For Beginners - Your Camera Explained in Plain English

For Beginners – Your Camera Explained in Plain English

Beginner, don’t be dismayed! It can be really easy to understand your camera and how the settings in the exposure triangle work the way they do. This explanation is the way I personally think of my camera as an eye:

  • The sensor in your camera is the brain. It receives data and information.
  • ISO is how sensitive the ‘eye’ is to the light.  The higher the number, the more sensitive the eye.
  • Aperture is like the pupil. The wider it is (the lower the f/stop number), the more light is allowed into the eye. Over exposure is like when you’re inside where your pupils are more dilated to compensate for lower light. When you step outside, everything it too bright and your pupils have to get smaller to compensate for so much light. Then when you go back in, everything is too dark (under exposed) because your eye’s aperture needs a moment to open up and let in the light.
  • Shutter speed is like blinking. The faster it blinks, the less light is allowed in and vice versa.

As painfully simple as this is, it really doesn’t get too much more complicated than that – the explenations just do!

How about everyone else? If you had a total beginner ask you to explain how a camera works, what would you tell them?

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Elizabeth Halford is a photographer and advertising creative producer in Orlando, FL. She wrote her first article for dPS in 2010. Her most popular one racked up over 100k shares!

Some Older Comments

  • danfoy June 7, 2010 12:46 am

    More megapixels does NOT make a camera better - google 'megapixel myth'

  • begginer June 6, 2010 08:04 pm

    This was really helpful. , but I always wanted a camera like the professional photographers use hope I don’t come off as ignorant, but the only way I would describe the camera that I wanted would be that it had to be black, and very bulky.i just know that the more mega pixels the better. Now I stumbled across this site, I’m learning so much more :)

  • Lon June 5, 2010 07:57 am

    Your cornea is the uv lens filter, your "lens" is the glass elements, the ciliary muscles in the eyes zonules are the AF motor, your pupil is the aperture, your retina is the sensor, your visual cortex is the processor, your cerebral cortex is the memory card, your blood is the power supply, your hearth the battery, while your neurons and optic nerve are the circuits that control everything.

    While the design and order of these elements are different, the concepts of how each work are exactly the same. For instance, to complete the analogy, your eyelid is the shutter (except on you it is on the outside and is generally left open, since humans don't take stillshots, we take video). Your eyelids are a lens hood and when you put the lens cap for the night its like wearing a sleeping mask.

    So now all that's left is to come up with something analogous to explain how the eye works (and don't say camera)... Maybe back to the bucket analogy?

  • paige whitley June 5, 2010 06:52 am

    I have used the eye as an example of how the shutter/blink and aperature/pupil works, before but hadn't thought of what would be the sensor.

  • darren_c June 5, 2010 02:08 am

    Lots of great explanations here. It's funny how everyone seems to put things into a way the reflects their own world and understanding. None of them are wrong, just a different way of thinking. SOmetimes we just need things explained in a different way.

    One of my favourite books, and in my opinion a must for any beginning phorographer, is Bryan Perterson's "Understanding Exposure". Really simple description of topics (i.e. Aperture, Shutter Speed and ISO aka the exposure triangle) and great visuals to demonstrate.



  • Steve J June 4, 2010 02:50 am

    I show them the episode of the Flintstones where they are taking a picture and it shows the bird in the camera chiseling out a picture. :D

  • Pam June 3, 2010 04:04 am

    I use the eye to explain as well. It's not 100% exact, but for someone who has absolutely NO CLUE what the correlation between aperature/shutter speed/iso is, this does explain it quite well and gives them enough of an understanding of how a camera works.

    Nice article!

  • Andres June 2, 2010 11:49 pm

    I don't agree with the analogy that the sensor is the brain. The sensor does not store the image nor does it analyze it or modify it in any way. The sensor is more like the back of the eye; the retina, macula and fovea to be more precise. (

  • Jim News June 2, 2010 03:06 pm

    Nice article. You've given a simple primer on the basics of how a camera works. The sensor is the brain because it records what the eye sees. Well done!

  • Sapphire June 2, 2010 01:54 pm

    This post is PERFECT! I have people ask me all the time about how to use their camera and this post makes it extremely easy to explain. I always mention this blog as the best starting place to visit when learning to use a camera. Thanks to DFS (mainly) and other photography tutorials online I was able to get a job! I had 3 weeks to learn to use my DSLR! It's been fun!

    Much appreciation to everyone at Digital Photography School! Cheers!

  • Andreas June 2, 2010 02:23 am

    The blinking part does not make any sense to me. Although I wish I could see in the dark with "slow shutter speed". And do one really need an analogy for such a simple consept? If so, the bucket, or glass analogy is much better IMO.

  • Jeff June 2, 2010 12:51 am

    This is how I think of it too, and it makes sense because the camera is a simulation of the eye, in the first place. The retina is not only "like" a sensor, it really is a sensor. The only weak part of the analogy is the ISO, the bucket / hose analogy works better there.

    To add to the aperture part of the analogy, you can explain depth of field too: if you want to see something far away, like on the horizon, you probably squint your eyes. I.e. making the aperture smaller to increase depth of field. It may not actually work like that but it fits the analogy anyway.

  • Jeff June 1, 2010 02:06 am

    If I had a total noob ask me to explain basic camera functions, I would define the sensor as the eye. For the sake of simplicity, probably no need to mention there is circuitry (the "brain") in the camera that processes and stores what the "eye" (sensor) sees. I like to explain aperture size like a slice of pie. I get them to understand that the "f-stop" represents a "fraction," and everyone understand that the larger the denominator, the smaller the slice; 1/8th of a pie is bigger than 1/16th of a pie. Since I've already explained that aperture controls amount of light, I would explain the shutter is like a blinking eyelid. How fast the shutter blinks determines the amount of _time_ light is allowed into the eye.

  • Nosti June 1, 2010 01:20 am

    I always got confused with the aperture until I started thinking of it in this way:
    Big numbers mean more of the opening is covered -- which allows less light. It's the same principal--just easier for me to grasp this way.

  • Jack Tarantino June 1, 2010 01:19 am

    The part about the sensor is completely incorrect. The sensor is not the brain. The sensor is alike to the retina in the back of your eye. It is the rods and cones that actually capture information and then send it along a bundle of nerves to the brain. Cameras(digital ones anyway) have a brain. It's what we call a processor. That's why when you buy a DSLR, the packaging or the webpage will usually tell you what kind of processor is in the camera. You want to know if it's a smart camera or a dumb one. I didn't mean to sound like a dick at all but my years of experience in related fields where highly offended when you called the sensor a "brain".

  • Lynda June 1, 2010 12:43 am

    Nice and simple, but you should probably change "explenations" to "explanations" in your article.

  • cgenesis99 June 1, 2010 12:10 am

    That is an awesome explanation! It's so simple but I totaly get it in that manner. I'm new to digital photography , I have a Cannon T1i and get so frustrated because I want to take the best pictures possible . So thank you, that puts things more into perspective.

  • Lon June 1, 2010 12:01 am

    I like the use of eye analogy, and you pretty much got the ISO and aperture comparisons correct but shutter speed is like the opposite of blinking (this could be confusing to someone with no understanding of how to expose a photo)

  • Laurie Roy May 31, 2010 10:45 pm

    I really like the eye explanation....I am one of those newbies and I am forever going to take a picture and I stand there stairing at the settings on my camera trying to figure out which way im supposed to move all the settings. I've been shooting in just manual for the last 3 months and always used only auto before that. For the most part im starting to get the hang of it until all of a sudden I think I have it set right but then a red AP sign comes up sometimes and I really dont understand how to get away from that.

  • OJ Photography May 31, 2010 10:00 pm

    Well done. I often get asked by people with absolutely no camera knowledge and I have a hard time explaining it to them but this will help!

  • Karen Stuebing May 31, 2010 08:56 pm

    My first film camera (Pentax K1000) came with a little booklet explaining the basics. ISO back then referred to the type of film you should use for different shooting conditions.

    To be honest, I don't really remember how it explained it but after a few rolls of film, I was up to speed. Yes, there were a lot of bad photos too. :)

    I think they used standard f stops for things like scenics, close ups with shallow dof, etc and then you compensated with shutter speed. And you started out with a prime lens. No telephoto. You had to physically move in and out.

    The analogy here is a good one. I can't think of a better one.

  • DerSepp May 31, 2010 07:14 pm

    Totally confusing metaphor in your article: Brain as sensor, lol.

  • foo May 31, 2010 01:05 pm

    forgot to add to the cup analogy:

    Cup fills to the brim = Perfect exposure
    Cup overflows = Over exposed
    Cup not filled up completely = under exposed

  • foo May 31, 2010 12:59 pm

    i prefer the filling-up-a-cup-in-the-rain analogy.

    Diameter of cup = Aperture. The wider the diameter, the more water can drip in.
    Depth/Height of cup = ISO. The deeper the cup, the more water is needed to fill up. Deeper = lower ISO.
    Cup Cover = Shutter speed. Time b/w opening and closing the cover.

    How heavy the rain is = amount of light. The heavier the rain, the faster the cup fills up. This is important as different situation calls for different balance of the exposure triangle. Heavy rain = Bright light.

    This leaves the user to decide how they want to fill in the cup because the different permutations of a correct exposure can result in different effects (DoF, motion blur, noise, etc).

    I leave out the explanation for sensor because it doesn't really matter in terms of exposure. I'll just explain it as it is when they as about sensors and megapixels. They usually get it, or they just leave it for another day.

  • Jessica Oei May 31, 2010 11:38 am

    I use the eye analogy as well-- it makes sense especially since lenses were modeled off of how eyes function! I like your over/under exposure analogy, that was very nice.

  • dan foy May 31, 2010 11:02 am

    The eye analogy is the same one I use, although shutter speed as blinking is a nice refinement! The analogy makes sense because a camera is literally a reproduction of the eye.

    However, calling the sensor the 'brain' is misleading because the sensor doesn't do any 'thinking' at all, it merely captures data. In the eye analogy, the sensor plays the part of the retina. If you wanted to call something on the camera the brain then it would be the processor (or, to the beginner, the rest of the camera body). The processor meters and decides exposure (if the camera is in an auto mode) and interprets the data recorded by the sensor into an image for outputting onto the LCD - both of which are functions of brains.

  • Mei Teng May 31, 2010 10:55 am

    You gave a very good explanation that's easy to understand. Thanks for sharing.

  • Sally Erickson May 31, 2010 10:25 am

    Thank you, best explanation yet.

  • yt May 31, 2010 09:10 am

    I do not see it as brain, information, data and all that. Maybe I'm coming from film thinking, but I use an analogy of filling a bath tub with water.

    The amount of water you desire to have in the end is the target exposure, or for beginner, 'how bright the picture looks'. The tap is the aperture - the more you open, the more water gets in, faster it fills. The time required to fill the tap is the shutter speed.

    So you can change the tap opening / time required relationship to achieve the same amount of water in the tub. But you can also add more time or open tap more for the same amount of time to intentionally over-fill the tub. When you want that extra water for some reason.

    In a sense, it is a real-life analogy but is very similar to how film actually works. If somebody is interested enough to ask the question about how the basics of camera work, I'd try to give them some explanation which they can demonstrate themselves (they can see how water fill the tub, but it is hard to see the eyes work, though they think they understand it because that's what you learn at school) so they can work on it with intuition.

    Having said that, maybe this explanation works for me because I grew up having a bath in a tub every night!

  • michael lastimoza May 31, 2010 09:07 am

    are you sure that the sensor acts as the brain? I'm confused, i think It's the eye it self....

  • Jen at Cabin Fever May 31, 2010 08:42 am

    I agree with the "automatic mode" tip. When you take a photo look at what settings your camera 'chose'. Look at many different photos in many different settings and you'll start to see in what conditions your camera chooses different settings.

    And when I explain basic camera operations to people I always use the eye as an example as well :)

    Cabin Fever in Vermont

    NEK Photography Photo Blog

  • Douwe de Boer May 31, 2010 08:41 am

    Of course you might think the eye works like a camera. I think it's not the best metaphor. 'Cause when you blink fast your vision doesn't get "underexposed". The eye only has a pupil to control the amount of light that comes in.

    I always think of an garden hose (a full bucket of water would be a good exposed picture I guess).
    Aperture = Thickness of the hose
    Shutter speed = Time the tap is open
    ISO = Water pressure
    All three elements play a part in filling a bucket of water.

    Or am i saying something stupid?

  • Amit Mittal May 31, 2010 08:24 am

    Ah! Someone finally put this down, I was too lazy. On more than one occasion I have used this very analogy to explain the various pieces. And since it is now documented, I can just share the link. :-)

  • Teresa May 31, 2010 08:01 am

    Hi. I like your article, but I wanted to tell you that you misspelled "Explanation". Feel free to delete this, I just wanted to tell you. (I would want to know).

  • 365 Photography Tips May 31, 2010 07:00 am

    After having undersrood the concepts, a good way to master them effeciently is by observing the camera's behavior in automatic mode. This allows you to understand the interaction between the aperture, shutter speed, ISO, etc.

  • Prateek Ahuja May 31, 2010 06:34 am

    This is really simple and easy. Quite a nice way to make understand. Great one Liz.
    I make others understand thru examples which I believe is another great way.
    Thanks for this!