Site Intro

This site is designed to teach the most basic elements of DSLR photography in the most simple way possible with examples to illustrate. The goal of the site is so that photographers new to DSLR photography from either proper point-and-shoot cameras or cell phone cameras are able to begin to maximize what DSLRs are capable of beyond their full-auto and pre-program modes (which are not covered here).

I am a Canon shooter, but you should choose whatever DSLR you use based on your personal preference. I will reference Canon and Nikon specifically as they are the most widely used, but everything here is applicable to every DSLR on the market today (as well as advanced point-and-shoots and mirrorless cameras that allow these adjustments). Please note! As this is not a "How to Use [X] Camera" site, I cannot possibly cover how to change each of the functions below on your particular camera. This site is best used in conjunction with your instruction manual, so that you can see how to make the adjustments below on your own camera.

Please see the labels right above this text to skip to various aspects of DSLR photography such as ISO, Aperture Priority, Etc. I have lettered these labels in the order that I believe they should be covered (although F. and G. could be switched) - so it's best to start with A. and go down the line.

Thanks for reading!


Introduction and Camera Types

Pictured above are seven different cameras.
Across the back left to right: Canon A2e (35mm film), Canon 5D Mark II (full-frame digital), Canon Rebel XTi (1.6x digital), Crown Graphic View Camera (4x5 film)
Across the front left to right: Canon SD 1400 IS (point-and-shoot), Canon G11 ('advanced' point-and-shoot), and GoPro HERO2 HD (sports action camera)

Photography should always be about the end product not the cameras themselves, but nevertheless the camera that you choose to use is important.  I've included the photo above of a variety of cameras to illustrate some of the different sizes and shapes that cameras have and continue to come in: all of these camera types are still available today. 

The oldest camera above - in the far right of the back row - is a view camera which shoots on 4 inch by 5 inch sheets of film: 4x5 is still commonly used in certain professional fields of photography and is readily available.  This type of camera is called a 'direct view' camera, or simply a view camera: this is because the image is viewed directly through the lens via ground glass.  Once you've focused the image on the ground glass through the open shutter, the shutter is closed, a film cartridge is slid in in front of the ground glass, the slide is pulled out from in front of the film, and the shutter is released.  Even small 4x5 cameras are bulky to carry around, but they offer quality unmatched by any other photographic medium (8x10 is also a common size sheet film for view cameras).  As the image is viewed directly through the lens to the ground glass, the image in the ground glass is upside-down and backwards, which takes some getting used to.  4x5 cameras today are only used for subjects that are still: landscapes, product shoots, etc.

The three cameras to the left of the 4x5 in the back row are all SLRs - Single Lens Reflex.  It's called a 'single lens' reflex, because the camera only has one lens.  (Twin Lens Reflex cameras do exist but are not very common today: the top lens is used as the viewfinder, and the lower lens exposes the film/sensor.  The lens is shared on an SLR.)  The 'reflex' in SLR is because you're looking through the camera's lens via a reflex mirror that runs the image through a prism so that we see the image in the viewfinder right side up.  When the shutter of an SLR is fired, the mirror flips up to allow the image to go back to either film or the digital sensor on the camera.  The 'D' in DSLR simply stands for "Digital" SLR: SLRs that use a digital sensor instead of 35mm film.  An SLR's main advantage is its speed: when you press the shutter it fires instantaneously.  Additionally, all modern SLRs have quick auto-focus. 

NOTE: resist the urge to use any sort of 'live view' function when photographing with a DSLR unless you have good reason.  Get into the practice of using the viewfinder as it will allow you to hold the camera much more steadily and shoot quicker.  Shooting a DSLR using the screen in back on a regular basis is like announcing that you're new to DSLRs.

The three cameras in front are all variations on point-and-shoot cameras.  A point-and-shoot camera is a camera with a fixed lens (often a zoom lens: fixed as in not removable from the camera) and very basic adjustments: you pretty much just "point" then "shoot."  Many point and shoots do not have a viewfinder: you simply use the screen on the back to compose your photo.  When you go to hit the shutter there is always a slight delay before the shot is taken, which makes point-and-shoots often less than ideal for anything involving any kind of motion.  Some more advanced point-and-shoots like the G11 pictured above will allow for user control identical to a SLR, but this delay still separates them out from true SLRland. 

Not pictures are mirrorless cameras, which have had a huge rise in popularity lately.  Mirrorless cameras are similar in function and size to point-and-shoots, but they use interchangeable lenses and generally have significantly larger sensors than point-and-shoots.

Why Shoot a DSLR?
Don't bother purchasing a DSLR unless you're really going to take advantage of it.  Even the cameras in iPhones, Android Devices, and the newest BlackBerries take excellent photos which can be blown up to 8x10 or larger with little loss of quality.  If you're into basic, simple, and light, stick with your phone's camera or a point-and-shoot which does most of the work for you.

The following are the reasons to shoot a DSLR:
- Instantaneous shutter response
- Faster autofocus
- Greater creative control
- Greater depth-of-field (selective focus)
- Larger sensors than most point-and-shoots 
- Much better low-light performance
- Nearly unlimted lens options (particularly with Canon and Nikon)
- A must for any sort of action photography, from professional sports to your kid running across the room

Holding a DSLR for the first time may feel intimidating, but relax: they're a lot more simple to use than they might seem and after you learn a handful of basics (the point of this blog) you'll find that you feel much more at ease and that you're able to photograph in ways that you've never been able to before.   

A Word on Autofocus

There are three focusing options on pretty much all DSLRs:

1. Auto Autofocus
2. Manual Autofocus
3. Manual Focus

Number 1 is the AF default: the camera will automatically focus on what it automatically chooses to focus: push down the shutter button halfway to autofocus.  Depending on your camera, it will communicate to you when your photo is in focus: usually by either flashing one of the sensors in your viewfinder, or something similar.  Check your instruction manual if this is not entirely clear to you.

Number 2 is halfway: the camera will automatically focus for you, but you tell it which specific area of the photo that you want to focus on.  For example, on Canon cameras with a 9-point AF system, you tap the AF selection button and then use either the thumb nubbin or the control dial to choose which AF point you'd like to use. Again, this will vary by camera: if you're not sure about yours, check your instruction manual.  If there's no AF sensor near where you want the focus to be once you've composed your photo, no problem: just put one of the sensors over your subject matter, hold the button down halfway to focus on that object, and then while continuing to hold the button down halfway, recompose your photograph.

Number 3 is easy: for entirely manual focus, flip your lens' switch from "AF" (autofocus) to "MF" (manual focus).  Simply turn your lens' focusing ring, and when the subject matter comes into focus in your viewfinder, you're set to go.  Many lenses made now allow you to use your lens in manual focus even when switched onto AF - check your lens' instruction manual before doing this though.

Don't bother with manual focus unless you have good reason: for example, if you're in a low-light situation photographing something still (like a cityscape) and the camera is having a hard time auto-focusing.  Otherwise, default to one of the autofocus settings.


A Word on Flash

Don't get carried away with the use of flash, unless you have a very good reason.  Flash completely alters the look of the light in your photo, and often does more bad than good: especially when you're drawn to the light that you're trying to photograph.  Perhaps oddly, the opposite of one's normal intuition is correct when it comes to flash usage:

- flash for use outdoors in bright sunlight
- no flash for use indoors in low light

Fill Flash
One of the most important uses of flash is fill flash: this is when you use your flash to balance out the available light.  The best example of this (and the most frequent situation that one may photograph in) is when photographing someone in bright sunlight, when the sun is either behind or above the person you're photographing. The two dashing portraits of me below were taken (with my outstretched hand) with a Canon SD 1400 IS point-and-shoot camera, to demonstrate that even the smallest camera's tiniest flash can serve as a fill flash.  Note how in the second shot the bright sunlight is still in the same spot as the first, but the flash lights up my face to balance the shot out.

Using Flash in Low Light
The reason that flash is not always ideal is that to light something correctly is quite complex: a built-in flash has very little functionality at all, and even an external flash has its limitations.  Even the most powerful built-in flash on a DSLR is only really good for about 10 feet or so at the most.  It will work very well for fill flash (above) but not for lighting anything meaningful.

The photos below illustrate three different things.

1. The flash really only is effective for about 3 feet: the only thing it lights up in the photo on the left is the back of the guy's head and some of the white shirt in front of him.  Ultimately, the flash only creates a huge distraction away from the focus of the photo (the stage at Radio City Music Hall).

2.  The flash doesn't change the light in the primary subject (the stage) in this instance, which as with what was stated in #1 renders it useless (and a distraction to the other people who have to deal with the backs of heads being lit up during the show).  In other instances, using the flash will illuminate whatever's immediately in front of the camera, and completely blacken out anything behind it.

3. These two shots were taken with an older Canon SD 780 IS point-and-shoot, illustrating that "my camera isn't good enough" is not a valid excuse.  Whatever camera you have, you can make it work!

This section on flash is short on purpose: as you move through these initial steps of learning DSLR photography, only use flash 1. if you need it for fill flash, or 2. if you have no other choice.  I'll note in sections below when you might want to use your flash - if nothing else is working for the particular subject matter you're photographing.   

An external flash gives you many more options, but these options will not be discussed in this introductory material.

A Word on Light

Light Meters:
All DSLRs have built-in light meters which measure the light that the camera sees through the lens (TTL). Most DSLRs have light meters which can evaluate light in several different ways - please see your instruction manual to see which options your camera has, and for the differences between these settings. Until you get more familiar with your camera leave your light meter set as is.

The main three adjustments that need to be made to the camera are:

1. ISO (adjusts the sensor's sensitivity to light)
2. Shutter Speed (how fast the shutter fires)
3. Aperture (the size of the opening in the lens when the shutter fires)

Each of these have a section devoted to them, but this simple analogy below is nessesary to see how these three settings relate to each other.

Take a look at this simple set of numbers:
(20) 4 + 16

In the ISO/Shutter/Aperture relationship, the (20) above represents the ISO, and the second two numbers represent Shutter Speed + Aperture. Two things are illustrated here:

1. You can choose any first number that you'd like, but that will change the second two numbers
2. The second two numbers work in relationship to each other

To illustrate, all of the following examples work:

(40) 23 + 17
(25) 2 + 23
(10) 7 + 3

Now to put this in photographic terms to illustrate the relationship of these three items. First you pick your ISO, and then a combination of Shutter Speed and Aperture that take into consideration the choosen ISO.

With a DSLR, either aperture or shutter speed can be prioritized. That is, if a certain aperture is more important to you you can change the shutter speed to allow for your preferred aperture (more on why you'd want to do this in the aperture section here). If a certain shutter speed is more important to you, you can change the aperture to allow for your preferred shutter speed (more on why you'd want to do this in the shutter section here).

ISO, Shutter Speed, and Aperture all relate to each other. ISO is chosen first, and then the correct combination of Shutter Speed and Aperture taking the chosen ISO into account.


What it controls:
How sensitive the camera's sensor is to light

What is the range?
Low numbers to high numbers: the higher the number the higher the sensitivity (i.e., the darker the situation a camera can be used in while still having enough light to create an image)

Important issue:
The higher the ISO number used, the 'grainier' the photo looks (that 'grain' is called 'noise'). Below are details from two photos where you can see a comparison of a low ISO (50) on the left, and high ISO (25,600) on the right. Note particularly the blurry green section of both photos: in the ISO 50 photo the green is smooth: in the ISO 25,600 photo the green is noisy. To repeat: the higher the ISO, the noiser the photo.

     ISO 50                                                                                                            ISO 25,600

For those of you who remember film, digital ISO is the exact same thing as film ISO, which comes most commonly in speeds of 100 or 400. Probably the number one advantage of digital over film is the high degree of sensitivity to light that digital is capable of while still looking good: how a camera can handle high ISOs is far more important than megapixels (every camera available today has more than enough megapixels). To change the ISO on your camera, look for either a button or menu that says 'ISO' - if you're not sure where it is, check your instruction manual.

Basic rules:
- Always set your camera to the lowest possible ISO for the light you have (for a better quality image with less noise)
- The more light you have to work with, the lower the ISO you can set your camera to. Conversly, with less light you need a higher ISO
- The higher you set the ISO the lower the quality of the image

In practice:
This is the first thing that needs to be set on your camera before you shoot, and this is based on how much available light you have. ***NOTE: human eyes' ability to see in low light far exceeds what cameras can see. Even a room which seems relatively bright to us can be pitch black to a camera: keep this in mind as it will make how your camera acts make more sense.***

If your camera has an AUTO ISO feature, feel free to use it. AUTO ISO will change the ISO automatically based on how much light you have as measured by your camera's light meter (which was discussed in the 'Light' section above). Pay attention to what it's doing though, so that you start to see what the camera chooses under different light. There will come a point where you'll want to know how to judge this on your own, and there are times that you'll disagree with what your camera wants to use.

If you don't have AUTO ISO on your camera, don't worry about it - here's how to figure out where to set it. Think in terms of ISO 50-200 being used in bright sunlight outdoors, ISO 400-800 being used in cloudy weather or indoors with relatively bright lighting, and ISO 1600+ being used in any low-lighting situations. The best way to learn is to experiment: see what the different ISO settings look like on your camera. As long as you're satisfied with the image quality that you're getting, don't hesitate to use a higher ISO.

NOTE: If you're using a tripod and are shooting something still (landscape, cityscape, still life, etc.) then you can use as low an ISO as you'd like - this will simply affect your exposure time. 

ALSO NOTE: If you're trying to freeze motion in lower light, a tripod is of no help to you as you'll still have to use a higher ISO in order to freeze the action.

Program Mode (P)

What you control:
1. Making the exposure lighter or darker
2. Flash or no flash (on cameras with a built-in flash)

What is the range?
1. For exposure: Either -3 to 3 or -2 to 2 depending on the camera. The lower the number, the darker the exposure. The higher the number, the lighter the exposure
2. Either the flash is turned on or off

Program mode is one step beyond full AUTO mode (the green box on Canon cameras): the camera is still controlling the shutter speed and the aperture, but you'll tell the camera if you'd like the image darker or lighter than the exposure you just took. This is a matter of personal preference.

                         -3 (-2) - - - - - - - - - - - - - - - - - - - - - - - - - - - 0 - - - - - - - - - - - - - - - - - - - - - - - - - - (+2) +3

How to use P mode:
Choose your ISO
- Turn the control knob to 'P'
- Take the photo that you'd like to take
- Review it on your camera's LCD
- If the image is too light, lower the exposure compensation (lower numbers) (Check your camera's manual to see how to do this on your camera)
- If the image is too dark, raise the exposure compensation (higher numbers)

- Additionally, if your camera has a built in flash you can decide if you'd like to use it or not. More is said below about flash here, but for the moment always default to no flash indoors, and flash outdoors: this might seem a bit counter-intuitive but it's explained in more detail below. If you don't like how the photo looks, try the opposite of what you just tried flash-wise.

Learning photography is all about experimenting around: there's not really a "right" way or a "wrong" way to photograph. The point is learning the functions of the camera so that you can get it to do what you want it to do - whatever the style or look that you're going for. In the example above, I would prefer something between 0 and 2: for a different photo I might have a completely different preference.

- "My photos are coming out blurry!" You probably don't have enough light for the ISO that you're using. Either switch over to using a flash (assuming that you're not) or choose a higher ISO (for more on flash see above). Even on AUTO ISO cameras have an upper limit that might come below your camera's actual ISO limit on the high end. If this is the case, either allow your camera's AUTO ISO to go to higher ISOs, or choose a higher ISO manually

Shutter Priority Mode (Tv, S)

What you control:
1. How fast the shutter fires
2. Making the image lighter or darker

What is the range?
Usually from B (bulb - as long as the shutter button is held down the shutter stays open) through either 1/4000 or a second or 1/8000 of a second, depending on the camera. The smaller the number, the quicker the shutter speed

Shutter Priority Mode ('Tv' on Canon, 'S' on Nikon) allows you to prioritize your preferred shutter speed depending on what you're trying to capture. Faster shutter speeds can freeze action, and slower shutter speeds can show action. Below is an example of a fast shutter speed (1/200th of a second) and of a slow shutter speed (26 seconds). Even though I'm juggling four juggling balls quickly, a 1/200th of a second shutter speed has no problem 'freezing' this action. In the photo on the right, I'm juggling three lighted juggling balls in a dark room: because of the long shutter speed, you can see 26 seconds worth of juggling in one exposure. Additionally, longer exposures allow you to photograph night scenes where freezing action isn't necessary. For other examples of what you can do with a long exposure, look here, here, here, or here.

         1/200th of a second exposure                                                                    26 second exposure

How to use Shutter Priority
- Choose your ISO
- Turn the control knob to 'Tv' or 'S' (or other, depending on your camera brand)
- Choose your shutter speed (generally this is done with your main control dial)
- The camera will then choose the correct aperture setting to match your shutter speed.
- Take the photo that you'd like to take
- Review it on your camera's LCD (zoom into the image to check focus (check your user manual to see how to do this))
- If you don't like what you see, re-adjust your shutter speed
- As with the P mode, you can change the exposure compensation to lighter or darker (the camera will NOT change your Shutter Speed when in Tv (S) mode: it will adjust your aperture)
- Note: if using flash, check your manual to see what your camera's highest flash sync is. Most cameras max out at either 1/200th or 1/250th of a second, which means that at speeds higher than this you can't use your flash

"My photos are coming out too dark!" If you're still having this problem after changing the exposure compensation, you're probably using too fast of a shutter speed for the amount of light that you have available to you. Either use a slower shutter speed or turn up your ISO to a higher number, or you can try using a flash.

Aperture Priority Mode (Av, A)

What you control:
1. How much of the image is in focus
2. Making the image lighter or darker

What is the range?
- This depends on the lens, and is measured in f-stops (say the 'f' - "eff-stops") also called 'f-numbers'. This can start as low as f0.95, or f1.2 (you'll pay for that privilege), but the most common lowest f stop on a lens purchased with a camera is f3.5.
- Most lenses regardless of their lowest f-stop will go up through either f22 or f32.

- The lower a lens' f number can go, the 'faster' the lens is considered.
- Anything below f2 is considered 'fast.'
- On most (but not all) zoom lenses, the greater you zoom in the higher the base f-stop becomes. For example, you might have it set to f3.5 when you're at 18mm, but when you zoom to 55mm the camera will read f5.6 even though you didn't change the f-stop.
Aperture Priority mode ('Av' on Canon and 'A' on Nikon) allows you to prioritize your aperture setting on your camera, which allows you to control how much of the image that you're taking is in focus. (Aside: the aperture is regulated by a set of 'blades' in the middle of the lens which you will generally not see, but don't worry, they're there.) 

***Critical to know***
The lower the f number, the less there will be in focus in the photo: the higher the number the more that will be in focus in the photo.

***Also Critical to know***
The lower the f number, the less there will be in focus in the photo: the higher the number the more that will be in focus in the photo.
(This is a repeat of what I have under "Critical to know" because no one pays attention on the first read)

In the chart below, notice how everything on the left side of the diagram lines up (low f-number, big opening, little in focus) and the whole right side of the diagram lines up (high f-number, small opening, more in focus).

How to use Aperture Priority
Choose your ISO
- Turn the control knob to 'Av' or 'S' (or other, depending on your camera brand)
- Choose your aperture (generally this is done on your main control dial)
- The camera will then choose the correct shutter speed setting to match your aperture.
- Take the photo you'd like to take (***if using a low f-stop, you'll often want to use 'maual autofocus' see Focus post above***)
- Review it on your camera's LCD (zoom into the image to check focus)
- If you don't like what you see, re-adjust your aperture setting
- As with P mode, you can change the exposure compensation to lighter or darker (the camera will NOT change your Aperture setting when it Av (A) mode: it will adjust your shutter speed)

"My photos are too dark!" If you're still having this problem after changing the exposure compensation, you probably have your f-stop to too high of a number for the light that you have available. Either turn your f-stop to a lower number or turn your ISO up to a higher number, or you can try using a flash.

Manual Mode (M)

What you control:
1. Shutter speed
2. Aperture.

Important issue:
The slower the shutter speed, the higher the fstop you'll need to use for a proper exposure
The faster the shutter speed, the lower the fstop you'll need to use for a proper exposure

Manual Mode is where it all comes together: you're now choosing everything, the camera is deciding nothing.    Remember: shutter speed and aperture are bound together: when one goes up the other must go down, and visa versa.  I personally rarely use manual mode, except for when I'm shooting night photos - but you may find that there's a reason that you'd like to use manual mode.

One thing to note about aperture, which is illustrated in the aperture chart in the Aperture Priority section: the lower the number, the more that will come into the camera when the shutter is open, due to the larger opening for light to come into.  If you need more light but can't use a longer shutter speed, increase the size of your aperture: by lowering the f-stop.  Use your LCD to see how your exposures are looking, and adjust accordingly, based on what you learned in both the Aperture Priority and Shutter Priority sections.

If your images are too dark, you need to let more light in by either using a longer shutter speed or a lower f-stop (or by using a higher ISO).  If your images are too light, you need to use either a shorter shutter speed or a higher f-stop (or by using a lower ISO).  Don't be too obsessed with getting perfect exposures on Manual: let the camera do the work for you in Program (P), Shutter Priority (Tv, S), and Aperture Priority (Av, A) modes especially early on.  And remember - have fun with it: the more you work on all of this the quicker and more naturally the adjustments will come, and the more you'll feel comfortable doing - enjoy!

Lenses (and Crop Factor)

Before understanding the lenses that you'll put in front of them, it's important to understand sensor size in DSLR cameras.

Full Frame vs. Crop Cameras
Most brands of DSLR came in two sensor sizes: full frame and crop.  A camera that is "full frame" (Nikon full frame cameras are called FX) has a sensor that is the same size as a frame of 35mm film.  Crop sensors are roughly half that size: Canon crop cameras have a 1.6x crop factor, and Nikon crop cameras (DX) have a 1.5x crop factor

Canon Full-Frame Cameras:
1D series (excluding the 1D, 1D Mark II, 1D Mark III and 1D Mark IV, which were 1.3x crop)
1Ds series (discontinued as of the 1D X, 2012)
5D series

Nikon FX (full frame) Cameras:
D3 series
Dxxx series (e.g., D800, et. al.)

Canon Crop Cameras:
Rebel series
xxD series (e.g., 60D, et. al.)

Nikon DX (crop) Cameras:
Dxxxx series (e.g., D5000, et. al.)
Dxx series (e.g., D40, et. al.)

        Full Frame at 17mm (Nikon - FX)                                                                 1.6x Crop Factor (APS-C) at 17mm (Nikon's DX is a 1.5x crop factor)

IMPORTANT TO NOTE: the photos above illustrate how the same lens will show two different views depending on if it's on a full-frame or a crop camera.  The photo on the left was taken using a 17mm lens on a full frame camera.  The white box - which matches the photo on the right - shows what the EXACT SAME LENS on a crop-camera would capture due to the sensor being smaller.  The lens doesn't change sizes, the area of the image that's captured from the lens changes based on sensor size.   

ALSO IMPORTANT: Canon and Nikon both make lenses designed or use with crop cameras.  Canon crop lenses are called EF-S (think 'S' for 'small sensor') and Nikon crop lenses are called DX lenses.  Nikon DX lenses will work on Nikon full-frame (FX) cameras (but it doesn't make sense to buy them if you have an FX camera because you'll only use the middle of the sensor) but Canon EF-S lenses WILL NOT EVEN MOUNT onto full-frame Canon cameras.  Conversely, all full frame/FX lenses will fit on crop camera, you'll just be losing a lot of the lens' coverage as illustrated above. 

When it comes to buying more equipment for your camera don't hesitate to buy off-brand to save money, except for when it comes to lenses.  The lens is the single most important part of your camera: if you use a bad lens, it won't matter how great your sensor or autofocus system is.  If you're shooting a Nikon camera - buy Nikon lenses.  If you're shooting Canon - buy Canon lenses.  Both companies are primarily optics companies, and that shows in their lenses.  If you have good reason to buy off-brand (or if you want to drop a fortune on a beautiful Zeiss lens) then go ahead, but as a general rule it's much more worth it to get lenses that match your camera manufacturer (especially with Canon and Nikon).

Prime Vs. Zoom
Simple: prime lenses are a fixed focal length (e.g., a 50mm or 100mm et. al.) and zoom lenses have a range of focal lengths (e.g., 28-105mm, 70-200mm et. al.).

Prime Lenses: because there are less moving parts and specifically made for a single focal length, they tend to be much lighter and optically sharper.

Zoom Lenses: They cover a wider range of focal lengths - less lenses to carry around

Ultrawide lenses are any lens that have a focal length 20mm or smaller but are not fisheye lenses (see below).  Note: ultrawide lenses should not be used to try and get more in the photo: they're used to get up close and personal with your subject matter like when I shot these flowers with a 14mm lens.

Fisheye lenses are lenses with an intentionally rounded distortion (between 5.6mm-15mm).  NOTE: some fisheyes are so wide that they make a circular image on your sensor.  Canon makes an 8-15mm zoom fisheye lens that on full-frame makes a perfect circle at the 8mm setting and fills the frame at the 15mm end.    

Lenses roughly 24-35mm

Lenses roughly 40-60mm (they're called "normal" because it's about what the distance that humans see with our eyes.  If you're staring straight ahead and then put up a lens with one of these focal lengths in front of you, you'll see everything at roughly the same size.  50mm lenses are considered the most 'normal' focal length.

70mm + lenses. 

Macro (Nikon 'Micro') lenses alllow you to get super close-up images.  A 1:1 macro lens set to 1:1 is like setting the image sensor on the object you're photographing directly: see an example here of macro photos of eyes.  Macro lenses are amazing for detail photos or photos of small objects like jewelry, insects, etc.  Macro lenses can be 50mm, 60mm, 100mm, 105mm, 180mm, etc.  The longer the focal length (higher the number) the further you can be away from the object that you're photographing at 1:1.  Note too that to photograph at1:1, you'll need to set the lens to "manual focus" and move the entire camera back and forth to focus it.  If you're using a tripod you can make use of macro rails to help out with this.   

Some people refer to 85mm prime lenses as 'portrait' lenses but that's certainly not etched in stone.  There are two basic criteria for choosing a good portrait lens.  First, use a prime lens - primes are much sharper than zooms as a rule, and sharpness is very important for portraits.  Second, use a somewhat longer focal length: 85mm at a minimum.  If you're right in your subject's face they're not going to be as comfortable as if they feel like they have their space.

How many lenses do I need?
Here's the good news: not many.  Today's lenses are made to excellent standards, and you don't need to tote around 300 lenses to get good images.  The fewer lenses you have, the better in fact.  If you want to cover all the bases, have one ultrawide, one normal, and one telephoto lense - all three can be zooms, all three can be primes, or a mixture.  When I'm out shooting 90% of the time I use only my 17-40mm lens on my 5D Mark II, and 90% of the time that I'm using that lens I shoot it at 17mm.  That's me - you might have a much different preferred focal length.  If I do bring along another lens, it's my 100mm macro: those two lenses alone generally cover 99.9% of what I need.  If you're just getting into DSLR photography the kit lens that came with your camera (most likely an 18-55mm zoom) is all you need for now - don't feel like you need "better and more" lenses to take excellent photos.    

What Next?

Have fun! 
DSLRs have made SLR photography much more accessible and simple than ever for learning purposes since you can see the images immediately.  Use this to your advantage: look at your images as you shoot, so you start to understand what's going on with the settings that you use. 
At some point in the future I'll be posting 'additional photo helps' for other topics not covered here.  If there's something that you'd like covered, please feel free to send me an email, thanks!