Digital SLR Beginner – Understanding Shutter Speed, Aperture and ISO

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

Digital SLRs are dirt cheap these days. We see more and more people purchasing Digital SLR on a daily basis but quite often these newbies are also pretty much disappointed at how they were promised beautiful pictures yet fail to achieve.

The most common problem would be the lack of understanding of Shutter Speed, Aperture and ISO – the 3 fundamentals of capturing image, and capturing it properly.

In fact many I’ve got to know many who are new when it comes to photography, and it’s been the same question time and again and I’ve been spending quite a fair bit of time explaining this and that. So now here it is – my (simplified, as usual) version of explaining how Shutter Speed, Aperture and ISO works.

While far from being the best when it comes to explaining the fundamentals, I do hope you still gain some knowledge after reading this article.


Always keep it in mind that what a camera does is capturing light.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

What you see through the viewfinder is what the camera sees. The light enters through the lens, hit on the on the mirror and reflected as to what is shown on the viewfinder.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

When the shutter button is pressed, the camera takes the shot based on the shutter speed, aperture and ISO set on the camera – these 3 factor holds greatest influence on the exposure of your shots. The aperture blades close in, the shutter lifts and the light lands on the sensor, the camera captures it.

Don’t worry if you don’t know what those terms mean, continue reading the article and you’ll understand it better as I elaborate.

Remember, no matter how good your composition is, ultimately it’s the exposure that determines whether your shot is a success. And to get the correct exposure, you’ll need to know how to balance these elements to get the right amount of light to make the shot look right.

While this article talks about the Digital SLR, the same concept actually works for SLRs (referring to the non-Digital types). The difference would be that light would be captured on film instead of light sensors.

What is Shutter Speed?

So what is shutter speed? Shutter speed is the setting on your camera that decides how long the shutter should open. The longer the shutter opens, the more the amount of light is captured on the sensor. This is a mirror though, behind it is the shutter, which is right in front of the sensor.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

Think of it as your eye lids. The shutter is basically a closed eye lid, once the shutter button is clicked, the eye lid opens and closes. By setting the shutter speed, you’re telling the camera to duration to keep the eye lid open.

For our human eye, the longer the eye lid is open also means more light has entered the eye. Stare at some bright lightbulb for half a second and your eyes barely hurt. Stare at the bright lightbulb for 5 seconds and you’re stuck with the ghost of the lightbulb. The same concept applies to shutter. Assuming all factors (like aperture and ISO) remain the same, the longer the shutter is opened, the more exposure you get – which is why another common term for Shutter Speed is EXPOSURE TIME.

I prefer to use the term EXPOSURE TIME as I find it to express the purpose of having the shutter movement better, but for the sake of this article I’ll use Shutter Speed as I think it’s the more commonly used term.

What is Aperture?

Aperture refers to the diaphragm opening inside a lens. How wide the aperture is open is indicated by the F-number. The lower the number, the wider it is. The wider it is, more light goes through it.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

Think of it at your eye lids again, but instead of being the duration of the eye lid being kept open, aperture is like how wide your eye lid is to open.

or here’s how one of our readers thought of it….

“Think of it at your pupil size, in a dark room your pupils get wider and lets more light in to your eyes. On a sunny beach your pupils retracts and get smaller.”

When you set the aperture value to the lowest value available (meaning widest aperture) then it would open the aperture blades as wide as it can. The aperture will close to the width as indicated by the setting in the camera. Increase the value and the aperture will reduce in opening size accordingly.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

The aperture available depends on the lens you’re using. The F-number will also be displayed on your camera’s indicator, in the image below we see that the aperture is indicated – at f/2.5

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

The aperture also affect Depth of Field, however I will cover this in one of my upcoming articles as it can get pretty lengthy.

What is ISO?

ISO is all about sensitivity, in the case of the Digital SLR – it’s about the sensitivity of the sensors. By setting the ISO, you’re telling the camera how sensitive it should be when it comes to absorbing light. The higher the ISO setting, the more sensitive the sensor is towards light.

Think of the camera sensor as your retina. The ISO setting basically tells your retina how sensitive it should be πŸ™‚ Too bad it’s not possible to tell your retina how to behave.

Do remember that higher sensitivity also means higher NOISE level, it’s not that it’s bad. Some people are picky on noise. Others just couldn’t be bothered. Noise is more noticeable on the darker areas of a picture, you’ll see those tiny little dots that resemble little grains.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

Notice the noise on the darker parts of the picture?

Working the 3 For Exposure

Now that you understand (hopefully!) all the above – it’s a matter of understanding how to work the 3 of them to achieve a balance that results in correct exposure.

Now don’t be afraid, you won’t be losing anything except for your shutter’s wear and tear, and also a little bit of your time. πŸ™‚ With that, you’ll be taking better pictures in no time!

Just remember that the sensor needs to capture the RIGHT amount of light. The wider the aperture available, more light is able to enter within the X amount of time thus you can use faster shutter speed. On the other hand, the faster the shutter, the less light that enters. πŸ™‚

In the event that your desired aperture and shutter settings still couldn’t get you the right exposure, adjust the sensitivity ISO.

What To Look Out For?

I hope you enjoyed this article so far. If you have any questions, feel free to ask.

Do visit me from time to time, subscribe to the RSS feed to get instant updates on new articles.

Anyway, I’ll be coming up with a few more articles. πŸ™‚ Such as how to use exposure (shutter speed if you prefer) and aperture to achieve beautiful effects on your pictures.

Digital SLR Beginner - Understanding Shutter Speed, Aperture and ISO

90 thoughts on “Digital SLR Beginner – Understanding Shutter Speed, Aperture and ISO

  1. great write up on the fundamental questions beginners normally ask. i too had a hard time understanding the first time i was into dslr. then after playing around with the dslr i got to know better πŸ˜›

    i like how simple it is you explained about those 3 terms πŸ™‚

  2. Useful information!
    looking forward for more…
    and wanna ask, for beginner and not much budget, which dslr you recommend…
    i heard of sth like semi dslr… is it reliable and which is better?
    full or semi…

    and what brand should i prefer, i terms of compatibility of lens, price, performance?

  3. @Johnny – well, you’re one of them – right? πŸ˜›

    @clem – sure!

    @Joshua – thanks, however I decline to turn this article into a What Camera For Me thing. πŸ™‚ You could read one of my articles about types of digital camera (it’s in the photography section) OR you could just contact me via MSN since I’m already on your contact list. πŸ˜€

  4. Nicely done article here. Learn alot about those terms in DSLR as well. Keep up the good work. Awaiting your future article them. Why not they explain about different lenses as well? Since i guess beginners like me would be interested with them πŸ™‚

  5. A good article for beginner.. Its time for article about the exposure.. Even till now i still cot fully understand about the exposure thing..

  6. Goldfries …. this blog is one of my camera study last time which i found on the
    Besides that, i also saw some of the painball photo shoot with 18-200mm OS sigma lens..

  7. I think no need for me to attend the photog class… because all explaination here totaly understandable by me…especially the ISO issues…Thanks again goldfries…Keep on coming the good articels and I’m eager to know more from you…

  8. I really enjoyed your article even thou I learned these fundamentals at a course I took some years ago.
    Well anyway I had an idea as to how to maybe enhance your analogy about aperture a bit:
    “Think of it at your eye lids again, but instead of being the duration of the eye lid being kept open, aperture is like how wide your eye lid is to open.”
    “Think of it at your pupil size, in a dark room your pupils get wider and lets more light in to your eyes. On a sunny beach your pupils retracts and get smaller.”

  9. Just wanted to say thank you for the simple yet informative posts that you have. Thank you for putting in the effort and sharing your experience! πŸ™‚

  10. Nicely done. Much better than my lecturer who’s being paid thousands. =) Looking forward to your next one.

  11. Due to an Imedia teacher being on long term absence, and being the only one who knows the basic on camera my school put me forward to do my school Imedia classes… Panic…. until I found your articles, so thank you so much πŸ˜‰

  12. good info about the working of camera and basics, but how can i guess exact settings for shooting a picture in daylight or indoor or in dark, will it be developed by practice or we can have a fixed for the particular scene,
    Thanks for the Info..

  13. ehh, you don’t need to guess. πŸ˜€

    it’s all there, even in manual mode, as you adjust the settings, there’s this metering gauge there that you just adjust it to reach 0, which is what the camera thinks is correct.

    shoot first and see if you need to expose it further or lesser.

  14. Thanks for showing me to this article on ur website..

    By reading it, I can understand better now.. Thanks again!

  15. Helloo…seriously your articles broadens my knowledges about photography…i give u credits for that…good job bro…keep it up….to the newbies out there…this article will help u alot…trust me…im a newbie too

  16. ERM.SO anyone can tell me what is all about of RAW-Jpeg is……….?and how it’s works for us?

  17. Thanks man… I’ve been looking for an explanation like this.. it was of great help… thanks a lot.. πŸ™‚

  18. Thanks man… I’ve been looking for an explanation like this.. it was of great help… thanks a lot.. πŸ™‚
    I’m just a dslr beginner

  19. Its really fantastic . Specially for those who live where they can’t find such a formal education in their home country (Ethiopia in my case) it a priceless gift. Thank you .
    very very DSLR beginner.

  20. goldfries,I’m a beginner. I understand how shutterspeed,aperture and ISO works. But something I’m not sure how to comtrol. In a scene where I took a picture, I found that the picture is under expose, which 3 should I be adjusting first? Should I stick to the aperture size and adjust shutter speed or vice versa? Or perhaps both? I’m kinda in dilemma when choosing which to adjust.

    If I adjust both ( let say dec shutterspeed and inc aperture size), how much of shutterspeed and aoerture size should I adjust to get it right? is it a trial and error technique?

  21. Ax,
    It really depends on the situation. In most low light scenarios, I usually bump the shutter down to 1/60th, the aperture down to as low as it goes, then adjust the ISO as needed to get the correct exposure. I’m sure other people have different techniques, but that’s mine.

  22. Wow, I got so busy until I missed out Ax’s question. Thanks TJ!!

    For most people, I believe the aperture and ISO are the limitation. So that’s where the shutter speed is lowered to allow more light but this depends on the scene. For scenes with movement, then going slow isn’t ideal.

    In some cases where like say I’ve already used the highest ISO available (like ISO 1600 on my 350D) and widest aperture that I want to use, like say f/4. I then need to lower my shutter speed………. but then for a decent exposure it’s already 1/30.

    So what else can I do?
    a) I could compromise with the aperture, going say f2.8 or something so I get 1 stop more light so I could have 1/60 shutter speed.

    b) or if not, I could under expose the photo and brighten it later during post processing. (RAW would be better for that). I’ve done some shots that I shoot it 2 stops below the metered exposure and push it back up!

    In the end you need to know that photography doesn’t mean you must always capture at the PERFECT exposure. Sometimes some sacrifice need to be made to capture the moment, that includes accepting high noise and even to go to the extent of under-exposing.

    Just ask yourself. Would you rather a blur shot? no shot? or at least a short with decent capture and hope to save it with PP? I’ll go with the last option, having something to try to save is better than having nothing or something you can’t save.

    @Tewodros – video mode is different. It uses ISO for sensitivity, aperture for the depth of field but the shutter is always open so that the light is constantly hitting the sensor to be capture. On cameras like the 550D / 7D and whatever else, it’s just a matter of going to video mode and click record! πŸ™‚

  23. AWESOME! I’ve been looking for this since I just bought the nikon D3100. It’s time to get to know those basic stuffs~ cool article! Thanks heaps!

  24. Dear Guru,
    I was so confused on the terms howevr you made the anology so easy i can only bless you for your explaination.

    May god bless u Guru……..

  25. Since i know about shutter speed and all those stuff i need a dslr as a beginner. can anyone recomend some dslr.

  26. thanks ya!!! i own nikon d3100 for almost half year and i sometimes still confused with shutter speed and aperture… oh my… at least now clear a bit… hahaha… just wanna ask,how to take nice picz? sometimes took many picz but just not the picz that i want…

  27. That one you have to look under the section IMPROVE YOUR PHOTOS.

    Need to write more for that section though. Understanding these settings only open door for you to get nice pic BUT to get nice pic you’ll have to improve composition, learn how to frame the subject.

    Depending on the nature of photo, you’ll even have to depend on other factors
    a) timing
    b) lighting
    c) communication
    d) planning
    e) luck


  28. Hi. It would be good if you can email me instead of answering it here.

    My question is: When I can’t take picture when I zoom in? I am using Canon Dslr 500D.

  29. Hey there! I think you did a great job explaining it > but being a newbie, I wish you would have given a setting example. ie: the shutter speed, iso and aperture on a sunny day. Hahaha That’s my issue. My camera Nikon D60 just wont take a picture and I don’t understand why. Guess I have to play with it more.

  30. Thanks!

    It’s impossible to give you the correct settings as the SUNNY day could be really different as well! for example, if on a sunny day and you’re facing the clouds, the scene actually appears brighter than say a sunny day where the it’s cloudless.

    About exposure, since it’s made out of 3 components, there’s no fixed way of doing it,

    Once you understand the technicalities, you’ll see how the exposure at ISO 100 | 1/2000 | f5.6 is going to be the same as ISO400 | 1/4000 | f8. πŸ˜€

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  32. im really interested in the pentax kr dslr camera
    what is your view on the pentax k r?
    doe it work well in low light/indoor setting?take in more light? i dont enjoy using flash for i feel it ruins the picture

  33. Hi,

    I like your article very much and the use of the eye as an example is really. Thanks for the info.

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  38. Nice one !.. But i have just buyied Canon Rebel i3 .. i need to understand this camera .. if you have anything more please let me know .

  39. Very nice article. You covered pretty much all the basics. And you explained it on 350D, My first dslr πŸ™‚

  40. Hellow……….thanks sir you explain almost all basic in very simple way …….. very nice article………sir i heard cannon provide some softwares which we install it in our caera for better performance ……. so i want to ask u that is cannon really provides such softwares or not????????? & how much can that softwares really improves camera’s performance………

  41. I am amatuer photograher. I love your article easy to understand. I want to be a real good photograher needs to improve my understanding with the 3 exposure. Thank you for sharing your expertise to us. You are now my mentor.

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