How to measure distance to subject in Depth of Field calculator?

Question

I used Depth of field calculator here.

I should specify subject distance.

How to measure distance to subject?

In theory this is a distance to front principal plane or point. What is in practice?

I tried to calculate expected image size and then made shot with camera. In calculation I measured the subject distance from front lens of photo lens. This result that "theory image" about 1.5 times larger then "practical image".

Asked by sergdev

Answer

According to the FAQ for the particular calculator you're using, the calculations are performed for a thin lens, and hence the front nodal point of the lens should be used. The author recommends using the front surface of the lens, on the assumption that the front nodal point is somewhere inside the lens, and this assumption will yield a conservative estimate of the DoF.

By the way, note that in lens specifications, focusing distances are specified from the film/sensor plane. This location is often marked with a special symbol on the camera body. So these measurements are not exactly comparable to what the DoF calculator uses.

Answered by coneslayer

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What advantages does the Brenizer method have over Photoshop blur?

Question

I have seen a lot of posts lately about the Brenizer method. It looks smashing, but at the same time, I am fairly certain I could recreate the look using blurred layers in Photoshop. Apart from having a high-resolution picture using Brenizer's technique, are there other advantages I'm missing from just taking one wide-angle shot and manipulating it in PS to mimic the look?

Asked by Heather Walters

Answer

Most techniques that are 'properly' accomplished in-camera, but can also be approximated in software, are generally better in-camera. No software filter can replicate the quality of bokeh afforded by a good-quality lens (although Photoshop's Lens Blur filter does a decent job).

Having said that, the Brenizer method is relatively time consuming, both in the field and in the computer, and requires a fast lens, so whether or not you do it 'properly' or with straightforward blurring really depends on what you're doing with it. If you're just taking a family portrait shot, you may as well 'cheat'. If you're taking a shot for your portfolio or for a professional wedding shoot, it's worth going the whole hog.

Answered by ElendilTheTall

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Brenizer method vs Photoshop blur

Question

I have seen a lot of posts lately about the Brenizer method. It looks smashing, but at the same time, I am fairly certain I could recreate the look using blurred layers in Photoshop. Apart from having a high-resolution picture using Brenizer's technique, are there other advantages I'm missing from just taking one wide-angle shot and manipulating it in PS to mimic the look?

Asked by Heather Walters

Answer

Most techniques that are 'properly' accomplished in-camera, but can also be approximated in software, are generally better in-camera. No software filter can replicate the quality of bokeh afforded by a good-quality lens (although Photoshop's Lens Blur filter does a decent job).

Having said that, the Brenizer method is relatively time consuming, both in the field and in the computer, and requires a fast lens, so whether or not you do it 'properly' or with straightforward blurring really depends on what you're doing with it. If you're just taking a family portrait shot, you may as well 'cheat'. If you're taking a shot for your portfolio or for a professional wedding shoot, it's worth going the whole hog.

Answered by ElendilTheTall

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How does a teleconverter affect depth of field?

Question

I'm aware that a teleconverter will reduce the amount of light reaching the film or sensor in a camera, and as such you hear people banding around things like "With a 2x teleconverter this 300mm f/2.8 becomes a 600mm f/5.6".

Given the aperture isn't physically any different, I wonder how that affects depth of field (and associated effects like bokeh). It would make sense that the depth of field remains the same, and the image is merely cropped.

Is it just another one of these things that people say, that may be convenient for exposure calculations, or is there actually a change in the image produced?

Asked by Rowland Shaw

Answer

TL;DR version: Teleconverters don't affect depth of field at any given distance. They literally transform your 300 f/2.8 lens into a 600 f/5.6 lens. Any 600 f/5.6 lens, teleconverted or not, will have the same depth of field as a 300 f/2.8 lens.

There's a lot of confusion about the relationship between depth of field, aperture, f-stop, and focal length. In reality, it's all very simple:

Depth of field is determined by focal distance and the apparent size of the front element of the lens.

By apparent diameter, I mean the width of the area of the front element that isn't blocked by the aperture.

You can actually see how big this apparent diameter is, by looking at the front of a lens while it's detached and the aperture is held open.

The relationship between f-stop, focal length, and apparent lens diameter is as follows:

(Size of aperture in mm) = (Focal length in mm) ÷ (f-stop)

For example:

• The apparent diameter of a 210mm lens set to f/4.5 is 47mm,
• The apparent diameter of a 70mm lens set to f/4.5 is 15.5mm,
• The apparent diameter of a 70mm lens set to f/8 is 8.75mm,
• And the apparent diameter of an 18mm lens set to f/3.5 is a paltry 5.1mm.

Now, back to depth of field. Depth of field is the distance in front of and behind the focused distance that is still "acceptably" in focus. Since the level of acceptable blur differs from person to person, a better way to analyze depth of field is through the circle of confusion.

Here's a handy picture from the Wikipedia page on Circle of Confusion:

The circle of confusion is the area on the sensor that is hit by light from a single point. If you're in front of or behind the plane of focus, then your circle of confusion gets bigger. At the plane of focus, the circle of confusion is (ideally, but never in practice) zero.

How quickly your circle of confusion grows as you move away from the plane of focus is a factor of one thing only: The angle between the widest converging lines (the edge of your apparent lens size). Now, this means a few things:

• If you are focused 10 times further away, you have to go roughly 10 times further from the plane of focus to get the same change in your circle of confusion
• Two lenses focused at the same distance, with the same apparent size, will result in the same change in your circle of confusion (and therefore the same depth of field.)

Conversely, this also debunks several commonly held beliefs about depth of field:

• Two lenses at the same f-stop do not necessarily have the same depth of field. The longer lens will have a shorter depth of field, because it has a bigger apparent size. (Sorry, Matt.)
• Teleconverters, cropping, and smaller sensors do not have any effect on depth of field at a given apparent size (f-stop and focal length).

Take two pictures: one with a 35mm f/1.8, and one with a 210mm f/11. Now, crop the 35mm image to have the same field of view as the other image. They will have almost exactly the same depth of field. Here you go:

Answered by Evan Krall

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How do I get adequate depth of field in macro photography?

Question

I have been messing around with some Macro Photography using the techniques (and a reversal ring) described in a blog post by @ElendilTheTall My main issue is that I am having a hard time getting the subject into focus. There are times when the center is blurred and the outside is in focus or the center in focus and the outside out of focus. What are ways to get as much of the subject in focus?

I am using a Nikon D5100, I have a 18-55mm kit lens but I find the 55-200mm lens easier to use for shooting.

Asked by Lynda

Answer

That is part of the art and difficulty of macro photography. As with all lenses, only one plane is in perfect focus and everything closer and further will be blurry.

The only thing to do to maximize depth-of-field in one shot is to pick a small aperture. It is recommended to use something up to the diffraction limit of your camera which should be about F/16, otherwise the whole frame becomes blurry.

Once you have a certain depth-of-field, you should take advantage of it by placing the focus somewhere in the middle (as measured in sensor-distance) of what you want to appear sharp. The common rule of thumb is that depth-of-field is 1/3 in front and 2/3 in back of the place of focus.

The other option you have it to take multiple shots and merge them together using a technique called Focus Stacking. Each shot should be taken at the same aperture but with a different point in focus. There are specialized software to do that (just search for the term) but Exposure Fusion software also do it (because of how they work).

Answered by Itai

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What are “Depth of field and focus scales”?

Question

I'm reading Kurt Munger's review of SAL75300 (Sony's 75-300mm F/4.5-5.6 lens) and I noticed the entry "Depth of field and focus scales? Nothing" in his summary table. Now, I know what depth of field is but the term "focus scales" is entirely new to me. Incidentally, this is the first lens I'm hoping to buy after getting my camera body with its kit lens.

I searched for the term and from what I gather, this table entry basically says that the lens doesn't have this measure/knob/dial. I'm sorry but I'm really confused about this.

How will this (missing?) lens feature affect me as a photographer? Am I correct in thinking that this won't have a bearing on what I can shoot with this lens (or the pictures I'll get with this lens) but on how I shoot with this lens?

Asked by skytreader

Answer

It's mostly useful for film shooters, who had to get the depth of field correct before the shot, because it could be days or months before they saw the result. It's also a convenient way to get the hyperfocal distance for the lens at any given aperture without having to carry any tables with you or do any calculations while you're out in the field. With that big LCD on the back of your camera it's less important for you: just take the picture, zoom in on the preview, and if parts of the image are too sharp or not sharp enough adjust your aperture and take another picture.

So here's an old(er than me) 135mm lens with a focus scale. You can see that it's set at f/16 (the aperture ring is rotated so the dot is above the '16'). The '16' is in magenta, which corresponds to the magenta distance marks on the focus scale. The lens is currently focused to about 9m / 30ft. But the depth of field scale's near and far marks are at 7m and about 12m: so that would be the depth of field if I took a picture with it right now.

The green marks in the depth of field scale are for focusing at f/8, since '8' is in green, and of course the yellow marks show the depth of field when the lens is set to f/22. (The little red dot is the infrared focus point, another useful bit of information for some people and completely irrelevant for everyone else.)

If you don't need it, you don't need it. I've never used it (on this or any other of my manual focus lenses that have depth of field scales). For some people it's really important, but if you're primarily shooting digital you can ignore it. It's just like everything else in that table, like the number of aperture blades or whether or not the filter ring rotates: it's important to some people, but not everyone; a reviewer writes for his audience so this reviewer must think that some of his audience needs their lenses to have depth of field scales.

Here's one more example: focused like this, at f/16 everything from about 2m to infinity is in focus (in other words: the hyperfocal distance for this lens at f/16 is a shade under 2m, and the hyperfocal distance at f/16 can be achieved by focusing to just past 3m) on this 50mm lens, but at f/4 only objects from about 3-5m away would be in focus.

Answered by drewbenn

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How do I keep both the background and foreground in the image in focus at the same time?

Question

How do you have both the background and foreground in the image in focus at the same time?

Last week I was attempting a shot where I had the back of a hat in focus and in the distance you could see a mountain. I wanted both in focus, but could either focus on the mountain or the hat. I ended up taking the in-focus shots of both and merging them in Photoshop. While that isn't difficult I would prefer to shoot the shot as accurate as possible. From what I have read aperture is important in the depth of field but what are the techniques for keeping both the background and foreground in focus?

I am using a Nikon D5100 with a 18-55mm f/3.5-5.6 (standard kit lens) and a 55-200mm f/4.5-5.6.

This question almost answers my question, but I am a bit confused. Can someone explain this a bit differently? Thanks!

Asked by Lynda

Answer

I think this is mostly answered, but I'll add some examples.

When a lens is focused at a particular distance, the image will appear sharp from some distance in front of the focus point to some distance behind it. The range from "nearest sharp point" to "most distant sharp point" is called depth of field (DOF).

Here's a Wikipedia example. The focus point is the "depth of field" text, and the DOF extends approximately from the line below to the line above:

DOF depends on three factors. (That is, three factors you can easily change. DOF also depends on the size of the camera sensor, how large you want to print or display the picture, how closely you look and how critical you are, but I'll assume that these are constant.)

The factors you can easily change are

• Aperture: Smaller aperture gives more DOF.
  Example: (All examples for Nikon D5100 or other APS-C 1.5x crop camera.)
  55mm f/5.6, focus at 10 feet: DOF range from 9 to 11 feet (2 feet total)
  55mm f/22, focus at 10 feet: DOF range from 7 to 18 feet (11 feet total)

• Distance: More distance from camera to focus point gives more DOF.
  Example:
  55mm f/5.6, focus at 10 feet: DOF range 9 - 11 feet (2 feet total)
  55mm f/5.6, focus at 20 feet: DOF range 16 - 26 feet (10 feet total)

• Focal length: Shorter focal length gives more DOF.
  Example:
  55mm f/5.6, focus at 10 feet: DOF range 9 - 11 feet
  18mm f/5.6, focus at 10 feet: DOF range 5 feet to infinity

So to maximize the depth of field, the basics are

• Shortest possible focal length
• Smallest possible aperture (although at very small apertures you run into diffraction blur instead)
• If possible, increase distance between camera and foreground
• Focus slightly behind the foreground subject, to exploit the fact that DOF extends some distance in front of the focus point.

Examples:

• 18mm f/22, focus at 2 feet: DOF range from 1 to 12 feet
• 18mm f/22, focus at 10 feet: DOF range from 2 feet to infinity
• 18mm f/22, focus at infinity (the mountains): DOF range from ~2.5 feet to infinity.

So you could have everything from 2 feet to infinity in focus, by focusing at 10 feet.

If you want to go advanced, you could improve DOF slightly by focusing at what's called the hyperfocal distance. (Although you would need a table or calculator to look it up.)

Focusing at the hyperfocal distance gives the maximum possible depth of field, in this case that's

• 18mm f/32, focus at 1.7 feet (hyperfocal distance): DOF range from 0.9 feet to infinity

That's the best optics can give you. If you need more than that, you'll have to fake it by taking multiple shots and merging them.

---

You can find these values from an online DOF calculator like the one ElendilTheTall linked to. Just select your camera (or another camera with the same size sensor, like D5000 in your case) and fill in focal length, f-stop and focus distance.

Note that these DOF values are only approximate: The DOF range is calculated using a definition of "acceptable sharpness" - subjects at the edges of the DOF range will be slightly out of focus, but we might still call them "acceptably sharp" - and what you consider acceptable will probably differ from the standard definition.
You will have to experiment to find your own limits, but a DOF calculator is a good starting point.

Answered by j-g-faustus

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Why does using a tilt-shift lens make things look miniature?

Question

This question isn't so much about how to achieve the effect of making a scene look like it's modelled in miniature, but why tilting the focal plane creates the effect. What is it about photographing miniatures that makes them look like miniatures, and how is this replicated by tilting the focal plane?

I can understand how when photographing a model of a scene, you have a much higher magnification, which leads to a shallower depth of field compared to when capturing the real-sized scene, but how does tilting the focal plane help? Is it just that you have the focal plane tilted relative to the plane that most of your subject is on, so that you can achieve a narrower depth of field for the focal length and aperture, or is there more to it than that?

Asked by Edd

Answer

The reason tilt-shift "sells" the miniature effect to the eye is that it allows both the foreground and background to be out of focus. We are accustomed to seeing images of city scenes, for example, where the foreground is a bit blurry, or the distant background is out of focus, but not both. Normal lenses shooting these scenes near infinity focus will have enough depth of field that you wouldn't have a situation where both foreground and background are strongly out of focus.

When photographing real miniatures, you are focusing much closer so have much narrower DOF, so you do get background and foreground out of focus.

I believe the tilt-shift lens achieves this effect because it creates a plane of focus that is not parallel to the sensor, so it exaggerates out of focus areas. I believe you can further limit the DOF by focusing closer then using the tilt to move the in-focus area to your subject. So a combination of closer focus and stretching the plane of focus so that less of it coincides with the sensor.

Answered by MikeW

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Is there a 'rule of thumb' that I can use to estimate depth of field while shooting?

Question

I can use a DoF calculator, or crunch the heavy math by hand if I really want to know exactly what my DoF is going to be... but most of the time knowing exactly is actually overkill, and taking the time to pull out a DoF calculator is impractical. I'm wondering if anyone knows of a 'rule of thumb' that is common for quickly figuring out a rough estimate of what my DoF will be when I'm in the field...

Asked by Jay Lance Photography

Answer

Depth of field formulas are indeed complex and nonlinear, but they still afford useful rules of thumb. For medium subject distances (not too close to the lens, compared to its focal length, and not so far away that the DoF extends to infinity), the DoF is approximately proportional to:

• The f-stop.

• The square of the distance.

• The inverse square of the lens's focal length.

This assumes a given standard of blurriness (usually quantified as the diameter of the circle of confusion), which depends on your sensor, intended magnification of the ultimate images, your visual acuity, and many other things. For this reason I'm not going to recommend one rule for everyone, but rather will explain how to develop your own rule(s) for your own purposes.

To make this aproximation work, you only need to know the DoF for a standard f-stop, a standard distance, and a standard lens, chosen in advance by you. For instance, let's set the diameter of the circle of confusion to 0.02 mm (a fairly small size, but not uncommon). Then, using an online DoF calculator, we obtain a depth of field of 1.59 m = 5.2 feet for a subject at 10 meters from a 100 mm lens at f/4. Using only these data (10m, 100mm, f/4, 5.2 ft), we can now anticipate the DoF for any similar exposure combination by making a series of simple adjustments. For example,

• Doubling the f-stop from f/4 to f/8 should double the DoF from 5.2 to 10.4 feet. (Actual value: 10.66 feet.) Halving the f-stop from f/4 to f/2 should halve the DoF from 5.2 to 2.6 feet. (Actual value: 2.59 feet.)

• Now, continuing from f/2, halving the subject distance to 5 meters should divide the DoF by four, giving 2.6/4 = 0.65 feet. (Actual value: 0.66 feet.)

• Halving the lens's focal length from 100 mm to 50 mm should quadruple the DoF. Continuing from the previous result, it should go from 0.65 ft back to 2.6 feet. (Actual value: 2.62 feet.)

In this example we have worked out the DoF at 5 meters for a 50 mm lens at f/2 using simple multiplications and divisions and we have made only an inconsequential error of less than 1% in our estimate.

Thus, if you choose a standard combination of focal length, f-stop, and subject distance close to those about which you are usually concerned, you need only memorize a single DoF value which you can rescale as appropriate in the field.

Typically, you might work out the DoF for a trial shot and then use this rule of thumb to anticipate the effects of proposed changes (of distance to subject, aperture, and even choice of lens) on the DoF. This needn't even involve a calculation. For example, after examining an initial shot closely, you might decide you need twice the depth of field (even though you don't know exactly, as a number, what the current DoF really is). Your options therefore include:

• Double the f-stop. (Watch out, though, for diffraction blurring once the aperture gets smaller than a few millimeters!)

• Move back from the subject to increase its distance to the lens by about 40% (1.4^2 = 2 more or less).

• Use a lens of about 0.7 times the focal length (0.7^2 = 1/2 more or less). E.g., change from a 50 mm to a 35 mm lens.

Although the first option is so quick you might forgo any calculation and just try it, the next two could be sufficiently cumbersome or time-consuming that having this rule of thumb might just be useful ;-).

Note that the approximation breaks down for macro photography and landscape photography. In both cases one usually has more time to prepare and test shots so perhaps having a quick rule of thumb is less important in those situations.

Answered by whuber

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In what kind of scenes does it make sense to use f/1.4 aperture?

Question

I have been told that it is difficult to focus with an aperture of f/1.4.

So, in which kind of scenes does it actually make sense to use the f/1.4?

In portraits they say that it is important to keep focus on both eyes (ruling off f/1.4).
In moving subjects (street photography) it s simply not possible to focus with f/1.4.
In food photos it will then focus only a particle of food.

What are the PRACTICAL uses of f/1.4?

Asked by Anisha Kaul

Answer

There's several practical cases here. Your depth of field isn't only a function of the aperture so if other factors suite, then its still fine.

If you're sufficiently far away from your subject, then using f/1.4 would result the majority of your subject being in focus.

If you have a high performance AF system (something like the 7D perhaps), then you're more likely to keep the point of focus exactly where you expect.

If the scene is so dark, you may need to shoot at a wide open 1.4 in order to get enough light - you're willing to trade extreme subject isolation and possibly not get the exact point of focus for noise and proper exposure.

You do see it in portraits some. Its a very trendy thing to do to. The eyes should be roughly on the same focal plane, so you should be able to get them in focus and the ears will be blurred out.

Frankly though, I don't - nor do most people I know - use f/1.4 all that often.

Answered by rfusca

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How can I achieve this effect, where the flower is sharp and everything else is blurry?

Question

I was wondering how it is possible to take a picture like this.

Please have a look here for some example pictures. The flower is sharp, and everything else looks like taken with a long shutter.

Is that even possible, or do you think it's Photoshop-edited?

I asked the photographer about the lens, and it's a Minolta RF Rokkor 250mm f5.6.

Answer

Looks like it's been shot with a wide aperture (low f number, like f/2.8), from a close distance, with a camera that has a large sensor -- the combined effect is a shallow depth of field, as demonstrated there.

To reproduce, put your camera in aperture priority mode (Av on a lot of cameras) and choose a wide aperture (head for f/2.8 rather than f/22) and get shooting.

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What Budget DSLR has bracketing modes?

Question

I need recommendations on entry level budget DSLRs with plenty of bracketing modes (exposure, F-stops, etc for HDR and DOF shots). I am in Germany and am willing to spend upto €600. The brand doesn't matter to me. Also want to know if there are programmable bracketing modes available in entry level DSLRs.

Answer

The Pentax K-r is currently at €598 with the two-lens (18-55mm and 50-200mm) kit, and it includes a basic automatic bracketing mode, which will take three shots with different exposure. It also has an automatic in-camera HDR mode (also with three images), and a multi-exposure mode which automatically overlays the 3 with a simple blend.

You can choose how many stops to vary the exposure by, and what order (underexposed first, then regular, then overexposed, or another way) you want them in.

However, if you want more shots than 3, or if you want to vary something other than exposure (or choose which exposure parameter is varied), I don't think you'll be able to get it without spending more. (The twice-as-pricey Pentax K-5 has a lot more options.)

Depending on your needs, you might be best served by a non-dSLR camera — specifically, a Canon point-and-shoot model running the CHDK firmware hack, which could give you very powerful programmatic control over bracketing. With your budget, you could go for the high-end P&S Canon G12, which is listed as supported by a beta version of CHDK. (Models change all the time, of course; if you come back to this question a year from now, make sure to see what's latest.)

Or, you can, of course, simply bracket manually.

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Why doesn't the background become blurred when I change the aperture on my Fujifilm S4000?

Question

I am sorry if my question is too naive, but I am a complete beginner in photography, and I think I still need to understand well what aperture is. I have a Fujifilm S4000 camera, and I know I can't do with it everything that a professional camera does.

I wanted the background of some pictures to be blurred by changing the aperture, but I don't get the results I expected. I think it also has to do with the focal length, am I right? I took two pictures to show you what I mean.

Picture 1 Aperture: f/4 Exposure: 1/2 s Focal length: 7 mm

Picture 2 Aperture: f/10 Exposure: 2.6 s Focal length: 7 mm

I would like to know what settings I can use to get the background to be blurred. I know that with smaller aperture values, the area around the object in focus will be more blurred, but when I change from f/4 to f/10, it doesn't change much.

Answer

There is NO different at ALL because the physical aperture has not changed.

The Fuji Finepix S4000 simulates a small aperture using an ND filter. When you stop-down, the ND filter slides into the optical path. The Aperture written i the EXIF is adjusted to reflect the transmittance of the ND filter but since the size of the opening has not changed, Depth-Of-Field does not change either.

Not only do such cameras have very small sensors and extensive depth-of-field but they are also extremely prone to diffraction. If the aperture was actually stopped down to F/10, images would get quite blurry.

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Why doesn't the background become blurred when I change the aperture?

Question

I am sorry if my question is too naive, but I am a complete beginner in photography, and I think I still need to understand well what aperture is. I have a Fujifilm S4000 camera, and I know I can't do with it everything that a professional camera does.

I wanted the background of some pictures to be blurred by changing the aperture, but I don't get the results I expected. I think it also has to do with the focal length, am I right? I took two pictures to show you what I mean.

Picture 1 Aperture: f/4 Exposure: 1/2 s Focal length: 7 mm

Picture 2 Aperture: f/10 Exposure: 2.6 s Focal length: 7 mm

I would like to know what settings I can use to get the background to be blurred. I know that with smaller aperture values, the area around the object in focus will be more blurred, but when I change from f/4 to f/10, it doesn't change much.

Answer

There is NO different at ALL because the physical aperture has not changed.

The Fuji Finepix S4000 simulates a small aperture using an ND filter. When you stop-down, the ND filter slides into the optical path. The Aperture written i the EXIF is adjusted to reflect the transmittance of the ND filter but since the size of the opening has not changed, Depth-Of-Field does not change either.

Not only do such cameras have very small sensors and extensive depth-of-field but they are also extremely prone to diffraction. If the aperture was actually stopped down to F/10, images would get quite blurry.

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What are the “Distance Setting Marks” for use in storytelling composition?

Question

I am reading Understanding Exposure, by Bryan Peterson, to learn some bits and tricks about photography.

I came across one line "You would first choose to set your aperture to f/22 and than align the distance above your distnace-setting mark on the lens."

I am very much clear that for landscape/story telling compositions I need to have maximum depth of field, so I understand being asked to set aperture as f/22, but I'm not sure what "align the distance above your distance-setting mark on the lens" means?

I am using Nikon D-90 with its 18-105mm kit lens. Doing some googling showed that such a type of scale was only available on the old lenses and is no longer in use.

Can any one help me to understand what does this means, and how I can achieve this when my lens doesn't appear to have such a scale?

Answer

You're right, many modern lenses don't have a distance scale window. There's two reasons for this. Well, three, if you count extreme cost-cutting. But primarily:

• Most people use auto-focusing most or all of the time. Having a distance scale is less interesting.
• Lenses designed to be optimized for quick auto-focus have little "throw". That means the focus ring doesn't move very much when going from near focus all the way out to infinity. This makes auto-focus faster, since there's less for the motor to move. Lenses designed with manal-focus in mind have a longer throw, allowing more careful by-hand adjustments.

But it's not true that distance scales are obsolete. Many (most?) high-end lenses have a scale like this, as do quite a few lower-end or moderate lenses (like the Nikon 18-200mm superzoom. So, if you're willing to go beyond the kit lens, there's that option.

You don't really need this to do "storytelling" composition, though. You can use autofocus on something midway into the scene and be assured that with large depth of field, it'll be close enough. I think part of the point of this particular style is that you don't want to have to worry about it too much. You can also practice a bit with your lens, observing how and where it turns to focus to infinity and close up, and learn to judge the right middle position without the scale. (Be aware, though, that modern lenses usually focus beyond infinity, so turning all the way to the end will actually make far away things less sharp.)

(As an aside, I object to Peterson's use of "storytelling" for this particular style of photograph. It's absolutely right that this can be used for a certain kind of storytelling image, but, I don't think the label should be reserved for it. Just a few minutes ago I saw a blog entry from Kirk Tuck where he posted about an older photo he took with a large aperture. This shows a young boy responding to large, soft, warm raindrops. The whole scene is emphatically not in focus, yet it tells way more of a story than some random bridge at a small aperture. Basically, Bryan Peterson is okay, but I'm not fond of his labels. He tends to go for something catchy-sounding without a lot of reflection on whether it's really the best way to explain something.)

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How do you use the Depth of Field Preview button on a Nikon D90?

Question

I am trying my hands around using Depth of field preview button with my Nikon D90 and its 18-105mm Kit lens. I read some online material as well have seen some videos about using it, but so far I'm not having any luck.

I've tried the following:

1. First i set my aperture to 5.6,focused on some object 5-6 feet away adjusted the light meter and than pressed the DOF button.
2. Again changed the aperture to 11 with same steps than to 22 with same steps.

I don't see any changes when I do that, though. Now this means either I am really dumb (:)) or i am missing something. Can any one help me figure this out?

Answer

I hate to say this, but first make sure you're pressing the right button, as I always press the wrong one. There are two similar buttons. One is the function button near the top of the lens, and the DOF preview button is almost under the lens.

If you press the DOF button, even with the aperture wide open, it will make a very clunky sound, like when you press the shutter and the mirror bounces up.

At f/22 the image through the viewfinder should get much darker.

I'm pretty certain you can't reprogram that button on the D90.

Edit: picture worth 1000 words! This is a D80, but button is in the same position (from digitalreview.ca)

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What is the depth-of-field preview button on my DSLR supposed to show me?

Question

I'm fairly new to DSLRs and I've been exploring the functions on my new Canon 60D.

There's a button to the side of the lens described as the "depth-of-field preview button". Based on the limited description in the manual, I thought this would give me a preview of how the photo would look in terms of what's in and out of focus when I'm using Live View.

When I press it though, despite jerking as if it's processing something, I see no difference in the LCD screen. I've played with the aperture with no discernible effect.

Am I missing something? What should I be seeing?

Answer

DoF preview is difficult to use well. The idea is simple, but application much less so. Without DoF preview, what you see through the viewfinder is shown with the lens "wide open" -- at its largest possible aperture. This provides no guidance about how much depth of field your picture will have, because (unless you happen to be shooting at maximum aperture) the picture you're seeing in the viewfinder won't be at the same aperture as the picture you take.

In theory, DoF preview is a simple answer to that: it just closes the aperture on the lens to whatever aperture you have set for the picture. If, for example, you were going to take a picture at f/11 using an f/2.8 lens, the DoF preview will stop the lens down from f/2.8 to f/11.

Difficulty in application stems from two facts. First of all, stopping the lens down significantly makes the view through the viewfinder darker. Second, and more importantly, the focus screen on most current cameras doesn't portray depth of field very accurately. A focus screen that transmits more light directly through gives a brighter view. Since most people depend on autofocus for focusing and don't worry much about DoF, this is the sort of screen used in most current cameras. A screen can be built to diffuse the light more. This doesn't give as bright of a view, but also makes the apparent sharpness in the viewfinder drop off much more quickly when things are out of focus. This makes the DoF preview in most cameras pretty inaccurate. What you see in the viewfinder will show a lot more DoF than the real picture regardless of the exact aperture the lens is set to.

As such, to use DoF preview at all well, you just about have to do some testing to compare what you see in the viewfinder to what you get in the picture. The two won't be the same (usually, anyway), and it's up to you to train your eye to compensate for the different between what you see and what you'll get to be able to compensate.

One technique I've used with reasonable success is to take some pictures at a particular aperture (e.g., f/8) and set up a laptop screen next to the camera so you can quickly look from the viewfinder to a picture you just took. You can then adjust the aperture (with DoF preview) to get close to the same DoF through the viewfinder as shows in the picture. What you really care about is how much difference you see between the two. Let's say the viewfinder at f/3.5 shows roughly the same DoF as the picture on the laptop that you took at f/8. That gives a difference of roughly 2.5 stops. From then on, you can use DoF preview to adjust the zone of sharpness as you see fit, and know that you'll need to open the aperture ~2.5 stops from there to get about the same DoF when you take a picture.

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How can I get bokeh with an aperture of 3.5 as my max?

Question

I am trying to get DOF portraits of my daughter with my Nikon d7000, as per my previous post.

I have zoomed in to 100mm or so and tried to get a large aperture but as I zoom, the camera decreases f# to about 6.

I have also tried in aperture priority mode and still have the same problem lowering the f#.

What am I doing wrong?

Answer

You can't zoom to f/3.5 at 100mm on your lens, your lens will do at best f/5.6 at 105mm.

You can however get a shallow DOF effect quite easily, for example by shooting at f/5.6 at 105mm, with your subject quite close (say 6ft) and you background say 10ft behind the subject.

See this set of photos I took with a Nikon D70 (much older predecessor to the D7000!)

You can see the shot at f/2.8 has a shallower depth of field than at f/5.6, but at f/5.6 you can clearly see the subject in focus and the background blurred, you can even see that at f/8. (They aren't all sharp, I was on a tripod, long exposures, and caused the camera to move when I released the shutter, i used a 5s timer after that..!)

At f/5.6 at 200mm the effect is even more pronounced.

I'm sure at f/5.6 at 105mm you could do even better than I did, getting closer to the subject, and having the background further away.

f/2.8, 105mm

f/5.6, 105mm

f/8, 105mm

f/5.6, 200mm

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Can you help me justify my desire to purchase the Nikkor 24-70mm f/2.8 even though I find it rather pricey?

Question

I have a D70 with the stock Nikkor AF-S 18-70mm f/3.5-4.5G ED DX lens. I'm about to replace the body with a D7000. I've found the 3.5 f-stop a little limiting in terms of DoF - and having viewed some photos from a friend with an f/2.8 lens am keen to get something that goes to this aperture/speed. Is the Nikkor 24-70mm f/2.8 G AF-S ED the lens to go for? I mostly shoot my family in and outdoors and am really looking for some nice upclose head and sholder shots taken while kids play etc (i.e. not posed). Should I go wider, e.g. 17-55mm f/2.8 G DX AF-S IF-ED? Later I'd also be interested in the 70-200mm f2.8 G AF-S VR IF ED II zoom - which of the previous 2 would this go best with? Are there any cheeper alternatives to these lenses (which are pretty pricey...)?

Edit: I should have mentioned that I have a Nikkor 50mm f/1.8 AF prime that takes great shots - the issue here is that because I'm shooting my family in action (kids at play, parties etc) I really need the flexibily of a zoom. A prime maybe OK if say everyone sitting round a table but when kids are moving, running round and playing you just can't move fast enough to keep up and frame a good shot with a prime (well I can't).

UPDATE: I ended up dropping a whole lot of cash on a Nikkor 24-70mm f/2.8 G AF-S ED - which I don't regret for an instant. This lens is beautiful and once the shots start rolling in, you quickly understand that a good lens is priceless. I would greatly encourage anyone new to digital photography to put money in the lens and NOT in the body - i.e. I think you'd be better off with a second hand $150 D70 + a great lens rather than a modern body that cost $1000+ but which will be worth $100 in 2 years. In 10 years your $1400 lens will likely be worth around $1400...

UPDATE: StuckinCustoms has this basic review of the Nikkor 24-70 lens with some nice sample shots (althought they are all HDR - but if you ignor that you they still give a good feel for the Dof and zoom range of this lens.

Answer

The Nikkor 24-70mm f2.8 G AF-S ED is a superb piece of kit, and priced accordingly. If your livelihood isn't dependant on getting absolutely optimal quality every time, you could consider a third-party alternative.

I use a Sigma 24-70mm f/2.8 Macro lens that's good enough 99% of the time, and costs less than half the price of the Nikon version. You should check that a third-party lens works with the D7000 before buying one. I've heard of incompatibilities between third-party lenses and cameras that didn't exist when they were produced but I don't know if there's any truth in that.

The 70-200mm f2.8 G AF-S VR IF ED II is the natural partner to the Nikkor 24-70mm f2.8 G AF-S ED because one picks up where the others focal length ends. It's probably one of the most common configuration in a pros kit bag (along with a wide angle and probably a 50mm prime, just in case).

If you use the the 18-24 range of your current lens in your existing photos, you might consider another lens. That's up to you.

Personally, I don't want to carry a 0.9 kg lens around with me all the time. If I were you, I'd go for a Nikon 50mm f1.8 D AF. It'll give you high quality images for a fraction of the price assuming you don't mind "zooming with your feet". That's what I use 90% of the time when I know I'm shooting people at a modest distance. Spend some of what you've saved on an SB-700 flash, which will give you far more flexibility.

If you find you need a bit wider (group shots or indoors?), there's a Nikon 35mm f/1.8. If you need to shoot from further away (sports, or just less distracting?), there's a Nikon 85mm f/1.8. Those will all work better in low light, and you can buy the whole lot for less than a Nikkor 24-70mm. You lose the ability to go from one length to the other in a twist of the lens, but you probably know in advance what length you'll be shooting at in a given circumstance. You save money and (more importantly) carrying weight.

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Is it possible to take shallow depth of field photos with point-and-shoot cameras?

Question

I have an Olympus 770SW compact digital camera, and in macro mode I can manage to achieve a blurred background, if the background is far enough away (over a metre). Can this be done when taking non-macro pictures, and if not, is there a way to simulate it?

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Merged: How to blur the background using a super-zoom camera?

When I shoot portraits with my brother's Nikon D90, this is quite easy to fade out the background. But with my Fuji HS10, super-zoom camera, I haven't been able to take such photos yet. I choose a large aperture for my camera but it still doesn't work. I know that standing further and zooming will result in a smaller depth of field. Why DSLR cameras are so much better in this area? Why zooming make the depth of field smaller? What are the general recommendations to do the job using a super-zoom?

-- Moshen

Answer

There's a good answer from Brian Auer, which I'll reproduce here, as it pretty much covers the problem you're trying to solve:

Ooh, good question. Yes, but how much will depend on the camera.

If the camera has manual controls for aperture, that definitely helps. It also helps if the camera has zoom, as most P&S cameras do. The problem with creating a shallow depth of field comes from the fact that the sensor is so small, and as a result the lens is close to the sensor — thus creating very small focal lengths. My P&S has a focal length range from 6mm to 18mm — which is very small. They create an effective focal length much higher due to the small sensor size. As I said in the tips, a short focal length will produce an image with nearly everything in focus.

So to blur the background using a P&S, you’ll get your best results if you zoom in all the way, focus on something close (you don’t want to focus out to infinity), and have a background that is much further away. So your two points of control are focal length and subject distance. I just gave it a shot with my camera, and it does work.

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