distance to the subject

[BratNikotin]

<p>How do I figure out the distance to the subject for a given aperture/shutter? <br>

I feel that a lot of times, I am out of focus because I choose wrong aperture/shutter for the distance to the subject.<br>

I know aperture effects depths of field, but not sure how to narrow down this seemingly simple task of positioning myself for the shot. Is there a formula? Or a technique to measure?<br>

For example, <br />A) I am photographing a subject within 3-5 feet from me, and the goal is for it to be a portrait. I know to widen my aperture as <br /> much as possible, lower the ISO, and set the shutter accordingly. No problem here.<br />B) Same but my subject is 40 feet away, and I want a mountain range in the background. I make my aperture thinner, well <br /> depending if I have a good support to lengthen the shutter more or not. <br />I understand these simple cases.<br /><br />But, suppose<br />C) On a concert, I can get close of far away from performer, and I kind of want it to have a blurry background but do want to catch some greens and blues and purple lights in front and in back of performer. Sometimes I get lucky .. but often either lights are great but face is out of focus or opposite. I get a face perfect, but the image looks boring and doesn't convey the concert dynamics.<br>

Any advise?</p>

<p>Thanks</p>

<p> </p>

[craig_shearman1]

<p>Generally speaking, aperture and shutter have nothing to do with the distance to the subject. Exposure is determined by the amount of light falling on the subject and it doesn't matter whether the camera is a foot away or a mile away.<br /><br />But I get what you're getting at.<br /><br />Making a head and shoulders shot of a person, it's common to want to keep the background from being distracting by placing it out of focus, aka "bokeh." To do this you typically use a longer focal length -- anywhere from about 85m on up on a full-frame camera -- and shoot wide open (2 or 2.8 for example). You adjust the shutter speed and, if necessary, the ISO to allow you to shoot wide open.<br /><br />For a landscape, you typically want everything in focus. So you stop down, maybe to f/16 or f/22, and again adjust the shutter speed and/or ISO as necessary. If you have say a big rock in the foreground and a mountain in the background, one trick is to set the focus point about one third of the distance to the mountain rather than focusing specifically on the rock or specifically on the mountain. It splits the difference on the depth of field so both are in focus.<br /><br />Those are both pretty simple examples. It gets trickier when things get more complicated. If you have a group of three or four people, for example, setting the lens wide open to get the background out of focus might mean that only one of the people is in focus and the others are out of focus. In that case you have to arrange the pose so they are closer together and/or stop down the lens to a smaller aperture for more depth of field.<br /><br />(Depth of field is the range of distances that are in focus when focused on a specific distance. You get less of it at wide apertures and more when stopped down. With a 50mm "normal" lens at f/16 and focused on 15-20 feet you might get everything from five feet to infinity in focus.)<br /><br />Distance from camera to subject affects depth of field -- the closer you are the less depth of field. Longer lenses have less depth of field. There are also correlations between focal length and distance that affect depth of field that I don't know well enough to cite but I know them when I see them. :)<br /><br />As for your concert example, there are simply times when you can't get everything in focus. You have to choose one or the other, and it's up to you which is most important. 99 times out of 100, it's the person's face that is most important, most specifically their eyes. And if you have to choose, it's the eye closest to the camera that is considered the most important. Keep the eyes in focus and most people won't complain about the rest.</p>

[Jochen_S]

<p>Why would you want colorful lights in focus when you shoot a concert?<br>

If you want blurry background from a distance you need a bulky and expensive fast long lens. faster shutterspeeds to handhold it and higher ISO to gain them. <br>

I don't know what kind of camera you are using and how you set focus. Do you keep it on auto everything?(<- bad idea) Or select the AF spot by hand?<br>

When I focus on a performer's face I get it in focus on a good day. AFAIK many cameras tend to have their best i.e. most sensitive in low light AF spot in the center and the surrounding ones are worse, so selecting that one and reframing before you shoot might make sense. - I don't understand:</p>

<blockquote>

<p>I feel that a lot of times, I am out of focus because I choose wrong aperture/shutter for the distance to the subject.</p>

</blockquote>

<p>IMHO its a huge contradiction to:</p>

<blockquote>

<p>photographing a subject within 3-5 feet from me, and the goal is for it to be a portrait. I know to widen my aperture as much as possible, lower the ISO, and set the shutter accordingly.<strong> No problem here.</strong></p>

</blockquote>

<p>When I shoot a portrait at that distance with a wide open lens I am in precision focusing hell. - Crunch your numbers through a DOF calculator like <br>

http://www.dofmaster.com/dofjs.html <br>

At 5ft I get less than 1" DOF in total with my 90mm at f2 at f5.6 I#d get 3" which are either more forgiving or enough to get nosetip & rear eye sharp. <br>

Under real world conditions (assuming my camera to be a tad front or back focusing and / or me and the subject moving a bit from or towards each other while I am reframing) I'd rather stick to medium apertures with enough light at hand than go for focusing spray & pray.<br>

Anyhow if you can do ordinary portraits wide open succesfully; whats the issue with musicians on stage?<br>

One thought: might you be using way too long shutterspeeds and IS / VR so you are getting motion blurr while they are jumping around?</p>

[Spearhead]

<p>For concerts, focus on the face only. In most venues with a lot of colored lighting, there isn't going to be enough lighting, so you shoot wide open at the highest ISO you can tolerate. The lights should do their own thing, it's not clear what kind of results you are getting that are "boring." Maybe you should post a photo that has this problem. It's also not clear why you want lights in front of the performer.</p>

<p>This was shot wide open (f2.8), ISO 6400, and 1/60. Fortunately, I was close enough to not need to crop and shot this at 32mm. The face is in focus, the lights are there too. Nothing else needed to be done.</p>

 

<center><img src="https://farm4.staticflickr.com/3775/13858438303_433dd5b133_z.jpg" alt="" width="595" height="397" />

<p><em>Goat</em></p>

</center>

[Matt Laur]

<p>Great Goat shot there, Jeff.<br /><br />The linked-to DoF calculator is a good way to do some thought experiments, and to see the inter-relationships between distance, aperture, and focal length. <br /><br />None of those things have anything to do with you getting what want in focus to be in focus, though. That's just care in focusing. But those other variables will impact how much <em>else</em> is in focus (in front of, and behind the thing on which you're actually focused).</p>

[Renee Shipley]

<p>Dima, I'm glad you asked this because I have had this same question myself but struggled to word it!</p>

[dan_south]

<blockquote>

<p>A) I am photographing a subject within 3-5 feet from me, and the goal is for it to be a portrait. I know to widen my aperture as <br />much as possible, lower the ISO, and set the shutter accordingly. No problem here.<br />B) Same but my subject is 40 feet away, and I want a mountain range in the background. I make my aperture thinner, well <br />depending if I have a good support to lengthen the shutter more or not. <br />I understand these simple cases.</p>

</blockquote>

<p> <br>

What if the subject is five feet away, but you want to see what's behind it. Would you still shoot with a wide open aperture (e.g. f/2.8)?<br>

<br>

What if you wanted those distant mountains to look blurry? Would you still shoot with a small aperture (e.g. f/16)?<br>

<br>

The aperture (f-stop) does effect depth of field to some degree. You'll need to select the right aperture for the desired result.<br>

</p>

<p>The distance from camera-to-subject-to-background also plays an important role. If the subject is 100 feet away, you'll have more depth of field at f/8 than you will if the subject is 5 feet away.<br>

<br>

You need to decide how much or how little depth of field you need for a given image. Then decide what shutter speed you need to control movement (if any) or camera shake (if shooting hand held). <br>

<br>

The final variable is ISO. You can raise the ISO to a higher number if you need to increase your shutter speed at a given f-stop. But keep in mind that you'll sacrifice dynamic range to do so. In general, you'll want to keep ISO as low as possible as long as you are shooting fast enough to control both subject motion and camera shake.<br>

<br>

Example: Equivalent exposure values<br>

<br>

Two of these are fast enough to yield a sharp, handheld image in most situations (if the focus is accurate). Which two? In each of those two cases, what was sacrificed in order to boost the shutter speed?<br>

<br>

1/15 s @ f/16 @ ISO 100<br>

<br>

1/250 s @ f/16 @ ISO 1600<br>

<br>

1/250 s @ f/4 @ ISO 100</p>