For many, a photograph where the subject is sharp while the background is completely out-of-focus is what they consider an “advanced” photograph that can’t be done with consumer cameras or lenses, the effect just makes the subject pop out of the frame.
Many people assume that you’re required to own either a long telephoto lens or a very wide aperture lens in order to do so.
This tutorial is for beginners or for those who haven’t bought an expensive telephoto lens or wide aperture lens.
That premise is partially correct, owning either or a combination of those two lens features will give you that look you’re after, but without the knowledge of how it is achieved, you’ll be spending needlessly for something that may be done with your existing equipment.
You can get a blurred background with a sharp subject even with a point-and-shoot camera or your DSLR’s standard kit lens as long as you understand the physics involved. The only difference is, with longer and faster lenses, you can induce more blur than basic equipment. Once you understand why and how to “separate” the background from the subject by controlling depth-of-field, you can apply this knowledge to other forms of photography like macro, still-life, etc. regardless of camera type.
By definition, depth-of-field (DOF) is the area from front to back where the scene is acceptably sharp. Areas that are no longer sharp are known to “fall out” of the DOF. The larger the lens opening (aperture), the shallower/thinner the DOF, the smaller the lens opening, the deeper the DOF – with all else being equal. Controlling DOF means to control how much of your subject should remain sharp.
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If you refer to the photos below, aperture controls how much of the scene stays within acceptable focus. Compare the sharpness of the two power fuse boxes in the background with the blue labels.
- @f/2.8
- @f/25
The first photo was shot with a large aperture (f/2.8), the area of acceptable sharpness doesn’t go beyond the incense holder, rendering a blurry background as those elements fall out of the DOF. The second photo was shot with a small aperture of f/25, the DOF extends about 4ft behind the incense burner and more details can be seen in the background. The two photos are shot at identical distances from the camera.
While aperture controls how much your DOF has, the distance of the background in relation to the subject and camera plays a big role as well. Check out the next two photos. Even at f/32, the second image fails to render the pier cranes sharp as the background is too far off (about 4km away). Even with modest aperture opening of f/3.5 in the first photo (typical consumer lens maximum opening), the background is virtually detail-less due to the distance factor.
- @f/32
- @f/3.5
The illustration below pretty much explains everything. Keep the camera close to the subject while keeping the background as far away to the background as possible to get the blurriest background possible.
The top diagram will result to a blurrier background because the subject is farther from the background, while the bottom diagram will produce a rather much sharper background in relation to the subject.
In addition, if you double your focal length (20mm to 40mm, 40mm to 80mm, etc.) while doubling the subject-to-camera distance as well (10ft to 20ft, 20ft to 40ft, etc.), you’ll get the same DOF as well.
The series of photographs below are all shot at an aperture of f/4, which isn’t considered as a large opening for lenses and is usually available for most cameras and consumer lenses. With the photos below, take note on how the background (beyond the steel orb) looks.
Image 1 – Focal length 24mm, f/4 – Subject (round object) was about 5 feet from the lens.
Image 2 – Same settings as above, 24mm @ f/4 – Subject was positioned at the lens’ minimum focus distance of 1.5 feet. Notice the much blurrier background, even at a wide-angle, f/4 setting.
To induce more background blur, we can zoom into 50mm and try the same techniques above:
Image 3 – Focal length 50mm, f/4 – Subject about 5ft from lens.
Image 4 - Focal length 50mm, f/4 – Subject at minimum focusing distance. By using a longer focal length, our DOF gets thinner, hence we get more blur.
At maximum zoom 105mm f/4 shot at minimum focusing distance, the effect is maximized (for this particular lens).
Take note, however, that even at 105mm f/4 settings, if you increase the distance between the subject and the camera, the DOF will shift and we’ll get more area in focus. The photo below has the exact same setting as the previous image, but I moved back several feet.
As mentioned previously, this effect is best if either a wide aperture or a long lens is used (or a combination of both a long lens with wide apertures) such as:
Canon EF 200mm f/2.0L IS USM @ f/2.0
Canon EF 85mm f/1.2L USM II @ f/1.2
Canon EF 70-200mm f/2.8L IS USM @ 200mm f/2.8
The images above created lovely separation between the subject and background and the results are really pleasing, but the cost of the lenses above are quite high and may not be feasible for most users.
Don’t fret, you can still get nice background blur with cheaper alternatives such as the ones below.
Canon EF 50mm f/1.8 II @ f/1.8 – $80
Vivitar 200mm f/3.5 manual focus lens from the 1980′s (and other equivalents) – $50 up
Fujinon 55mm f/1.9 manual focus lens from the 1970′s (and other equivalents) – $10 up
If you’re a point-and-shoot camera user, just zoom in a little and activate your macro mode!
Canon PowerShot S40 @ 70mm equivalent
Fuji FinePix F30 @ 38mm equivalent
One last and important note, pick neutral backgrounds with minimal details to produce a pleasing, non-distracting background. Picking backgrounds with high amount of details (such as a crowded street, wall plastered with ads, etc.) will reduce the impact of background-to-subject separation.
So before assuming that “my kit lens can’t do that, I need new lenses!”, understand that your kit lens and pocket camera can give you the look you want for your portraits if you follow the simple physics behind it.
But if you do have the budget, go treat yourself to a high-end lens :)
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About David L. Tong
Glad it's helping folks out, Dom :)
I learned a lot Mr. David Tong! Thanks for providing this site :)
Welcome to the site Edu :)
I like the way you put it sir… The Physics of Photography :) well, i will really maximize my 18-55mm :)
VRy interesting to read it :P :D
stumbled to your site and i admit i am very happy to know that there is someone who can help those who are newbie to photography just like me. reviews like this is great. now i can learn more without enrolling myself to a class. more power, will make time to read more of your reviews
I’m happy to have new visitors to my site. Happy to know that the articles help others :)
Thanks and welcome, Adrian. Please subscribe to my newsletter if you have the time :)
Great blog sir! short but very informative read:D
keep it up.
Rhoel: no it won’t as the Canon pin pattern is different from Nikon’s. It won’t even fire if mounted on cam.
Nikon contacts: http://a.img-dpreview.com/reviews/NikonD50/Images/hotshoe.jpg
Canon contacts: http://a.img-dpreview.com/previews/CanonEOS5DMarkII/Images/hotshoe.jpg
However, if you’re triggering (firing) the flash off-camera using a trigger (radio or optical) then only the center pin is used. In that case, virtually any flash would fire as long as the voltage falls within range.
Lastly, there are a lot of 3rd party flash guns that will work (ETTL) on your Canon. Flash units from Sigma, Metz, Sunpak, Nissin, etc. are all viable alternatives.
hi david, will a 3rd party ETTL speedlite that sez “FIT FOR NIKON”, work for a CANON? some say it would while others say it probably won’t because of shoe contact issues……will the photo guru enlighten me on this please?
Just think of it as saving you the money from buying an expensive 2.8 zoom for now hehehe. Good luck with your purchase. Your flash will take a lot of crisp and sharp images of your daughter :)
I hate you David. Because of your website, I came to appreciate the use of flash, so much that I am saving up for an SB400 or SB600. And now, because of this article, as well as your review of the cheap 50mm prime for Canon, I am now lusting for the relatively inexpensive 50mm Nikkor af-d. I have got to limit visits to your site man, or else, I’d have to home school my daughter when the time comes she has to study.
Unfortunately, it’ll much harder with wider focal lengths as the DOF is physically “deeper” as the lens goes wider, that’s why ultra wide lenses usually have no issues with getting everything in focus.
Wonderful tutorial.
Is it possible to get a shallow DOF while using a short focal length like say 18mm? Is there a way around it without using close up filters?
Hi J^Duhudes, the K20D is a very very capable DSLR, it’s been out for quite some time so I’d suggest you google the usual extensive review sites like dpreview, imaging-resource, etc. for an in-depth analysis of the camera. Good luck to you! :)
hi David, I am in the position of buying a K20D Pentax DSLR, do you have any comment regarding this cam? thanks for the tutorial!! really helps a lot.
nnchong: You’re most welcome, feel free to email me if you need anything :)
this is such a nice and interesting read! it made me really understand what i was reading in my camera manual… you were able to explain it in layman’s terms! thanks so much! :)
Glad to help :)
this blog is so informative for newbies like me….as roli sez…u get to convey what we thought were so difficult issues to laymans terms for us newbies…luv this blog…more power sir david
Thanks for the articles you have shared to us, articles like this are a big help to us who are starting out in photography.
It is also good to know you played airsoft :)
Again a big thanks.
Thanks for the article Sir David! You have a way of describing complex concepts with simple words. That leads me to better understanding the whole thing. :)
Email me specific photos you want to share :) my email’s available from the contact page :)
Thank you for your response.
Your right, I think I should get a prime together with the kit, maybe 80mm f/2 will do.
If you have time would you mind checking my photo stream? and leave some C&C so I would learn more.
Thank You in advance again.
Hi Ronald:
Yes, your assumption is correct. With variable aperture lenses, you have to determine what f/stop does the lens close down to at different focal lengths, so with your 75-300, if you’re using a crop sensor, I’d say 80-100 would be a pretty good focal length to use for head/shoulder portraits. The important thing is to train your eyes to find neutral backgrounds like clumped foliage, shooting downwards to use a bare cement floor from an angle, plain walls, etc.
If you’re getting a DSLR with kit, usually a fixed prime of about 50-80mm would be a great addition for portraits, I’d choose that over a longer consumer zoom if that’s your main purpose. 85mm f/1.8 lenses are common for most brands and they’re priced really well.
Good luck and feel free to post your images here when you have the chance.
Thank You!
So for example if I am to get a 75-300mm f/4-5.6 i really don’t have to walk right close to my subject, and i just need to adjust the focal length and maximize the aperture instead so I can get a blurred background for portraits? Is that right?
I’ve got a P&S with a focal length of 5.8-23.2mm and a max aperture of 2.6 and I’m really having a hard time doing this unless i move really close to my subject. I have plans of getting a DSLR next year and I’m just trying to anticipate w/c lens should I get besides the kit.
Thank You in Advance!
You’re most welcome, we all learn form other people’s experience, I’m glad that the blog is helping others out. :)
can’t say thank enough! a big help to those starting in photography. :) even to me with so-so experience. thanks!
Yes, but there are a lot of creative compositions on portrait that can be done with wide angle lenses as well, so experiment, experiment, experiment. :)
i,m new at dpp and your articles are a big help to ‘new’ photo buffs.
i guess the only problem is when you have a short focal length and try to get close (head and shoulders) to the subject is distortion, specially portraits.
Hi Joaqui: The LX3 is a WONDERFUL camera, you’ll have great fun with that cam. :)
Love the article! Can’t wait to apply the principles learned here on my LX-3!
Hi Jhing,
Your name does sound familiar… Please send my regards to the R1B guys if you do see them.
Anyway, photography is like airsoft as well, you have to be patient to get a good shot instead of “ratrat” mode, the principles of keeping yourself steady when holding a gun is similar to holding a camera, so don’t pressure yourself when starting out, just go with what’s comfortable and be patient.
Thanks for the visit bud.
-Dave
its good to see masters like you post articles like this, learn something new everytime i visit your page.. keep it up..
we used to play with you guys… im from R1B. just starting out in this hobby… nice articles
This is an awesome reading material for those starting out. I really read all your articles. keep it up.