Depth of Field and the Importance Distance to Subject Plays

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Let’s say that perhaps you’ve been taking photos for a while now. You’ve gotten yourself a good DSLR camera and have recognized that the standard 18-55mm kit lens that comes with your camera is nice, but just doesn’t give you the shots that you are looking for.

IMG

So you plunk down your money on the ever-popular 50mm f/1.8 prime lens that everybody is talking about, mount in on your camera, change your aperture to its widest (f/1.8) setting and start shooting. You spend all day shooting with this wonderful little lens and then you get home and put them on your computer and realize that 80% of your shots are out of focus.

In the past, when this used to happen to me, I would reason that shooting wide open was just not possible, because I ended up with too many shots that were out of focus. I incorrectly reasoned that I always needed to close down my aperture when shooting portrait subjects, or they would end up out of focus because the shallow depth of field was just too unusable wide open. For a while, I only used my 50mm 1.8 lens at f/4 because it was the widest aperture that I trusted to get the shot in focus. Crazy yes, I know. But then I figured out something that has changed my use of wide-aperture lenses forever.

Before we continue, let’s break down the meaning of “wide open” and “fast prime lenses”. To shoot “wide open” means that you are choosing to photograph at your lens’ widest aperture setting or f-stop. On a lot of lenses, the widest aperture is listed somewhere on the lens itself with Canon usually listing it on the front of the lens, and Nikon listing this information on the body of the lens. Generally the ration looks something like this: 1:2.8 or 1:1.8. (See photos)

IMG 4418 IMG 4419

A “fast prime lens” is one that has one focal length (does not zoom) and has “fast” light-gathering ability (due to its wider apertures). Most photographers consider a fast lens to be one with an aperture number of f/2.8 or wider (the smaller the number, the wider the aperture). Two of the most popular features of fast prime lenses are their ability to obtain beautiful out of focus backgrounds and shallow depth of field, as well as their ability to handle low-light conditions because of the aforementioned large apertures.

Let me let you in on a little secret about shooting wide open – it’s about the distance to your subject. Most people learn that wide-aperture lenses blur the background and let in more light, but they never understand that the really neat shallow depth of field created by their lens is also affected by another factor; how close they are to the subject.

You won’t find many manuals on subject to camera distance. It’s kind of an assumed topic that doesn’t get enough attention. Let’s look at it as simply as possible: the closer you are to your subject, the shallower the depth of field is relative to your chosen aperture. In other words, if you are shooting at f/1.8 and you are 20 feet away from your subject, you will have MORE depth of field than you will if you are shooting 2 feet away from your subject.

To get more mathematical, if you’re using a 50mm lens at f/1.8 and photographing something at 4 feet, your depth of field will be around 1.5 inches deep. But if you photograph that same subject from 10 feet, you will have a depth of field of just under 10 inches deep.

2ft 35mmP

Shot at 2ft with a 35mm lens at f/1.4.

9ft 35mmP

Shot at 9ft with a 35mm lens at f/1.4. 

The right image cropped to similar framing as the left. Notice the increase in depth of field on the hair and ears, and also the reduction in lens distortion.

2ft 35mm

Shot at 2 ft with a 35mm lens at f/1.4.

9ft 35mm

Shot at 9ft with a 35mm lens at f/1.4. Cropped to similar framing. Notice how the pencils in the back row come into focus.

With this information, it is also very important that you get to really know your lens and its abilities. For instance, if you happen to know that you shoot a lot of portraiture close to your subjects, be aware of how much depth of field your lens gives you at three feet, four feet, and so on, when shooting wide open. In time, with experience, you will be able to immediately predict the depth of field your lens will give you based on the distance you are away from your subject.

5ft 85mmP

Shot at 5ft with an 85mm lens at f/1.4.

12ft 85mmP

Shot at 12ft with an 85mm lens at f/1.4.

The depth of field does increase slightly in the right image, but not as dramatically as the 35mm lens due to the 85mm longer focal length.

In conclusion, you can see that the reason your photos might be coming out blurry would be because of your distance to your subject when shooting wide open. So the next time you find yourself frustrated at your results shooting with that wide-aperture lens at its widest aperture, take a step or two back. You might like the results.

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Al Jurina is a part-time photographer,full-time teacher living in Harrisburg, Pennsylvania. He has been teaching high-school photography courses for over 7 years and has owned his own portrait and wedding photography business with his wife since 2009. You can see more of his portrait work on his website and on his tumblr blog here.

  • rebecca haegele

    Thanks!

  • Michael G.

    Great article!!!

  • Michael O

    I own a 50mm prime at 1.8 and barely use it as intended. I’ll definitely have to utilise it more as I do love the out of focus areas that add a sense of depth to shots. I usually do that with foreground or BG blur using my telephoto a distance away from my subject.

    Time to get intimate with 50mm I guess hehe

  • Tim Lowe

    Yeah, but… The comparisons with the same focal length at different distances involve cropping. I shoot primarily 120 (6×6) film and never crop for obvious reasons. Isn’t the lesson here, use the right lens for the effect you want?

  • Al

    I agree with you, but some people can get so caught up with the concept of “the right lens” that they never learn to use the lens that they have. I would have never taken many photos shot wide open if I felt that my 50 1.8 was not the right lens. The examples are cropped simply to show DOF differences. It should not be assumed that you’d just step back and crop all of the time to get the right DOF.

  • Doug Sundseth

    “Notice … the reduction in lens distortion.”

    What you’re seeing is perspective distortion, not lens distortion. Regardless of focal length (assuming you can get that crop), any lens shot from that distance will show the same distortion.

    The ability to shoot tight without cropping and with very limited perspective distortion is one of the primary reasons people like long lenses for portraits.

  • Tim Lowe

    All true. I shoot mostly an old Hasselblad 500. I got 50mm, 80mm, 150mm and 250mm. That’s it. And they are WAY too heavy to put more than two in the bag. Have to plan ahead. 😉

  • Al

    Right. Whether the distortion is from the lens or the perspective, it’s usually not pleasing for close-up portraits. Some people will argue that even 50mm lenses are not flattering for close up portraits. I’ve even heard seasoned professionals knock 70mm. They will say 85mm or higher for tight shots. It all comes back to knowing your equipment and the shot you want.

  • Michael

    Thank you much! Your article is very informative and helps people who can’t afford to buy fast long lenses for portraits like me. I own 3 lenses, the kit Canon 17 – 85 mm f/4 – 5.6, the telephoto Canon 55 – 250 mm f/4 – 5.6 and recently bought the Prime Canon 50 mm f/1.8 II. I use the prime lens mostly indoor allowing me to use almost wide-open aperture for portraits and also having these DOF problems in f/1.8 to 2.8 range. So I have been trying to limit the aperture to no more than 3.2 or above because I did not realized to step back another few feet. I do not mind to crop my photos and still get right focusing and DOF still having blur backgrounds.

  • Interesting article but I think the title is misleading, and reminds me of an argument I had with a Director of Photography when I was focus pulling for him many years ago.
    He was insistent that just going further away from a subject, then shooting on a longer lens, would result in a shallower depth of field. I tried to explain to him that all he was doing was compressing his FIELD OF VIEW (which gave the impression of a shallower DEPTH OF FIELD) but he was a DoP and was having none of it.
    Only when we had gone from a 50mm lens 25 feet from the actor to a 500mm lens 250 feet from the actor was I able to demonstrate to the DoP that both shot sizes had the same depth of field (in this case about 5 foot at F 2).
    As many of your readers will know, there is a direct relationship between lens size, aperture size, and distance to the subject in relation to Depth of Field (or how much of your image will be in focus). Increase any of these independently of the others and you will get a shallower depth of field, decrease them and you will increase your depth of field. But when you adjust more than one (e.g. : increase lens size AND increase the distance to subject) there is no difference to the depth of field.
    What you seem to have done in your article is to further confuse the subject by adding cropping in post. Perhaps you should have called it “how to increase the percentage of useable pictures when shooting wide open (by stepping back and then using cropping in post)”.
    On that basis, another way to increase the number of keepers is to crank up your ISO so you can stop down on the iris a little.
    Also, it would have been helpful if you had shot your images against something other than a plain background, as there is no indication of the different FIELD OF VIEW that you get from cropping the picture, or from using a longer lens.
    My advice to your readers is to experiment with different focal lengths to see which they like and then practice getting it sharp wide open, or using higher ISO to be able to stop down before reverting to cropping the images in post.

  • Awesome article! You pretty much capture my worries about using the 50mm lens. Now back to practice!

  • Angela

    Al, I need to do a group photo of about 40 people stacked about 3 deep. My biggest concern is getting everybody in a nice sharp focus. The 2 lenses that I have are the Nikon kit 18-105mm f/3.5 – 5.6 and a Sigma 18-250mm f/3.5 – 6.3. Which would be the better lens to use and do you have any other suggestions to get the sharpest focus possible using either of the lenses?

  • Al

    I’d say that either lens will get you something decent. Try to avoid a tight crop though at 18mm as the people on the edges will look distorted. In other words, leave some space on both sides of the group at the outer edges of the frame.

    As for aperture, I’d shoot f8 or f11 and focus on the middle row of people. For large groups, I try to make everybody close their eyes, count to 3 and then tell everyone to open them. Then take a burst shot of 3-5 frames. That trick has helped me with large groups for quite a while. Good luck!

  • Al

    I see what you are saying but I disagree with some of your resolutions. The goal of the article is to give people courage to shoot wide open. Increasing ISO to stop down their aperture to get more depth of field kind of defeats the point of using a lens at 1.8. If I could sum up what I wanted to say in the article in one sentence it would be: “When shooting wide open on your lens, be careful of your distance to the subject”.

    When I shot exclusively with my 50mm 1.8, it was because it was the only lens that I had owned. I wanted the shallow DOF, and putting another lens on was not an option.

  • Angela

    Thank you! I appreciate your advice and your article. I just got a new Nikon D3200 and I’m very excited to see the differences from my Nikon D90. I think my photos will be crisper.

  • If the goal of the article is to give people confidence to shoot wide open then I definitely suggest you change the title to reflect that.
    And if you can sum up the article in one sentence, which you did, then that should be the title.
    Don’t get me wrong, what you suggest is a useful tip, but the net result (increasing the distance between you and the subject) has exactly the same affect as stopping down the iris – it just increases the depth of field.
    Also, it just doesn’t follow on from the headline, hence my suggestion that it is misleading.
    Depth of Field is a complex subject. Adding cropping to the mix just overcomplicates it further, not to mention the resolution that you lose by doing so. I know we live in a world of 50MP + sensors, but understanding the basics goes a long way to making us all better photographers.

  • I totally agree with you when you say that people get hung up about having the perfect lens.
    Most ‘fast’ lenses (even the expensive ones) suffer from chromatic aberration, distortion and vignetting when shot wide open.
    It is generally agreed that (almost) all lenses are at their best at between F 5.6 and F 8. – learn the lenses that you have, rather than buying an expensive replacement, and you’ll be amazed at what you can achieve with a kit lens, when you know how to use it.

  • Al

    I see your point. I my own defense, I had changed the title to “what nobody tells you about shooting wide open” and had revised the article somewhat with less images but it looks like the older version was published.

  • That’s a much better title and totally describes the body of the text.
    More photos are always a good thing. As I say it would have been nice to see some out of focus backgrounds rather than just the plain backgrounds.
    Please don’t think I’m just trolling your article – it’s a good starting point for a discussion,and thanks for your input.
    I hope to read more articles from you in the future.

  • Bruno Henrique

    Ótimas dicas. Obrigado por compartilhar seus conhecimentos.

  • kartikjayaraman

    How do you deal with the less DOF problem with video, especially when using FF. If you step away, cropping severely reduces quality on 1080p footage

  • ken

    Forgive my ignorance, but when you crop, how do you resize without losing image quality? Everytime I shoot from a greater distance and crop the image stretches and is pixelated. Again, forgive my ignorance, but any help you can provide would be appreciated.

  • Al

    Video is a different beast. I don’t think that I would necessarily be applying this technique to video for the reason that you just mentioned. Using shallow DOF is a neat effect in video, but I’ve read a few places where people are beginning to gather the idea of it being a somewhat trendy tool that is overused. That being said, I’m not much of a video guy so I’m not much help in this area. Good question though.

  • Al

    I think that it depends on the extent of your cropping and with which tools. I do most of my cropping with adobe photoshop and Lightroom.

    I don’t ever shoot shallow DOF with the purpose of cropping after the fact to get a closer look. I hope that my article didn’t insinuate that.

  • Guest

    How are you able to crop the images when you are shooting further away from the subject and not lose resolution? Sorry for the ignorance, but any advice would be great! Thanks,

  • krodoff

    I guess what I’m saying is that if I take a portrait, like the examples, from 2ft and 9ft, I use the crop tool on the 9ft photo and then when I complete the crop, the image ‘stretches’ and look pixelated. I know this is rookie territory, but I’m just frustrated. I have Photoshop CS6 available to me.

  • Al

    You always lose resolution when you crop, because you are, in essence, throwing away pixels. The images in my example are kept small so that the loss of quality isn’t so apparent. The best advice that I can give for this is to try your best to get it right in the camera, so that you have less need to crop.

  • I really enjoyed this. thank you.

  • Stephen Longoria

    hey, I used to have that same lens (17-85 also) sold it along w/my entire camera just to upgrade to full frame and it’s great, came with 24-105, also have the 1.4 prime for those low lighting areas,,,,,,,,,,,,,,,all work great.

  • Mike Burchard

    I have always found it simplest to explain DoF as a function of aperture and relative image size, e.g., if a same subject is framed as to occupy precisely the same 50% of a given composition in two different images, and one of those images is taken with a 35mm @ f/2 while the other is taken with an 85mm @ f/2, although the perspective will be significantly different, the DoF will be the same.

    Just my two cents.

  • DookOffURL

    Hey Gregg, I understood what he meant just fine. I found your comment poorly written and more confusing than the article by a magnitude of 10. Talk about your DoP’s

  • Gordon Orser

    Great article. I’m trying to better understand the relationship between aperture and focal length, distance to subject and how this all ties together. What you have written here is a great help. Question I have is how the actual lens opening changes at different focal lengths. For instance f10 at 100mm/200mm/300mm, the lens opening would be 10mm/20mm/30mm respectively, do I have this right? What really confuses me is what happens, for instance, with my 300mm lens at f5.6, the opening can’t possibly be 54mm. Not sure if I have this right and hopefully I don’t confuse anyone if I don’t.

  • CrysMarie

    It’s annoying every time someone gets all picky about choice of title. If you prefer a different one, write your own post. I found this article in no way at all to be misleading because of the given title. If it was helpful to you, great! If not, unless the author is giving faulty harmful advice, just move along!

  • “if you’re using a 50mm lens at f/1.8 and photographing something at 4 feet, your depth of field will be around 1.5 inches deep” — too many different units! If you’re using metric (“50mm lens”) please stick to it…

  • I’m a novice who doesn’t do much portraits. I get what your saying regarding getting more depth of field by backing up, but what about framing? I can step back to get more depth of field and then crop later, or I can stay close to the subject and close the aperture to get more depth of field. Which is better?

  • Josh

    A good DOF calculator will help people understand this concept with distance to focus point and how it affects DOF. I use DOF Calc on my droid.

  • hemo2

    I suspect the answer is, “It depends”. To ‘fill the frame’, if you have plenty of resolution and can crop the image to get the framing effect you want, then back up and shoot at f/1.8 and crop it in post processing. But honestly, if you want to fill your frame, what’s the point of backing up for the purpose of getting extra depth of field & having to crop later, when you can get similar results by simply stopping your aperture down and fill the frame when you take the shot? I personally would not shoot at f/1.8 very close to the subject and instead stop down my aperture a stop or two and stay close to fill the frame. Being close to the subject, my background is still going to be fairly blurred shooting at f/2.8 or even f/4 (depending on my focal length) but my subject will have that bit of extra depth of field for their face. For most standard portraits, if you have a backdrop, blurring the background isn’t a concern, but generally the person you shoot is going to want their face (specifically their eyes) to be “in focus”!
    FYI – Three things affect Depth of Field. Aperture, Focal Length, and Distance to Subject. I almost always use aperture and focal length to control my depth of field and it’s very rare that I use distance to control it.

  • nicolemorris

    thanks so much for writting about this. im getting really frustrated at the moment as im using a 50mm and my photos keep coming out blury. they arnt as sharp as i want them to be.
    im going to be reading this article over and over so it sinks into my brain

  • Ashley

    Very helpful; thank you!! One question… I’m not great at math, so I’m struggling to figure out what the exact math is to figure out how far you should stand from your subject. Would you mind explaining the math part? Thanks!

  • Hannah Christine Govan

    Some people have gone to great lengths to flaw-pick this article. I’m not sure why. I am an amateur photographer so not every article on DPS interests me. It was the title that made me click on this one and I found it very useful. Photography can be an extremely complicated topic if you let it. I’m all for simple explanations that help you get your head around a topic, even if there might be a few holes in it. Might I add that if this article had been written to the specifications set out below by Gregg, I probably wouldn’t have finished it. Well done!

  • Great article! Thanks

    Follow me at jaxchile.tumblr.com
    My experiences through photography in the true deep south… South America.

  • ledmikew

    Pretty annoying that this website overrides user agent preference in mobile browsers so that I can’t compare the photos of the boy side by side as they are meant to be seen and compared and contrasted. Is the sites design aesthetic worth more than the sites usability?

  • Jere Miah

    “Increase any of these independently of the others and you will get a shallower depth of field, decrease them and you will increase your depth of field.” – This is incorrect – increasing the distance to your focal point will increase your depth of field, not make it shallower.

  • K.G.W.Abeytunge

    Is taking a step or two back equal to reducing one or two stops (using a smaller aperture) because if you are close to the subject the depth of field would be still good enough to put the background out of focus and keep the subject sharp?

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