Tag Archives: depth of field

Reader Questions, Technique

Reader Question: About Depth of Field

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Lupine, Upper Sabrina Basin
Lupine, Upper Sabrina Basin

I recently received an email from David, who has some questions about depth of field:

As you have a lot of experience of using the Fuji X-E1, may I please ask you for some advice regarding landscape focusing.

My aim is to use the 18-55mm kit lens with the majority of shots taken at the widest end. I have in mind setting the lens at Hyperfocal distances, based on a crop factor of 1.5 and a circle of confusion of 0.02. I think the first figure is reliable, but I’m not sure about the second in relation to the X-E1 – perhaps you could confirm.

I have already done some testing at home using the attached table (which come from the well respected DOFmaster site).

In my experiment I carefully measured distances at apertures of f8 and f11 using a tripod and a printed card as the subject. I set the lens manually at the hyperfocal distance, using the EVF distance scale. I was disappointed to find that the closest point of focus was not as sharp as I had hoped. Have you any idea why this may be?

I did a further test on aperture f11 and this time set the distance scale at 4 feet (2/3 of the way between 3 and 5 feet). This resulted in a sharp image from 3.5 feet. This would suggest that the distance scale is not accurate.

Any suggestions you have to overcome the problem would be much appreciated.

Let me preface my response on the depth of field (DOF) issue by congratulating you for taking the time to conduct your own experiments. One of the great things about digital cameras is that we don’t have to trust what we read — we can easily and quickly conduct the experiments ourselves. In addition to getting the answer to the question at hand, we end up knowing our gear at a much deeper and even intuitive level, which is extremely important when we are in the field and we don’t have time to ponder and calculate, but must instead make a photograph in the moment.

The rest of this post is going to be somewhat involved, so let me share a quick thought right at the beginning:

The usefulness of DOF calculators is very limited, as they are based on subjective assumptions that may not match what you are doing with your photographs. The best way to align your expectations with exposure choices is to test them yourself and evaluate images in the form that you most often produce — and not just at 100% magnification on a computer screen.

What is DOF? Essentially the depth of field is the distance range in front of and behind (unless you focus at infinity) the focus point within which subjects are likely to sharp enough to seem in focus when the photograph is viewed at some arbitrary magnification. This size of this range increases as we stop down (for example, going from f/2.8 to f/8 expands the DOF) and decreases as we open the aperture (going from f/8 to f/2.8 contracts DOF). This is a source of creative control for the photographer. A smaller aperture can allow subjects across a greater distance range to appear relatively sharp, while a larger aperture can keep the primary subject in focus while pleasingly “un-focusing” elements in front of and behind the primary focus point. Continue reading Reader Question: About Depth of Field →

Morning Musings, Technique

Making Aperture Selection Easy (Morning Musing for 8/22/14)

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From time to time I see questions from photographers trying to figure out exactly which aperture is the “right” one for a particular photograph. Some will go so far as to consult depth of field calculators (or “DOF calculators”) to help them decide whether the should open up a third of a stop from f/11.

There may be times where that sort of precision aperture selection is useful, but in many cases you can make things a lot simpler*, basically selecting from one of three general options:

  1. If depth of field isn’t a big issue — let’s say you are shooting a relatively flat subject — simply use a “middle of the road” aperture that will be sharp on your lens/camera combination. The old rule of thumb about using f/8 is a decent one to follow here, although cropped sensor shooters might go for something more like f/5.6.
  2. If you need very deep depth of field, go straight to the smallest aperture you feel comfortable using. On a full frame camera this is likely to be about f/16, while on a cropped sensor camera it might be a bit larger, perhaps in the f/11 or so range. If your need for extra deep depth of field is strong enough that you are willing to give up a small degree of overall image sharpness — which will be invisible in small images anyway —  you might even go one stop smaller on some occasions to f/22 on full frame and f/16 on crop.
  3. If you need to limit depth of field to throw background elements out of focus, simply try the largest aperture that your lens has — but consider stopping down just a bit if you need just a bit more depth of field.

Basically, for most photographs, especially if you have good light and/or are using a tripod, you could probably get away with considering only three apertures in most cases — the “normal” one, the really small one, and the really big one.

  • Yes, this is a bit of a simplification, though it really does work in the vast majority of the photographs that most people are making. Clearly things can get a bit more complicated if you are, for example, shooting in very low light or need to deal with moving subjects. In the interest of keeping this “Easy” description easy, I’ll simply acknowledge those possibilities here without elaborating.

G Dan Mitchell is a California photographer and visual opportunist whose subjects include the Pacific coast, redwood forests, central California oak/grasslands, the Sierra Nevada, California deserts, urban landscapes, night photography, and more.
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Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

Equipment, Technique

Some Thoughts on Aperture and DOF and Related Issues

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(This post is slightly adapted from something I recently posted in a photography forum in which hyperfocal distance, “DOF calculation” software, and related issues were under discussion.)

Shooting as a way to learn to understand how things like depth of field or “hyperfocal distance” work is a great idea – it is perhaps the best way to understand these concepts. I firmly believe that it is better than relying on tools such as software DOF (“depth of field”) calculators or tables. Fortunately, it is easy to do some basic experiments related to aperture and DOF and the so-called hyperfocal distance.

(The term hyperfocal distance can be interpreted in a couple of ways. In photography, this is often thought of as the distance at which you might focus in order to place objects at different distances in focus. If there is an object that is 15 feet from the camera and there are important subjects at infinity, the hyperfocal distance lies beyond the object that is 15 feet away and closer than the far away objects that might be in focus with the lens set to “infinity.”)

To find out about the effect of aperture on DOF, try the following:

  1. Put the camera on a tripod and compose some reasonable test image that includes subjects at various distances from the camera position, with a primary subject somewhere between the closest and the furthest.
  2. Focus on your primary subject within the scene.
  3. Shoot a series of images at apertures ranging from the largest to perhaps f/16 – shoot at f/1.4, f/2, f/2.8, etc. You might want to go as far as f/22 on full frame.*
  4. If you want to be a bit more methodical, you can use your DOF tables/software to “calculate” your hyperfocal distance, focus there, and repeat the process – but, frankly, I wouldn’t bother.
  5. Spend some time – likely well under an hour – looking over the results on your computer. If possible, make a few small prints to confirm the relevance (or not) of what you observe on the screen.

Another great way to understand the effect of aperture on the depth of field in your shot is to shoot in live view mode on your DSLR. Here you can press the DOF preview button, zoom in the live view display to 5x or 10x magnification, and pan around the magnified image on the rear display to see a very good approximation of the effect of your aperture choice on elements of the scene at various distances from the camera.

SIMPLIFICATION: A SECRET

Let me share a little secret. From reading some photography forum posts, you might get the idea that lots of photographers are going around making careful and technical calculations of precise hyperfocal distance and DOF and all the rest and then making exactingly accurate choices about aperture for each shot. In general, it doesn’t work that way in the real world, where photographers often tend to select aperture in basically three ways:

  1. In a shot where the subject doesn’t have a lot of depth and DOF isn’t really an issue, we tend to shoot at some default aperture that we believe is more or less optimal for overall resolution, corner resolution, and perhaps vignetting. On full frame, this might frequently be roughly f/8, though there are reasons to vary from that a bit sometimes.
  2. When working a subject on which we want very large DOF, we tend to go straight to the smallest aperture that we feel will produce large DOF and very good resolution. For me, this is typically f/16 on full frame, it might be no smaller than f/11 on cropped sensor cameras. There are situations in which I might use a smaller aperture, but they are very rare and will involve acceptance of some tradeoffs.
  3. When faced with a shot in which we want very narrow DOF, we tend to open up as much as we think we can, perhaps tending toward the largest aperture on the lens we are using. There are some additional factors to consider here, but I’ll leave them out for now in the spirit of simplifying.

So, a simple generalized approach:

  • Shoot at some middle-of-the-road aperture when DOF isn’t a major concern.
  • Shoot at the smallest acceptable aperture when you want large DOF – f/16 on full-frame or f/8-f/11 on crop.
  • Open way up when you want to minimize DOF.

This approach works in a wide range of real-world photographic situations, and it is especially useful to begin with it when you have to work quickly. There will be situations in which these are simply starting points, and you’ll need to make some modifications – for example, in very low light you might not be able to use that very small aperture if you are shooting hand-held, or your largest aperture might produce DOF that is too narrow for some subjects, and so on. But starting with this simple basic concept, using live view DOF preview when appropriate, and learning from experience will likely move you a lot further along on the road towards understanding and making effective use of aperture/DOF than trying to rely on some DOF calculator. (Depite their appearance of accuracy, these calculators depend on a bunch of assumptions that may not match up with your photography.)

* You can stop down further on cameras with larger sensors before you run into issues with diffraction blur, a softening of the overall image that occurs with the smallest apertures. To generalize, while you can stop down to roughly f/16 on a full frame and still produce very sharp images, you might want to avoid such a small aperture on your cropped sensor DSLR, perhaps avoiding anything smaller than about f/11… and you might want to be a bit cautious about using f/11.

© Copyright 2012 G Dan Mitchell – all rights reserved.

G Dan Mitchell is a California photographer whose subjects include the Pacific coast, redwood forests, central California oak/grasslands, the Sierra Nevada, California deserts, urban landscapes, night photography, and more.
Blog | About | Flickr | Twitter | Facebook | Google+ | 500px.com | LinkedIn | Email

Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

Equipment, Ideas, Photographic Myths and Platitudes, Technique

Photographic Myths and Platitudes – ‘Landscape Photography Lenses’ (Part I)

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(NOTES: This article has been updated periodically since its original publication, including a more significant update in 2019. And, yes, there is a Part II.)

A recent discussion got me thinking once again about another “myth” of landscape photography, namely that [i]some lenses are appropriate for landscape photography and other lenses are not[/i]. There are several such myths, including but not limited to the following aspects: focal lengths, zooms versus primes, maximum apertures, expense, etc. While I could have a lot of fun (or not!) starting with the zoom/prime question, I have saved that for Part II. (Short preview: I think that “zooms or primes?” may be the wrong question, the image quality implications are not as simple as you might think, and I use both… but tend more and more to rely on zooms.)

Instead, I’ll start with…

Focal Length

The trigger for this was a discussion of the suitability of a certain type of lens for landscape photography. I had made a point concerning a 85mm prime that I sometimes used, and the other party disagreed with my perspective. Several rebuttals to my thinking were offered, but the one offered as a sort of trump card was that using a 85mm lens for landscape is an inappropriate choice, and one should use a wide-angle zoom like a 16-35mm lens.

While many landscape photographers know better, especially those who have done this for a while, it is surprising how many folks assume it to be accepted wisdom that proper landscape photography is done with ultra-wide to perhaps normal focal length lenses, and that the first and perhaps only lens that a landscape photographer would want would be such a lens. (Again, I’m not getting into the prime v. zoom question here – I’ll save that fun topic for a later post. :-)

In my view, the best answer to the “what focal length is best for landscape?” question is the focal length that works best for the photograph I am making right now. My current kit, based on full frame DSLR bodies, covers focal lengths from 16mm to 400mm — technically 560mm if I add a 1.4x TC. While I frequently work with less than the full kit (when backpacking, for example), when I’m not constrained by weight or other limitations I carry lenses to cover this full range and typically use most or all of them. What follows is an overview of some of the lenses I use, accompanied by some photographic examples and a bit of explanation. Continue reading Photographic Myths and Platitudes – ‘Landscape Photography Lenses’ (Part I) →