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Possible Duplicate:
How can I get dramatic shallow DOF with a kit lens?

Is it possible to generate shallow DOF with a "kit" lens, and how?

In my case, I have the Nikon D7000 with the 18-105mm f/3.5-/f5.6.

I am exploring my new camera and learning photography as I go. I have a few things in my head i want to learn how to do early and one of them is take images where the background is blurry behind a subject, so to make super nice portraits.

So far, all my initial shots have everything in focus. How do I get a shallow DOF effect? Or can I even do it with the kit lens?

marked as duplicate by chills42 Mar 4 '11 at 14:33

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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I gave pretty much the same answer before, but here it is again for completeness. To minimise DOF and get the blurred background effect you should:

  • Use as long a focal length as possible.

  • Use a wide aperture low f/ number (but don't zoom out increase the f/ number as the actual lens opening gets no bigger)

  • Use as close a focussing distance as possible (but don't zoom out to get closer). Depth of field diminshes very quickly with focus distance, so much so that it becomes a major problem with macro photography getting a non blurred background (or subject!)

  • Compose so that the background is as far away as possible. The further away objects are from the focussing distance the blurrier they will be.

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    Zooming out to get closer is the best way to limit DoF (staying within a reasonable range to avoid perspective distortion) -- and in this case it also has the side benefit of allowing a larger maximum aperture. The key is to keep the framing of the main subject the same. Long lenses don't give shallower DoF as much as they give greater enlargement. – user2719 Dec 23 '10 at 2:07
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    @stan I'm afraid that's not the case. Zoom to 18mm f/3.5 and shoot a subject 18 feet away and your depth of field will be infinite (everything behind the subject will be in focus). Back up to 105 feet and zoom to 105mm f/5.6 to get the subject the same size and your DOF will be 77 ft total, and everything 50 behind will be blurred. – Matt Grum Dec 23 '10 at 13:15
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    I think what Stan is staying is correct...from a "framing/composition" perspective. Granted, the actual physical size of DOF can be an interesting technical discussion, but that isn't really the point of the question or the answers that should be provided. The point is to get the thinnest possible DOF for a particular framing of a subject, and what Stan has stated is correct. Using a wide angle lens with a wide aperture at a very close distance will produce the thinnest (most limited) DOF possible for a particular subject framing. – jrista Dec 28 '10 at 21:19
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    @jrista The statement "Zooming out to get closer is the best way to limit DoF" is not universally true there are cases when you will get a larger DOF so I can't agree that it is the best way. It's true you mostly gain only magnification with a long lens however there is a point at which DOF increases when you zoom out to maintain subject size (I assume this is what you mean by "same framing"). At the end of the day the questioner is trying to get subject isolation. Telephotos are the best way to achieve this. When was the last time you saw a portrait with a 400mm that had a sharp background? – Matt Grum Dec 29 '10 at 10:45
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What you are after is a lack of DoF. Get close (as close as you can without making the subject look weird), use aperture-priority or manual exposure and keep the lens as wide-open as possible (clearly, you're somewhat limited here by the maximum aperture of your lens) and try to keep some distance between your subject and the background.

The field depth at any given aperture increases with the distance to the subject, so getting as close as you can without creating an unnatural perspective is key.

EDIT: I should add here that the maximum aperture of your lens changes with the focal length as well -- it's significantly wider at the wide-angle end of its range than it is at the telephoto end. That adds to the "get closer" advice.

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    this is contrary to the logic (at least to me) of peole using a focal length of 100+ to zoom in on people and get a nice DOF effect. if i understand you correct i need to zoom out and get in close to my subject with max perture? ... just saw your edit, so im correct in my asumption here then... or am i? – kacalapy Dec 22 '10 at 20:45
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    I don't know how many different ways there are to say this: DoF is a function of distance and aperture, not focal length. The only reason why there is apparently shallower DoF at longer focal lengths is the magnification factor of the finished image. Using Tech Pan (which out-resolves just about any lens so you can enlarge to the same final subject size), you can prove it to yourself if you wish. With approximately the same framing (obviously the relationships will be different), a shorter lens used closer at the same aperture will provide a shallower DoF. – user2719 Dec 22 '10 at 22:33
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    Not when the magnification is the same. I've shot everything from a Pentax 110 SLR to a Cambo Legend 8x10, and I can tell you that grain (and sharpness loss from enlargement) is the only difference between two photographs shot from the same distance with the same aperture. The reason, again, for the apparent difference at say, 50 and 100mm on a 35mm-format camera is that a 2x enlargement is done at exposure, so the bokeh artifacts will appear to be 2x larger. Getting closer will change not just the size of the bokeh, but the rapidity with which they increase fore and aft of the plane of focus. – user2719 Dec 23 '10 at 1:20
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    @Stan Remember that your f-stop is a relative aperture, and that the absolute aperture is what really affects DoF. Divide focal length by f-stop to get your absolute aperture. Many P+S cameras have a max aperture of f/2.8 (where f = 4mm, absolute aperture = 1.4mm), but your DoF is going to be much more restricted on a 55mm f/5.6 (absolute aperture = 10mm), despite the "smaller" relative aperture. – Evan Krall Dec 23 '10 at 2:20
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    @jrista I'm not missing the point at all. I completely understand the point, however I'm afraid the numbers don't add up. Using the gear posted in the original question, if you begin by shooting at 105mm and your subject is 23 meters away at f/5.6 your DOF will be 11.4 meters. Now zooming out to 18mm, opening up to f/3.5 in order to keep the same framing, you'll have to move closer, to 4 meters. Plug the numbers into your favourite DOF calculator and you get 20 meters, i.e. depth of field has increased. Using a wide lens really is the worst thing to do if you want to minimise DOF. – Matt Grum Oct 12 '12 at 12:50
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Yes, shoot at 100mm f/5.6, get close to your subject, ensure you have nothing behind your subject!

http://www.dofmaster.com/dofjs.html

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If you want a shallow depth of field, you can increase the aperture width. The easiest way to do this is to switch to aperture priority mode (A on the dial) and set the largest available aperture (smallest f-number).

Like others have said, there are other factors as well, such as subject distance and focal length, but often you have less control over those, since they affect the framing of the shot. If you are able, you will get the shallowest depth of field by increasing focal length and aperture size, and decreasing the distance to your subject.

  • see comment below, im confused – kacalapy Dec 22 '10 at 20:46
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    Wider aperture does get you a shallow depth of field, but with this lens you'll have a shallower depth of field at 100mm @ f/5.6 than at 18mm @ f/3.5 – Alex Black Dec 22 '10 at 21:36

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