This lesson will be a bit longer but if you understand this section it will make photography and film making so much easier to understand and start trying things out. The reason exposure is the most important thing to know is that it is basically the key element to photography. The word photo itself comes from Greek meaning light. Graph comes from the Greek also and it means to write down or sketch. So the definition of photography is to put down light onto paper. So in order to take great photographs you have to think in terms of light. It’s great if you have something to cool to photograph but without the right light or light manipulation good luck getting a great photo.
Now you might be thinking well the camera is digital and has a lot of settings. I’ll just crank them up and it will develop. Well yes but there is a catch. In this lesson we will go over three main ways, and one bonus, to help but also the trade offs of each and how to use them to your own advantage.
ISO
ISO or international standards organization for short is one way to change the exposure of a photo. Now I know some people might wonder why I would start with this one. The answer is simply because when you try taking a picture on your phone you might notice an “exposure” option. But what you are really doing on any other camera is changing the ISO if the image.
The fact you can change ISO between each photo is a miracle in modern technology. Before digital photography ISO was actually telling the photographer just how light sensitive the film was they were using. So once you added a roll of film to the camera it was a much more firm decision. If you wanted to change ISO on the fly you’d have to either use up the whole roll or decide you were just going to waste the rest of the potential photos on the roll.
Yet just like film the digital and film ISO have very similar trade offs. The lower the ISO the clearer the image but darker it is as well. Where high ISO provides more light exposure but it is not as sharp. In film stripes it would cause the grainy look but in digital film it creates “noise.” Pixel Resolution also plays a factor in noise but that will be for another lesson. So unless you are going for a certain kind of distorted feel ideally you’d want as low of an ISO you can but not to low where things are too dark. So how do you manage that? Well you still have other methods to correct this if you are using a digital camera and not most cell phones (at the time of writing this anyway.)
Film Speed
Right off the bat I want to mention that some people might confuse film speed and frame rate when talking about videos. I will break down the frame rate a lot more in future lessons. Simply put however is frame rate is how many pictures are taking an a time period and film speed is the duration the picture is taking. Ignore frame rate for the rest of this lesson as we focus on speed.
So what does it mean how long the picture is taken? Simply put once you hit the shutter or press the button on the phone there is a finite amount of time that does transpires from the pressing down the button to the picture being taken. Most beginners using a phone might have only noticed this when taking a photo on their phone without a flash and noticed they had to hold the phone still. But why is the length so important? Well let’s think in terms of a film camera again.
If you have ever seen photo paper or film paper you know just how sensitive to light it is. Or if you are a dumb kid like me you might wonder why your sister has a brown bag in the fridge that says “do not open!” Followed by more warnings as you open that and finally a box. Only then to open it and see a bunch of glossy paper turn black to white in a few seconds. Then your sister finding out and kicking your butt. Ok maybe that is more close to home for me. But as I personally say as soon as I opened the box it turned white before I even had time to process what I was looking at. That’s why pictures are taken so quickly in most cases. Also that’s why the button that takes photos is called the shutter release. The film sits behind the lens but behind the shutter until you open it letting in the light until it shuts again.
Now if you have used a film or digital camera (we will ignore phones for now). You might have noticed numbers in possibly the hundreds or thousands if you have taken photos in a manual mode rather than an automatic. This is typically the film speed being displayed. Also it’s important to not that those big numbers are actually fractions (I know math, yay! <sarcasm>). So when you read for instances 4000 it’s really 1/4000 or 120 is really 1/120. And that’s actually of a second. Which is pretty fast. But what does that have to do with exposure? It’s very simple the longer the more time means more light where less time means less light.
So what’s the catch? Just like everything dealing with exposure there is a trade off. In the case of speed it all boils down to motion blur. So what is motion blur and why is it important? Real quickly I want you to try something. Hold out your hand about a foot from your face and just look at it and notice the details. When you are ready wave you hand very quickly side to side. Notice how when you do that even though you know all the details of your hand you can’t see any of them when you move it rapidly. Smaller film speeds there is more of a blur. But if you were to do the same thing but now tried to take a picture of it you could potential get a photograph that comes out clear of your hand. Provided it’s fast enough and well lit.
So how is the trade off helpful? Well if you are taking portraits but don’t have a great light source you can still keep the ISO low by reducing the speed. Or say you are taking pictures at a baseball game. If you have a high speed you could with practice get a photo right when the batter hits the ball and see all the detail in that moment. In fact things like running water could have very fascinating results depending on what you set the film speed.
One final note for photographers. If the camera has a number the reads something like 1’ or 2’; or you see something that reads “B” these are special modes of slow. First 1’ or 2’ is actually 1 whole second or 2 whole seconds. For starters use a tripod before getting a photo this slow. It allows for a lot of light exposure but if the object or the camera moves it will be blurry for sure. Lastly “B” is actually means Bulb. Not all cameras have this but when bulb mode is set as soon as you push done the shutter button it opens and won’t close until your release it. Not in bulb mode a some modern cameras might think you want to take rapid photos but that’s something for another time. The main reason you’d want bulb mode is getting picture at night and you only have natural light. This allows for both pictures of stars but also interesting light streaks from moving images in the dark. Not all modern digital cameras have a bulb mode but I can’t stress enough tripod.
Final notes for film makers and cinematographers. First all the rules are the same but since you are talking about rapid firing of images you can’t have speeds slower than the next frame being filmed. It will be broken down further in frame rates but if you shoot at 24 frames a second. That means you can’t have film speeds slower than 1/24 of a second. If you did than that exposure would cross over into the next frame. If you could hack the camera it may create a ghost image or just crash the system. Not sure as I’m explaining theory not the science. Also to get the most “natural” feel or what you would “see” (remember the moving hand demonstration?) than you want your speed to be twice the frame rate (ignoring it’s actually a fraction). Once again if you are shooting 24 frames a second than ideally you’d want the speed to be 48 (really 1/48). Not all digital cameras give an infinite number of options for speed so rounding to 50 (really 1/50) would be pretty close(0.02 seconds seems pretty small difference to me).
Second off sometimes cameras use shutter angles instead of speed or can be set to that if you prefer. You’ll see numbers between 0 and 360 which happen to be the same as the degrees in a circle. The reason is old cinema film cameras used to have a spinning shutter so as the film moved through the same film speed was applied to each frame by spinning in at a changeable rate. Unfortunately I only know the theory rather than how it breaks down in detail. But here are notes you need if you use degree. The most “natural” look is 180 degrees (180/360 = 1/2 so a frame rate of 24 or 1/24*1/2 = 1/48, hints the double rule). Any number larger will let in more light and more motion blur in the video. Any number lower will need more light and the frames will have more detail.
Aperture
So far thinking in terms of a film camera we have gone over the film itself and how long light hits it. But there is a third way to manipulate the amount of light coming in. You do that by changing the aperture on the lens itself. Let’s start with the theory and then get into the boring technical stuff.
Aperture is simply just how open or closed the hole in the lens is that lets the light in. If the aperture is open very wide then a light of light would come in. But if the opening is very small the image would be darker. For instance if you squint your eyes you will notice you can still see but things are a lot darker. There isn’t as much light hitting your pupils so because your eye lids are blocking it. Fairly straight forward idea.
So of course what is the catch? Well the catch to the aperture size the more open the aperture is the more shallow the depth of field. The depth of field is a range of just how much can be in focus. If you want everything in your shot to be in focus you have to decrease the size of the aperture but then you are also letting less light in. Having things out of focus in the shot isn’t actually a bad thing as long as the main subject in the shot is in focus. In fact sometimes you might use this to draw your attention to the thing in focus.
Side note, when you are photographing a person the best way to know if a person is in focus properly adjust the focus on their eyes. This is done for several reasons, first people are usually more drawn to looking others in the eye. Secondly usually if the eyes are in focus the face will more likely be in focus overall. If an actor is trying to show emotion in a scene but you can’t read their face it’s going to be a lot more work for them. Now there are artistic reasons you’d want to ignore this but eyes are usually a recommendation.
Now comes the more complicated technical stuff. Aperture sizes are in what are called f/stops. Your camera might have an f in front of the number or might just have the number. Unlike speed numbers for f/stops are usually pretty low. Where it may confuse some people is here. The smaller the f/stop, the wider the opening of the lens and the more light gets let in. The larger the f/stop the smaller the opening and the less light gets in. But if you think in terms of focal length it makes more sense. The smaller the f/stop the smaller the focal range is but the larger the f/stop the greater the range is. So f/3.5 would be brighter, more shallow than f/4.
Also one more really technical but important note about aperture and lenses. Sometimes you might hear someone say they have a fast or slow lens. Or sometimes you will see two very similar lenses but the price difference is extremely different. The reason is because not all lenses have the same F/stops. You can actually read the focal length on the lens itself. But a “fast lens” means it actually opens a lot wider than a “slow lens” For instance I have 25mm lens that opens up as wide F/1.7. But I also have a 12mm – 35 mm that at most when set to 25mm opens up to F/2.8. So my 25 mm lens would always be better at letting in more light and getting the most shallow depth of field between the two options. Won’t break down differences in zoom and prime here. However if you are shopping and you see two options for the same length lens the lens with the lower f/stop is usually more expensive. You may not need a lens that opens up as wide but that’s something to consider when creating your kit.
Mastering the balance between speed, aperture, and ISO levels are essential and takes a lot of practice. But it makes any good photo a great photo.
ND/CPL Filters
This last section isn’t important for mastering a camera but will give you a slight edge in bright conditions. In fact I dare say this might be a little bit aimed more towards film makers. So let’s say you are outside and its a bright day. You have your ISO as low as possible, you have a low f/stop because you want the shallow focus. But now your speed is very large number (or technically fraction) So everything is coming out nice and sharp. But you want that shallow depth of field and that hint of motion blur. Your ISO won’t go any lower so what do you do? That’s where filters come in.
A ND filter or Neural Density filter is an extra layer of glass you can screw on to your lens to help reduce light. It is literally the equivalent to putting on sunglasses outside (do not try to take pictures of the sun as you can burn out the sensor making the camera unusable). It reduces the light so now you have more room to play with the speed and aperture of the camera.
Another filter you might see is a CPL or Circular Polarizing/Linear is similar but different. It is still like putting on a pair of sunglasses but this time they are polarized lenses. One thing you might notice with polarized lenses is one it’s harder to read your phone screen, and secondly if you tilt you head the tint changes and random reflections give off an odd shine. You can have the same kind of effect on you camera but unlike sunglasses you won’t need to tilt your head. the filter will actually spin causing the same effect. If you are looking to just darken an image it’s preferred you use just an ND Filter but if you also want to play with reflections on shiny surfaces than A CPL might be a good fit. Below is a video of me turning a CPL filter. Ideally though you’d find the angle you want and just leave it but it has some visual range to it.
Before you buy filters it’s important to know they will fit. When looking at a lens look for the number on the lens with the symbol that looks like a 0 crossed out as seen below. This tells you the diameter of the filter threading. Note not all lenses have threading and if you have multiple lenses not all of them will be threaded the same. Keep an mind filters are 100% optional and not required.
Colt Classic Pictures 