What lens for best dof?

Discussion in 'Nikon' started by nicholas_martinson, May 29, 2010.

  1. Hi Im a noob. I have a Nikon D5000 with the kit lens (18-55mm). I was wondering what lens I should get for a much lower depth of field. I already know how to lower the dof with the lens I have but I want the background much more blurred.
     
  2. For a shallower depth of field you want a larger aperture and a longer focal length. A 600mm f4 has a really shallow depth of field, but at $10k, you might be looking for something in a lower price range like a 50mm f1.4. :)
    You have to know what focal length range you are looking at to be able to choose a lens to get that shallow depth of field.
     
  3. I agree, the 50mm 1.4 is the cheapest solution, next would be the 85mm 1.4d little pricey, but you get what you pay for here.
     
  4. Take a look at the online DOF calculator. Plug in the data for your camera, the lens you're considering, aperture, distance, and it'll give you an idea of what to expect.
     
  5. First of all, the Nikkor 50mm f/1.8 AF-D lens is the least expensive solution, and the background blur at f/1.8 is similar to that at f/1.4. However, on a Nikon D5000 the 50mm focal length may be useful for portraits, but it is often a little long. You might find that the Nikkor 35mm f/1.8 AF-S is a better choice. Personally, I'd prefer a 24mm lens on a DX body (such as the D5000). Nikon does make a 24mm f/1.4 lens, but it is extremely expensive. I don't know anything about this offering, but Sigma makes a 24mm f/1.8 lens that is less expensive. You may already know what focal length from your 18-55mm lens you most often use. If not, you may want to try ExposurePlot (http://www.cpr.demon.nl/prog_plotf.html) and analyze a set of your favorite images. If you often find yourself wanting even longer focal lengths, the 85mm f/1.8 is a less expensive way to get into very blurred backgrounds.
     
  6. It depends on what you want to shoot and a budget would be cool too. Subject to camera distance is also a very important variable in determination of dof.
     
  7. "I already know how to lower the dof with the lens I have but I want the background much more blurred."
    Hence what you need is a faster aperture lens. Keep in mind that if you look for background blur, some lenses perform more nicely than others.
     
  8. Note that the 50/1.8 and 85/1.8 lenses mentioned above will not auto-focus on the D5000. You need lenses that have built-in AF motors ("AF-S" lenses from Nikon, Sigma's "HSM" lenses, etc). Especially when you're shooting with a wide aperture to deliberately throw the background out of focus, AF accuracy is all the more important. And Jose touches on a potentially important issue: the quality of the background blur. Some lenses handle that in a more pleasing way than others (search here on the term "bokeh" for many interesting and/or maddening discussions!).

    You can use your current zoom lens to help establish a sense of what focal length is actually going to be useful to you compositionally (should you go with a fixed focal length "prime" lens). Certainly Nikon's 35/1.8, at around $200, is going to be the least expensive fast lens you can get, and that focal length leds itself well to many types of shooting ... but it might be a little too short for you, portrait-wise, if you're not doing full-length stuff. The 50/1.4 mentioned above will be a more flattering portrait length, and you could use either Nikon's newer 50/1.4 G, or Sigma's 50/1.4 HSM. I'm partial to the Sigma, specifically because it performs so well at the wide apertures you intend to use, and does a really beautiful job on the out-of-focus bits.
     
  9. This may not seem interesting, but you should also look into the lens construction.
    In order to give a smooth and creamy bokeh, you will want a lens which has around 9 circular aperture blades , like the Nikon 70-200mm f/2.8 VRII, which is potentially a good lens for DOF, and will AF with the D5000
     
  10. And for a really useless suggestion, think about a larger format. A lot of fashion and advertising work with really nice blurred backgrounds is the result of using a 2 1/4 camera like a 'Blad and an f/2.8 lens or faster, or even large format. Look at classic large format portraits- no DOF there at all. Too much never being enough, a lot of work gets blurred in Photoshop too.
     
  11. Matt makes a very important point that is worth restating:
    You will need to get a lens with
    • "AF-S" in the name (for Nikon Lenses)
    • "HSM" in the name (for Sigma lenses)
    • "Built in Motor / BIM" (for Tamron lenses),
    otherwise the lens will not autofocus on your camera. That said, some of the less expensive, very large aperture lenses that come to mind are:
    • Sigma 30mm f/1.4 EX DC HSM
    • Nikon 35mm f/1.8 AF-S DX
    • Nikon 50mm f/1.4 AF-S
    • Sigma 50mm f/1.4 EX DG HSM
    You can occasionally pick up some of these used for a lower price on Adorama, B&H or KEH. If you don't care about not having autofocus anymore and having to grab the focus ring on the front of the lens to focus manually before each shot, then any non-AF-S/HSM/BIM lens will work (such as the Nikon AF-D series).
     
  12. Somewhat OT, but: DoF is a function of aperture and image size, not focal length.
    Telephoto lenses do not have "shallow" DoF.
    Shoot a subject with a 50mm lens and then a 100mm from the same distance and the DofF is greater with the 50mm...but that's because the subject image is smaller. Move in closer with the 50 until the subject is the same size as it was with the 100 and DoF will be the same.
    btw, though the subject image size will be the same when using a 100mm lens from 10 feet or a 50mm from 5 feet, the perspective will be different. This is the flaw in "get a prime and zoom with your feet" advice.
     
  13. Telephoto lenses do not have "shallow" DoF.​
    True. But they do throw the background more out-of-focus. Hence, the longer the lens, the creamier the background.
     
  14. I highly recommend the Sigma 30mm f1.4. It will AF with your camera too.
    Kent in SD
     
  15. "But they do throw the background more out of focus."
    Nope.
    "more out of focus" is another way to say shallower depth of field.
     
  16. Joe, John is absolutely correct.
    The depth of field is defined as the range of distances over which the diameter of the blur circle is less than some "acceptable" diameter. This diameter is often taken to be some fraction of the diagonal of the sensor / film. As you point out, the depth of field is approximately independent of the FL of the lens.
    HOWEVER, as John pointed out, once your subject is outside of that range, the diameter of the blur circle increases much faster for long lenses than it does for short FL lenses. This gives the impression of substantially smoother backgrounds and greater separation of the subject from the bkgnd when using long FL lenses and is the effect most people are impressed by when they see an image taken with a 300/2.8. They are noticing how blurred the background is, not the small range of distances over which the image stays acceptably sharp. That's the important distinction between these two quantities.
    There is a good discussion of this on Wikipedia:
    http://en.wikipedia.org/wiki/Depth_of_field
    HTH,
    Tom M
     
  17. Very interesting topic. I love photography.
    As far as I know, focal lenght actually affect DoF... but I`d say it can be negligible at "normal" distances, being more evident at large focusing distances. If we calculate DoF for a macro shot, there will be no difference, but there will be a slight difference at say, 10 meters, increasing it towards infinity.
    Then I think we could say focal lenght doesn`t affect DoF in practical terms.
    About background blur, there will be more or less background area depending on the focal lenght; perspective counts here. Obviously, it will be more stuffed a wider angle, small magnificated background than, as Tom says with the 300/2.8, a highly magnificated background subject. Simply imagine that you can easily avoid light source spots e.g. in a street portrait with a tele lens, that could be inside the frame with a wider viewing angle lens. Which lens will provide a smoother looking background?
    Another topic could be the ammount of detail in that blurred areas.
     
  18. If you're thinking of portraits or macro work with insects and flowers etc., another lens not mentioned so far is Tamron's 60mm f2.0 macro lens, which has really nice creamy bokeh, and is quite sharp wide open without being too "clinical" on skin texture. Being a bit longer, it will act as if a 90mm f2.0 on an APS-C camera. That will help with portraits - I find a 50mm lens (acting as if a 75mm) still shows a bit too much distortion (slightly enlarging the nose) if I get in close to fill the frame.
     
  19. Okay, we have an obvious beginner here. How many people agree that he should just get the 35mm f1.8 from Nikon and learn from that? I mean... medium format for a noob? A 2500-dollar 70-200 for a D3000?
    I think sometimes that we who are frequenters on photo.net do "noobs" a lot of dis-service by assuming they wnt pro gear or complete complex knowledge and solutions.
    Nicholas, a 35mm f1.8 Nikkor is only 200 bucks, functions perfectly with your camera, and is capable of taking some great "narrow depth of field" shots. It is basically a "standard" lens on DX (which is what your camera is) like the 50 used to be on film (which almost everybody bought as their first lens 30 years ago). Just buy it and be deliriously happy.
     
  20. I think sometimes that we who are frequenters on photo.net do "noobs" a lot of dis-service by assuming they wnt pro gear or complete complex knowledge and solutions.​
    No, I think we should bore the "noobs" to death with all these techno circle of confusion focal length at normal distance times depth of field equals creamier bokeh stuff plus seven to circular nine aperture blades is extremely important. I mean...how else is he/she going to learn how to photograph correctly? This is not...abstract expressionism:)
     
  21. Leslie,
    LOL! You forgot the importance of hand-ground aspherical elements vs. molded or (horrors) hybrid elements. Everybody knows you can't take a picture of your dog or your kid or the flowers your husband bought you unless you understand and appreciate all that... ;-P
     
  22. 105/2.5 AI, AI'd or AIS.
     
  23. [O]nce your subject is outside of that range, the diameter of the blur circle increases much faster for long lenses than it does for short FL lenses.
    I don't think that's correct. I am with Joe on this. If you're willing to bear with me, here's an explanation: depth of field is a semi-arbitrary measure of how much blur something can have and still appear sharp. Really, only the actual infinetessimally-thin plan of focus is totally in focus. Anything in front of, or behind, it is somewhat out of focus. For practical purposes, we chose a semi-arbitrary amount of blur in the print and then derive a depth of field table for the conditions of the picture. I seem to recall that typical DoF tables have been based on print circles of confusion of 0.125 to 0.250 mm; for comparison purposes, one pixel in a 300 ppi print is 0.085mm, so we're talking a circle of confusion of about 1.5 to 3.0 pixels.
    Now it is a readily demonstrable fact that for any given camera (or more generally, sensor size or film size), only the f-stop affects depth of field. If you go from a 50mm lens to a 600mm lens, to get the same composition, you need to back up much more, which increases depth of field. In the end, if your subject is effectively flat, whether you're using a 28mm f/2.8 or a 400mm f/2.8, both wide open, if you frame the subject the same (which will of course require very different camera-to-subject distances), the depth of field will be the same.
    The suggestion that with the longer lens, the degree of being out of focus increases faster behind the subject is wrong for this reason: the depth of field calculation tells you how far away from the plan of focus something can be to be out of focus by a fixed amount--a fixed amount of blur, a circle of confusion size. You can change the circle of confusion size and get more or less calculated depth of field. But again, run the numbers and you will see that, say, for a given set of conditions, with the subject framed the same, say, a 50mm lens at f/4 and a 100mm lens at f/4 will both give apparent depth of field to +1.5 ft behind the subject (or whatever). By changing the acceptable print circle of confusion, you can see that the depth of field drops / degree of being in focus off at the same rate.
    As to using medium-format or large-format cameras to get less depth of field, that's not that much of a help. Let's take Nicholas' D5000. Suppose he goes to a 6x6 medium format camera. Let's assume with both he prints US-standard prints wit 4:5 aspect ratios (8x10, 16x20, 24x30, very nearly 11x14 inches). The 6x6 will have almost exactly three stops less depth-of-field at any given aperture, but the lenses will be at least two, oftene three, sometimes more stops slower. There are very few 6x6 lenses faster than f/2.8, and if you want anything other than a "normal" lens, your options are fewer. Suppose we want the equivalent of a 135mm lens on a 35mm camera, which I regard as a classic for tight head-shots. For the D5000, we could get a Nikon 85mm f/1.8 ($450 new). For a 6x6, the equivalent focal length would be about 250mm. For, say, Hasselblad, there's a 250mm f/5.6--which 3.3 stops slower, so at the respective maximum apertures, the 6x6 actually has a tad more depth of field. Now if we go to 4x5, we need a lens of close to 600mm, or at least 500. Even assuming the lens is a telephoto design to allow reasonably close focusing with a normal camera (at some point the bellows can't extend far enough; on my 4x5, the practical limit for non-telephoto lenses is about 360mm lenses, equivalent to about 57mm on a D5000 or 86mm on full-frame), and even taking the 500mm, you need a lens no slower than about f/11 just to stay even with that 85mm f/1.8 on the D5000. Well guess what: the lenses it the 500- and 600mm range tend to be f/9's and f/12's--in other words, maybe a hair less depth of field, but not dramatically different.
    Yeah, I suppose you can find an old 178mm f/2.5 Aero Ektar and shoot it on a 4x5, and get really shallow depth of field, assuming the equivalent of a 28mm lens on a D5000 give you the field of view you want. Or I think Schneider made an 80mm f/2 for the Rollei 6xxx medium-format SLR's. But by and large, these are not practical solutions.
    So depending on what you want it for, for practical purposes and reasonable budgets, the 35mm f/1.8, 50mm f/1.8, and 85mm f/1.8 are the worthwhile options. If the f/1.4 versions are within your budget, go for it. Moving up to full-frame will help too: an f/1.8 lens on a D700 will give you about the same minimum depth of field as a f/1.2 lens on a D5000.
     
  24. As someone who owns a D5000, I find the 50mm f1.4 AF-S lens really great for shallow DOF. Just a bit of an investment. The 35mm f1.8 being next on my list, and pretty cheap too. Sadly the 85mm lemses from Nikon will be manual focus only on that body. Hello Nikon?
     
  25. Nicholas, was any of this helpful? I'd just like to know. Sometimes photo.net can intimidate newbies. We don't want to do that, honest. So, please let us know if we're helping at all.
     
  26. Peter---
    I think he took "circle of confusion" too literally and just left:) I would like to know if it was helpful for Nicholas also.
     
  27. Peter Hawking couldn't have explained it better. After this advice, I think he smashed that D5000 on his forehead. Now he can only see with shallow DOF.
     
  28. The topic is still alive... nobody has mentioned yet a discussion about the convenience of a digital bellows camera system + adapter for selective DoF control based on the Scheimpflug`s principle... :p
     
  29. @Joe S - Thanks for posting those useful links. I had seen demos like this and was just in the process of looking for them when you posted the links to Luminous Landscape.
    @Dave R - In the 2nd link posted by Joe S, look carefully at the series of images in the section titled, "The Depth of Field is Essentially the Same". Note how the tower in the background is much larger and appears very soft in the shots taken at long focal lengths compared to shots taken at short focal lengths. In fact, in the first of the two 17 mm shots, ie, the one where the magnification (ie, size of the subject) is held constant, the tower and background buildings appear almost sharp. This is what I meant when I said that once and object is well outside the DOF range, the amount by which OOF objects are blurred is much larger (ie, its OOF image is spread out over a much larger area).
    I believe the flaw in your argument is that you are comparing the blur of the OOF objects while keeping THEIR magnification constant, not keeping the magnification of the primary subject constant and then looking at the degree of blur in the OOF objects.
    Cheers,
    Tom M.
    PS - BTW, not to add more confusion to this topic, but I noted a relatively minor error in one statement in the Luminous Landscape article -- he refers to a 1/3rd - 2/3rd rule. This is simply not so. The distances of the near and far thresholds for being OOF vary smoothly from 1:1 all the way to 1:infinity as you approach hyperfocal conditions. In addition, most DOF calculators make simplifying assumptions (eg, paraxial rays, etc.) that somewhat affect their results. Let them guide you, but don't think the value of the numbers they produce are exact.
     
  30. Here is an excellent article about the myth about 1/3 rd and 2/3rds rule:
    http://www.naturescapes.net/docs/in...two-crop-factor-magnification-and-the-13-myth
    The real answer is that the ratio changes as your focal point/hyperfocal distance changes. And there is a minimum of 1/2.
    As a practical matter if you are a long lens shooter, the actual result is more likely to be 50-50 or 1/2 in front and 1/2 behind for subjects that are close to you. This is how I discovered the myth, by looking at my out of focus beaks on birds.
    Joe Smith
     
  31. Tom Mann, you are absolutely correct that using lenses of different focal lengths will affect how wide a view of the background you get, even assuming you change the subject-to-camera distance so that the framing / magnification of the primary subject is the same.
    Also, I see what you're referring to about the DoF dropping faster. Indeed, the longer lense will make the backgroun more magnified and therefore blurrier on a per-pixel (or whatever) basis. But of course the additional magnificant also makes the details more visible. So I guess in a sense I agree with what you said, while disagreeing that this is usually a real-world useful trade-off.
    Jose Angel--true, but now we're getting really complicated! Also, whether tilting the plane of focus produces a useful practical reduction in DoF depends on the subject and surroundings. Often it works, but sometimes it produces unpleasant side effects.
    And of course, as we get more and more exotic / expensive, masking and blurring in the digital darkroom look like better and better solutions!
     
  32. Hello! Thank you everybody for responding. I learned some new things and understood most of it. Thank you Peter for being straight forward and more relevant. I bought the 35mm f1.8.
    here< is a picture I took and 'shopped it for shorter dof. Its what made me really want a new lens because I want that kinda picture soc.
    A couple of albums:
    http://www.facebook.com/album.php?aid=179971&id=733160736
    http://www.facebook.com/album.php?aid=152932&id=733160736
    What do you guys think of my pictures? Am I alright for a noob? I know I over edited some of them.
     
  33. You are good enough (for a "noob") that you probably want to learn all that esoteric "circles of confusion" stuff.
    Glad we could help!
     
  34. Nicholas: just so you know, your links take most people to a redirected Facebook login page, denying them the ability to see the images until they join or log in. Also: FB tends to really make a mess of most images (quality-wise), so when you want to share images in the context of threads like this, you might want to use Flickr or some other service that doesn't require visitors to sign up for a third-party service in order to see them. As you do more of this, and do more exploring, that issue is going to come up more often - so, time to get out in front of it. Keep at it!
     

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