Understand Camera Exposure and start shooting manually

In this online free photography lesson, we will cover a lot of basics, the basic knowledge that you need to take amazing photos, we will learn things like Exposure, aperture, ISO, shutter speed…
You might talk briefly about this subjects in the previous lesson, but you still can't understand it properly, and that's why you are here in Photography 101 course because we will explain it fully so that you understand.

We will be talking about focus, making sure that you know how to get things in focus, but also using focus creatively to get amazing shots. We’ll be talking about using your camera’s light meter to get proper exposure. We’ll also be covering some situations like shooting a fast object, shooting in low light, and even shooting at night.

So we will cover some really interesting topics that I hope you’re excited about.

I. What is exactly Camera Exposure?

This Lesson is about dropping the auto setting and switching to manual, so the most key factor of this is to learn about Exposure.

So what the camera’s doing is taking an image (Taking light that is reflecting off of everything out there) and controlling how much light comes in and hits your sensor, so there are two factors for this :

1. How much light is hitting your subject (human face, car…)
2. How much light is entering the camera

Exposure is about understanding how much of this light enter your DSLR Camera, and how to control it to make it exposed correctly.

So, Basically, exposure is controlling how much light is hitting your sensor, how bright is your image, how contrasting is your image, for that there are 3 tools that control how much light enters and hits your sensor, which are the F-Stop, shutter speed, and ISO.

1. Understand Aperture F-stop or iris):

From Wikipedia : (( In optics, the f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) of an optical system is the ratio of the lens's focal length to the diameter of the entrance pupil. It is a dimensionless number that is a quantitative measure of lens speed, and an important concept in photography. The number is commonly notated using a hooked f, i.e. f/N, where N is the f-number. ))

The first step in controlling exposure is through your lens, and the only thing that controls the light that comes in in your lens is the iris known as f-stop or aperture.

What does the f-stop do?

It allows you to close down to reduce the amount of light coming through your lens; Now it has a lot of different factors, many different lens makers have different techniques for doing this.

Most lenses on the front you’ll have a number that has « 1 »«: » « number » (ex : 1 :2.8) that the last number is the fastest or the most open that the lens can go ; typically this numbers go from .7,1,1.4,2,2.8,4,5.6,8,11,16,22 each number is correlated with a way of reading light, and with each number you are effectively cutting the light in the half., so you reducing the amount of light coming in.

GOING FROM f1.4 to f2 : HALF OF THE LIGHT ENTER THE CAMERA

It is a little confusing because some people will say « Oh let’s Stop down » and then you are going to a higher number, but really what you are saying is reducing the amount of light coming into your lens by up the number which means more cutting the light into the half.

The easiest way to think of an iris is to think about your own eyes, actually, the pupil is one of the most incredible lenses in the world, if you go outside and look into a friend’s eyes, you can see that their pupils will be very small. You going inside to a dark room, and the pupil will begin to open allowing more light in, allowing to see better in that dark.

The camera lenses are very similar to your eyes, where you are able to reduce the amount of light coming in ; there are many other factors that come into getting a good exposure, so through our Pupil, you have the brain, one of the most sophisticated things, and for a camera, there is a lot more that goes into getting that right exposure.

The key element to your iris (f-stop) is that as you open up (have that lower number f-1) your depth of field DOF gets much less, incredibly shallow and you will be able to shoot in a very dark situation ; On the flip side if you go down to f-16, your DOF will become much greater and this is really where the f-stop affects your images, it says how much is going to be in focus and how difficult is it going for you to get what you want to be in focus

We will see in the next lessons from photography 101 course how focus affects your images, how do you control that, and what are other factors when getting things in focus.

 There is a reason that people say it’s all about the glass. This is the first thing that light travel through and ultimately gives you the look that your cameras are going be seeing.

Aperture Charts :

In the day, you have a lot of light, so you should choose the top-left, while if you shoot in a dark room, the bottom-right will be your choice, to allow more light to come into the lens.

The small is the number for f-stop, the large the hole will be, some cameras can’t go bellow f-4 while others can go from f-1 to f-126

2. Understand the camera Shutter Speed

In the section above we talked about the iris and how that controls how much light comes through the lens. And the next step that light interacts with is the shutter, and what the shutter does, it allows light to actually hit the sensor (or film), because as you looking through your viewfinder, you’re seeing the light coming through the lens, and how much light there is but it is the shutter that says how long that light will hit your sensor (or film) and expose to the image.

Slower shutter means more light

1-second exposure (Slow) vs 1/4000th (very quick)

You might hear the term of « shutter speed » and what is mean, is how quickly the shutter is actually moving, so if you’re shooting at 1/8th a second that pretty fast for human, but in term of the camera that actually really slow, and if you holding the camera by your hand, without using a camera tripod, you might not get a clear image, on the other hand it is more typical to shoot closer to 1/250th of a second and 1/4000th.

Shooting at 1/8th shutter speed is allowing more light in, it’s allowing your picture to be brighter, as opposed to a 1/4000th shutter speed where it’s a really quick shutter and you’re not allowing as much light in.

The Other factor whit this though is that as you slow down your shutter, it’s possible that you’ll start to get blurry images. Typically if you’re handheld, going under 1/60th of second, your hand it’s hard to keep it steady and you’ll start to get blurred images at 1/30th or below that even. 

Depend on your situation, and how much light there is, you change your shutter speed ; You decide « Oh well I want to shoot out a f/4 because there is a lot of light outside » or maybe you don’t have any light so you make your shutter move a little bit slower, allowing more light in ; So it’s really important that you test, take a few practice shot and see what you’re capable of doing. Personally i like shooting at 1/100th. I think that’s really safe, even if something’s moving quickly it will be crisp and clean and not blurry.  But sometimes you’re in a low light situation, you need that to stabilize your camera and get a shot that’s not too blurry.

This isn’t say that you shouldn’t use slow shutter speeds, There’s a lot of ways that you can use it creatively and actually get some really cool effects with it ; one of my favorites is seeing the car light at night where you have those long street of light moving across a freeway, and this is all done with a slow shutter speed, but ultimately you have to test, you have to see what /30th looks like and what does a 1s exposure look like, what is 30s looks like, and this is the best way to go and see it by your self.

3. Understand the Camera ISO

After we understand iris and shutter speed, the final aspect of exposure is the ISO or what they use to call ASA.

The ISO has changed over the years though and what it was once into FILMs has in a way translated into digital but slightly different now, so the ISO becomes a rating system to say how sensitive a piece of film was.

Back in the day, the film was made of crystals and they were actually reacting to the light chemically and you go through the whole process of exposing that image in the darkroom, and securing that image into the film.

Now 100 ISO means that the film had very fine crystals, that you’d have a very clean image but it would also require much more light to expose that image. On the other side, 1600 speed ISO means that you have much larger crystals and that you could take photos of the much darker situation, but you had also a much grainier image.

Today, we have the ISO principle in digital photography, but it’s all created from a computer, it’s all ones and zeros and you get certain looks that you could only get with a film that you don’t get in digital nowadays. SO today in modern photography (digital photography) we still use ISO rating system; It's the same numbers, 100 ISO means It will be less sensitive and require more light, and 1600 ISO means It will be more sensitive and you won’t need as much light.

The really exciting thing about today though is that the Digital SLR cameras are getting much more sensative, and you’re able to shoot at 3200, 6400 (one camera shooting 400 000 ISO) and getting a fairly clean image ; Some cameras can see better than our eyes at night, so as you increase your ISO in the digital age, you still have to worry about that grain the same as you did in film, but slightly different today because it’s a cmputer reproducing an image that isnt actually there, whereas the crystals were reacting to actual light.

This is all depending on the camera you using and how it reads light, how it reads grain, and how it reproduces grain, and ultimately the only thing that I can tell you to do is go test to know what is your camera capable of doing; Some cameras at 6400 and still looks greats, and you’ll have a nice clean image, others 6400 will look like red, green and blue dots.

Another factor is the sensor size, and how sensitive can your camera actually get, because although the ISO rating’s always the same, a Full frame camera has a wide sensor compared to an APS-C type or 1.0 type,  so the sensitivities going to have a radically different.

The full frame sensors allows you to have more light coming in into your camera and a greater area for that light to expose on ; When you look to an iPhone for example, you have a very tiny sensor there, and you can get a pretty incredible images, but the ultimate downfall is when you go into night time and it’s really hard for the camera to see at night.

A professional camera like the Nikon d800 has such a large sensor that you’re able to see in the very low light situation.

Always remember : That the Iris and shutter speed affect how much light comes in, while your ISO rating is going to ultimately affect how sensitive is your camera; the best thing you can do is go practice and see what your camera is capable of, what ISO rating do you prefer, and what is ok to sacrifice, when is grain okay ? and how sensitive are you willing to go.

II. Exposure triangle, what is it and how does it work?

Now hopefully you understand what is exposure, and what is the iris and what is the shutter speed, and what is the ISO ; So the real skilled photographers take all three  of those and put them together, some people call this the EXPOSURE TRIANGLE, the 3 main elements that affect how you’re going to expose your image.

ISO- how much light do you have?

SHUTTER – How fast is your subject?

APERTURE – How much DOF do you want?

When it comes to exposure, there’s no set rule on what you’re supposed to do. This is really something that you as a photographer gets to decide, like what f-stop do you prefer, what shutter speed, what ISO. And depending on the situation, you’ll find yourself preferring a certain look to another, 

A. Bright situation:

I personally think it’s easiest to say « Oh well it’s kind of bright outside so I’m going to shoot at ISO 100, because I know I’ll have enough light for that » And then I’ll decide « well I want to shoot at f/4 and from there whatever the shutter needs to be, I’ll adjust accordingly ».

B. Low light situation:

Let’s say I shoot in a dark room and i said « Oh man, i need all the light i can get » so I will take it to the highest ISO that I’m comfortable shooting at, let’s say ISO 1600 and then I’ll go down to a 1/60th shutter speed, because that’s the point where I know I can be handheld and not get too much blur, and it'll open the f-stop to where it needs to be. And dependent on what my image looks like, i will take the shot, look at it, and if i need more light, i open the f-stop a little bit more, or i make the ISO a little bit more sensitive.

The game is to practice, take shots, and then import that images into computers, and look at them on the computer screen and see what you are able to improve.

When it comes time to shoot you really need to think about this 3 factors, and sometimes it is safe to say « forget your ISO and focus on aperture and shutter speed » or try to take a shot at ISO 100, 200, 400, …2000 And then later look at them and see how they look alike, what the different ? and decide what you like; then start shooting at every f-stop and so on.

The best thing you can do with digital photography is taking thousands of photo, just practice, practice, practice and see what your eye likes, and found that exposure that it is right for you.

III. Camera light meter, what is it? and how to properly use it

The final tool in getting your photo exposed correctly and getting in focus is your light meter, and this is actually a great tool that a  lot of film cameras would use because it’s a way to letting you know when is your photo exposed correctly; And you can do this without ever taking a photo, because back in the day in film you don’t want to take 10 shots, you could only take that one shot, and the light meter was a very important tool to make sure that you are exposed.

Where can I found the light meter?

In Some cameras you can look at the light meter from the top, and there will be a middle mark then a +1, +2 ,+3 to the right and then a -1, -2, -3 to the left; Other cameras you have to look through the viewfinder to see that, and some other you can actually see it on the back screen.

How light meter works?

The way that the light meter works is that it’s basically telling you how overexposed (too much f-stop) or how underexposed your image is. And simply by looking at it, you can know if you need to make your shutter speed faster or I need to open up my f-stop.

Although the light meter will tell you when your images are in the middle, when it’s properly exposed, that’s not to say sometimes you don’t want it to be overexposed or underexposed.

Sometimes when taking a photo of landscape you’ll have some buildings or something that’s really deep in the shadows and it might be telling you it’s underexposed, that’s too bright, but then you go and take a photo and your sky looks great but there are other areas of the image that are really dark. And that’s not a bad thing, that’s your creative choice.

As always, go and test, see what it looks like when it’s bright in the middle. Maybe overexposed, see what that looks like, try underexposing ; light meter is a really useful tool and as you get to know your camera better you’ll be able to know what will give a better result, so choose one subject lets say a three and take a photo of it when you are -1, -2 and +3 and compare those results to see how the overexpose, underexpose effect the image and different part from the subject.

IV. Camera Histogram, What is it? and how to use it like a pro

What’s a histogram and how to use it in photography, this article will show you exactly what is a histogram and how to read it, and how it can improve your photography skills?

Histogram Definition :

Histogram is a graph that visiually represents how dark or bright your photo is, and does it go from dark to bright, From the photo above, we see that in the left its pure black, and in the right it’s pure white, and in the middle are your midtone, so you’re grays and your neutral colors and tones that aren’t too bright, and aren’t too dark ; also every pixel in your image is representing in this graph, so if there is alot of darkness in your photo (underexpose), the pure black area in histogram will be really high, in the otherhand if there is a lot of white (overexpose) in your photo, there will be a peak in the right side of the histogram.

In the histogram above, we can tell without even see the photo that it is very contrast, meaning that there is a lot of darks and a lot of bright colors, and not so many mid-tones, but it is a very well expose photo, because the dark pike don’t touch the left side of the histogram, same for the white pike.

Example of a bad exposed image histogram :

Above you can see the histogram of 3 different pictures

1. Overexposed: There is a giant hill with a giant peak at the right, touching the right side, which means that there are many white pixels in your image.
2. Underexposed: A lot of pixel on the left side, and no so many in the middle or on the right.
3. Normal: the normal histogram reading shows that there is a lot of mid-tones, and nothing is completely overblown or nothing completely black. 

A well balanced and a well-exposed photo will have pixels across the entire spectrum like the « normal histogram » where some touching the right, some touching the left, but then the majority in the middle, and of course this has to do with your artistry as well, maybe you want that dark in the left or that bright in the right.

the histogram allows you to see visually what is bieng exposed and how its beeing exposed.

How to read histogram in a digital camera?

1.    Hit « START STOP » button (it won’t work if you are in the video mode, make sure you are in the photo mode)

2.    Hit « INFO » button until the histogram pops up

When you take a photo, you can also review the photo using the histogram, so you hit the button « review » and you hit the « info » button until you get the histogram for that photo.

Remember to view the histogram when you are taking a photo.

So That's what a histogram is, I hope you learn a lot about it and how to use it, and that you’re now able to use it when you’re out taking photos and I hope that this knowledge helps you to take a better photos, because that's what all this photography lessons about, to help you to better understand and you your camera for taking a better photos.

Go out and practice with using your histogram, if you have any question then put them in the link below.

In the next photography lesson we will be talking about the basics and history of a camera, and how does the camera works and upgraded by time.