the same goes for cameras and their sensors. Sensor real estate is very valuable. It separates a serious camera from a compact camera.
Now, if you look at sensors the resolution is rated in megapixels (MP) rather than photosites. Although the sensor is made out of photosites, there are a couple of photosites needed to form a pixel. What is important is how much surface these photosites cover to create one pixel. Just adding more pixels to a sensor doesn't mean that each pixel is doing a better job. It's like trying to share a cookie with 20 people. They'd rather have a slice of a weddingcake than a few crumbs of a cookie. The photosites would start to starve if you give 'em less light to work with. So next time you see someone with a compact camera bragging it has 24MP, think about the the relation to sensor size and the impact on the light gathering ability of the photosites a pixel is made up out of. Less megapixels can actually be a good thing. It might start to get a bit problematic if the megapixel count is too low, because of printwork and web use, so there's somekind of minimum requirement. Most cameras these days boast 16MP or upwards. Let me tell you, 16MP is plenty! Less, like 10 or 12MP is still fine and wins you some light gathering capability, in turn, more, like 36MP perhaps, will get you finer detail and resolution for art galleries and magazine prints, but at the cost of lowlight performance, if you consider keeping the sensorsize the same when comparing these megapixelcounts.
Ok. Hold on. So now we've got sensors with little solar panels or something. Different sensor sizes. Photosites. Megapixels. I thought you said you were going to 'cut the crap'?
Fair point. Well you're lucky I haven't delved into RGB, Bayer filter and low pass filters yet. But ok, you've got a point. Anyways. The sensor actually turns the amount of light we told it to gather (using the availlable light, the aperture and the shutter) into digital signals that can be processed and stored as data. Voilá, there's our photograph! This is how a digital camera works.
But what I'd like to know is: how do you decide how much light is required?
Ah! Yes. Let's now take a look at the relationship between aperture and shutter (although there's actually a secret love triangle going on here, more later!).
APERTURE We briefly touched on the subject before... a lens has a natural loss of light. This loss of light can be given a value with the unit thereof being an f-stop. The higher the number, the greater the loss of light from entering the lens to delivery from the lens to the sensor at the end. We can create additional loss of light by narrowing the gap of the aperture. For example, a lens which at best can give us its natural f/2.8 f-stop, we can close down the aperture of a bit to let's say f/8. We've also learned that we can use the aperture to control our depth of field. Now, normally you'd first want to pick your depth of field. Do you want to create separation between your subject and the background, emphasizing your subject even more, giving it a really nice look? Or would you rather have as much as possible in focus from front to back? If you want to throw the background out of focus (background defocus is also called 'bokeh'), you might want to use your camera in manual or aperture priority mode and set your aperture to its brightest value (for a 50mm f/1.4 lens this would be f/1.4). If you'd rather have a deep focus you might want to increase the f-stop accordingly (for instant using an 11-16mm f/2.8 at f/11). Now... you do not really need to know the physics behind this and why this happens, just know that it behaves like this.
SHUTTER We've also discussed the shutter. It's basicly curtains for your camera which only open to allow the exposure of the sensor when you tell it to and for how long. A longer exposure will result in a brighter image. What you have to consider with long exposures however is motion blur. There are 'dynamic scenes', with motion from the objects around you, such as people walking, cars driving or birds flying by, within the scene. If you have your camera in a fixed setup, at a certain position, facing a certain way, exposing for a dynamic scene, you might run into problems when the exposure is too long. Why? Take for example a car driving through the frame from right to left... If you exposure for 3 seconds and in this 3 seconds the car will enter and exit the frame, the car will not be captured in a fix place in the frame, because for the duration of the exposure it was not in the frame, right in the frame, in the middle of the frame, left in the frame and again not in the frame at all, all at the same time! At the same time you're exposing parts of the frame where the car will be (or was) without the car in front of it. When taking long exposures of a dynamic scene, you'll always end up with weird blurry images of something captured being there and not being there.
There could be an issue with 'static scenes' as well. The scene might be static, but this time around you're not using a fixed setup, you're shooting handheld... however, if you start taking a picture and use a 3 second exposure, you'll be running into the problem called: camera shake! You see, it's very hard to keep a steady hand... or a complete still one. When you start your exposure for 3 seconds and the camera moves, it captures parts of the scene for a moment that through movement will be captured again elsewhere in the frame. This results in blurry images. To avoid camera shake the use of a tripod is recommended. If you can lock down your camera for a fixed setup and you're shooting a static scene, everything will be dandy fine.
If you don't want any blurring happening due to camera shake, you're going to have to increase your shutterspeed (as to shorten the exposure). A rule of thumb is to take your 35mm equivalent focal length (let's define it as 'x') you're shooting with and use it as denominator in '1/x sec'. E.g. I'm taking a photo with a 70-200mm f/4 on a fullframe camera (already 35mm). At 200mm I'd want to use something like 1/200th of a second or faster to near the freezing motion, or at 70mm -> 1/70th of a second. As there's no 1/70s availlable for selection, use the first next: 1/100 sec or faster.
I keep on hearing people go on about ISO though, what's that all about then?
Well, before I kinda hinted there was somewhat of a love triangle in play here. In fact there are three more things you can use to influence you exposure other than just the aperture and shutter. Two basic ones are obviously adding light to a scene. If your scene isn't properly lit for the picture you want to take, see if you can add light. Lighting is a subject on its own, you should definitly read into it, there are tons of ways to add light, from a simple reflector, reflecting availlable light, to portable LED panels or wired lighting kits. Of course there's the on-camera flash and external flashguns for your hotshoe, but mind you, these aren't really intended to light a whole scene. Flashguns need to be used sensibly. There's an enormous amount you can find out on the subject of lighting, so do read up on it. Anyways. So, that's one additional thing you can do, add light. That's an external factor. Let's take it a little closer to the camera with the next way off controling light: Neutral Density (also referred to as 'ND' for short) filters. Imagine a bright sunny day. You decided to go for somewhat of shallow depth of field at f/2.8 on your 50mm lens. There's sunlight everywhere, so you don't need to light the scene, actually everything is too bright. You're stuck shooting at your camera's fastest shutterspeed which may just be 1/4000th of a second. But in the brightest of conditions (perhaps you're skiing in the mountains, white snow is reflecting bright light everywhere) this might not cut it. Well, do what you do with your eyes if things get too bright... put on some sunglasses! These ND's we talked about are actually sunglasses for your lens. Your lens has a threaded mount on the front of the barrel and an ND filter has threads that allow you to screw the filter onto the lens. ND filters come in various densities/strengths to cater for various situations. There are also variable ND filters of which you can change the intensity by having a rotating element to the filter. This is based on a polarization method and has some side effects, but again, we are first trying to cover the basics here, so ND filters = sunglasses for your lens.
Eh, ok, I get all that, but I thought you were going to explain me about ISO?
Yes, we'll get to that now. First we had to get out of the way all the other things that influence the exposure. You see. We start with availlable light. Then we can add light if we deem availlable light is not enough. We then actually have the option of putting sunglasses in front of the lens, controlling the intensity of light before it hits the first lens optics. Then the light travels through the glass, losing a little intensity. Can then be cut down even more by the aperture. Goes through the shutter and then onto the sensor. Here is where ISO comes into play. It's the last thing we can use to get our exposure under control. What does ISO do? Well, the sensor converts light into signals and with ISO we can amplify these signals. So, imagine you're in a dimly lit enviroment (for some reason you can't add light to the whole scene and ND filters are of no use here) and with your desired f-stop and shutterspeed the light metering of your camera says the shot will be under exposed and liveview shows a rather dark image. You can bump the signal by increasing the ISO. For example, perhaps you were shooting at ISO200 and were underexposing. You can up the ISO to let's say ISO800 or ISO1600 and amplify the signal from the sensor to get a brighter scene, without changing any other settings or enviromental conditions. This is a pretty powerful tool! And as all things that sound too good to be true, this one has a downside as well. You can only take signal amplification so far. Think of it the same as audio amplification. If you turn up speakers really really loud you will probably here some hissing, noise and distortion. The same applies to ISO increments. You will get away with quite a bit of amplification, but at some point you will introduce visible noise to your images. The more basic cameras are usually well capable of keeping very acceptables levels of noise at ISO800 and ISO1600. For the most part it starts to get tricky around ISO3200 and ISO6400. Nowadays we see cameras even taking it up a notch and allow you to select an ISO of ISO12800 or even higher (ISO25600, ISO51200 and believe it or not even ISO409600). Being able to select it, doesn't mean it will have great image quality and will be free of noise, mind you. So generally speaking you'll probably want to keep the ISO value as low as you can. Of course taking a noisy picture might be better than taking an underexposed picture, or perhaps even non at all! ISO performance is different from one camera to the next. But a lot can be appointed to sensor size. When your signal is based on a tiny photosite, there's not much to work with. When the signal comes from a large photosite, the signal is a lot more usable to begin with. That's why large sensors and low megapixelcounts help with ISO performance and lower noise levels at high ISO's.
So there you go. In-camera settings. Love triangle. Aperture. Shutterspeed. ISO.
WORK IN PROGRESS. CONTENT WILL BE ADDED. EVENTUALLY...
