What is Depth of Field

What is Depth of Field (DoF) ?

 

Depth of Field is the amount of your image before and beyond your focus point that will be in focus. Depth of field tells you whether or not your subject and background can be sharply focused at the same time.

Depth of field is determined by several factors:
* Aperture/F-Stop
* Lens
* Subject Distance

While the camera can actually only focus on one tiny point in space, the depth of field determines how much of the image is in "acceptable focus" to the human eye.

In subjects such as landscapes, a large depth of field is often desired so that the entire scene appears to be in focus. With subjects such as portraits, a small depth of field is often used to blur the background and reduce distractions from the main subject of the image.

The Effect of Aperture/F-Stop on Depth of Field :
 

Aperture describes an adjustable opening inside your camera lens that controls the amount of light striking the film. As the size of the aperture changes, the angle of light striking the film also changes. It is this angle change, much like eyeglasses change the angle of the light, that creates changes in depth of field.

Aperture is measured by F-Stop on your camera controls. F-Stop settings represent a ratio derived from the size of the lens opening and focal length. Aperture has historically been confusing for new photographers (and some established photographers) because of the apparent conflict in description. A small F-Stop is a large aperture opening and a large F-Stop is a small aperture opening. Because a smaller aperture limits the amount of light entering the lens, a large F-Stop also requires more light to properly expose an image.

A simpler way to remember the relationship between F-Stop/Aperture and Depth of Field is:
 Large F-Stop = Large Depth of Field = More Light Needed Small F-Stop = Small Depth of Field = Less Light Needed

This means that larger F-Stops, such as F11, will require slower shutter speeds and produce images with larger depths of field. Smaller F-Stops, such as F4, will allow faster shutter speeds and produce images with shallower depths of field.

The Effect of Aperture/F-Stop on Depth of Field:
 

The focal length of your lens plays a big part in determining the depth of field (DOF) for your images. Think of your lens strength as a limiting factor for your aperture capabilities. The higher the magnification factor, the smaller the depth of field will be, even with large F-Stop settings.

Depth of Field Progression for a 70-300mm Lens
* 70mm = largest DOF
* 100mm = large DOF
* 200mm = small DOF
* 300mm = smallest DOF

This effect is especially pronounced in macro photography where close proximity to the subject and high focal lengths result in depths of field that are sometimes less than an inch.

The Effect of Subject Distance on Depth of Field :
 

Much like lens strength, subject distance, plays a big part in determining the possible size of depth of field. The closer you are to your focal point, or subject, the less depth of field is possible. To illustrate this effect, hold your hand at arm's length in front of your face. Even when focusing on your hand you can probably see a good bit of the surrounding environment in reasonably clear focus. Slowly move your hand towards your face until you reach the half-way point. Notice how much less of the area surrounding your hand is in focus. Continue moving your hand towards your face until it is as close as your eyes can focus on it. Very little of the area surrounding your hand can now be seen.

This same effect occurs with your camera lens. This effect, combined with high magnification factors, results in the tiny depth of fields seen in macro photography. It also makes the huge depths of field in many expansive landscapes possible when using a lower magnification factor lens.

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DSLR Photographers’ Must Carry Accessories

During almost every discussion with me, I have often questioned by my pals, what must to carry for the amateur photographers with DSLR. This instantly gave me an opportunity to write tips for all newbie as a piece of advice and to make their each trip memorable and not to miss any single moment with the toolkit rather I would say accessories to carry with your camera. There are certain moments that we missed just because of that missing right accessory at that particular moment. Photography is not about taking great photos but to take photos with great sense and at a perfect timing.

The basic necessity, such as memory cards and camera bags are just the tip of the iceberg when it comes to the suite of accessories DSLR owners depend on. And that goes for casual, amateur photographers, GWC (guys with cameras), and professionals. No matter you are freshly owned or a prospective DSLR owner, these are the must carry accessories that you'll want to pick up as you build your photographer's arsenal. Below mentioned are the top tips for accessories to be carry at all times.

1. Extra batteries :

The first and foremost is to have an extra pairs of batteries as this one's a no-brainer, but a newbie often ignore the importance of an extra battery. Thing is, you never want to be on vacation, at a photo shoot, or otherwise shooting photos when your battery bar morphs into a blinking red. The good news is that you can often find reliable off-brand backup batteries from Web sites like Amazon, Best Buy, or B&H Photo. When you skip the brand names (like official Canon or Nikon batteries), you can save as much as 50 percent. Just grab the battery that came with the camera, ‘Google’ the model number and read customer reviews to find out which backup battery is most suitable for your camera.

Carrying a travel charger or simple battery charger is also advisable when you are traveling and having an opportunity to recharge your batteries for having extra hours of backup.

2. Cleaning kit :

Capturing the real time shots you must blend with the nature and local environment which can possibly affect to your camera life. Keeping this in mind the second most important tool in your accessory is keeping your cleaning kit handy at all times. Whether you use a UV filter or just go commando, you should always have these things in your camera bag:

• Microfiber cloth for wiping away fingerprints and smudges
• A dust-blower for gently shooing away flecks of dirt and dust
• A cleaning pen and brush combo for precise, fingerprint-free lens cleaning

3. A Monopod or Tripod :

Choosing over monopod or tripod everybody has their own views according to its usage, though buying tripod over monopod is always a great decision as Tripod is a key to crisp images, self-portraits, long exposures, and low-light shooting. There are, however, so many types of tripods to choose from. For starters, look for a lightweight, carbon fiber tripod with a tall height and the ability to rotate vertically for the portrait shots.

From setting up a photo booth at a party to shooting photos of products or handmade items, a tripod can be a truly versatile tool. This handy guide to buying tripods does a great job of helping you narrow down which tripod is right for you. (Even you can make your own string tripod.)

4. Additional Lens :

There are some times when you get surprises as nature is full of them and do not have the proper lens to capture the event or that fraction of time going with the wind. There might be some logic in jumping with one parachute but photography isn’t that similar with paragliding and keeping additional lens is utmost important as there are several chances of macro shots during landscape photography or getting a view of landscape while doing portrait in open land. Staying alert at all times is a sign of good photographer and it rewards you back by giving you wonderful surprising shots while capturing pre-planned photo shoot.

Only thing to remember is that prepare yourself for unexpected and think out of the framework if you really want to distinguish your “Art work” rather than taking photos.

5. Camera Case :

I am not trying to be a photography guru or some but giving some tips out of my own experiences that improved my habits and learnt lessons by losing some incredible moments with some potentially awesome captures. It seems too obvious to recommend, but even newbie bent on protecting the DSLRs will postpone this necessary purchase. Even if you think your camera will mostly be hanging on your arm or around your neck, you still need a camera case.

Make sure you always think about what needs to travel with you. Extra batteries, memory cards, card readers, filters, extra lenses, and your cleaning kit will each need a cubby in your bag. Once you know what needs to be stored, you'll have a better idea of what kind of bag or backpack you'll need. Go for one that has lots of padding and external protection, so that your equipment is safe from the outside in.

6. External Hard Drive :

I shall certainly add this last but not least “must have” accessory in your kit. If you're used to the small file sizes point-and-shoot cameras produce, get ready for a big change as DSLRs produce much larger file types, especially when you're taking advantage of shooting in super high-resolution, raw, or HD video formats.

To accommodate the storage needs of these large files, purchase an external hard drive. The exact capacity will depend on how much shooting you plan to do, but I always err on the side of safety, so if you can, go for at least 1TB of storage. Here are some recommendations for the best portable hard drives. Once you've set up your hard drive, immediately establish a system for organizing your photos and videos so that you'll know exactly where to find any given photo in a pinch. I am sure you definitely will thank me later.

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How to Photography using Wide Angle Lens - Tutorial

Photography can be fun and exciting if you have a little knowledge about it and you follow certain basic rules. We have already had a glimpse for a beginners introduction to wide angle lens in our previous post. In photography, wide angle lens can be a powerful tool for exaggerating the depth and relative size in a photo. Apparently, it is considered as one of the most difficult types of lenses to understand how to make use of it. Through this post I will try to dispel some common misconceptions and will discuss the techniques to get the total benefits of the unique characteristics of a wide angle lens.

Synopsis :

A lens is generally considered to be "wide angle lens" when its focal length is less than around 35 mm (on a full frame; see camera lenses: focal length & aperture). This translates into an angle of view which is greater than about 55° across your photo's widest dimension. The definition of ultra-wide is a little fuzzier, but most agree that this realm begins with focal lengths somewhere around 20-24 mm and less. On a compact camera, wide angle is often when you've fully zoomed out, however ultra-wide is usually never available without a special lens adapter.

Regardless, the key concept is this: the shorter the focal length, the more you will tend to notice the unique effects of a wide angle lens.

What makes a wide angle lens unique? A common misconception is that wide-angle lenses are primarily used for when you cannot step far enough away from your subject, but yet still want to capture all of this subject in a single camera frame. Unfortunately, if one were to only use it this way they'd really be missing out. In fact, wide angle lenses are often used for just the opposite: when you want to get closer to a subject!

So, let's take a closer look at just what makes a wide angle lens unique:

• Its image encompasses a wide angle of view
• It generally has a close minimum focusing distance

Although the above characteristics might seem pretty basic, they result in a surprising range of possibilities. The rest of this page focuses on techniques for how to best use these traits for maximal impact in wide angle photography.

Wide Angle Perspective :

Obviously, a wide angle lens is special because it has a wide angle of view — but what does this actually do? A wide angle of view means that both the relative size and distance is exaggerated when comparing near and far objects. This causes nearby objects to appear gigantic, and far away objects to appear unusually tiny and distant. The reason for this is the angle of view.

Even though the two cylinders above are the same distance apart when photographed with each lens, their relative sizes are very different when one fills the frame with the closest cylinder. With a wider angle of view, further objects therefore comprise a much lower fraction of the total angle of view.

A misconception is that a wide angle lens affects perspective, but strictly speaking, this isn't true. Perspective is only influenced by where you are located when you take a photograph. However, in practical use, wide-angle lenses often cause you to move much closer to your subject — which does affect perspective.

This exaggeration of relative size can be used to add emphasis and detail to foreground objects, while still capturing expansive backgrounds. If you plan on using this effect to full impact, you'll want to get as close as possible to the nearest subject in the scene.

However, one needs to take extra caution when photographing people. Their nose, head or other features can become greatly out of proportion if you are too close to them when taking the photo. This proportionality is in part why narrower focal lengths are much more common for traditional portrait photography.

Regardless, don't be afraid to get much closer! This is where wide angle really shines. Just take extra care with the composition though; extremely close objects can move a lot inside the image due to camera movements of even a fraction of an inch. It can therefore become quite difficult to frame subjects the way you want.

Converging Verticals : 

Whenever a wide angle lens is pointed above or below the horizon, it will cause otherwise parallel vertical lines to appear as if they are converging. Any lens does this — even telephoto lenses — it's just that a wider expanse of converging lines is visible with a wide angle lens. Further, with a wide angle lens, even small changes in composition will alter the location of the vanishing point by a large amount — resulting in a big difference in how sharply lines seem to converge.

Although converging vertical lines are generally avoided in architectural photography for the above reasons, one can also sometimes use these to their advantage:

Wide angle lens always used to capture the towering trees in a way that makes them appear to be enveloping the viewer. A big reason for this is that they look as if they are coming from all directions and converging in the middle of the image — even though they are actually all parallel to one another.

Similarly, the architectural photo to the right was taken close to the door in order to exaggerate the apparent height of the chapel. On the other hand, this also gives the unwanted appearance that the building is about to fall over backwards.

The only ways to reduce converging verticals are to either :

• Aim your camera closer to the horizon, even if this means that you'll capture a lot of ground in addition to the subject (which you can crop out later)
• Get much further from your subject and use a lens with a longer focal length
• Use Photoshop or other software to distort the photo so that vertical lines diverge less
• Use a tilt/shift lens to control perspective.

Interiors & Enclosed Spaces :

A wide angle lens can be an absolute requirement in enclosed spaces, simply because one cannot move far enough away from their subject to get all of them in the photo (using a normal lens). A common example is photography of interior rooms or other indoor architecture. This kind of photography is also perhaps the easiest way to make the most of a wide angle lens — in part because it forces you to be close to the subject.

Polarizing Filters :

Using a polarizing filter should almost always be avoided with a wide angle lens. A key trait of a polarizer is that its influence varies depending on the angle of the subject relative to the sun. When you face your camera 90° from where the sun is coming from, you will maximize its effect; similarly, whenever you face your camera directly away from or into the sun, you will minimize the effect of a polarizer.

With an ultra-wide angle lens, one edge of your image frame might be nearly facing the sun, whereas the opposing edge might be facing 90° away from the sun. This means that you will be able to see the changing influence of your polarizer across a single photo, which is usually undesirable.

Managing Light Across a Wide Angle :

A common hurdle with wide angle lenses is strong variation in the intensity of light across an image. Using an ordinary exposure, uneven light can make some parts of the image over-exposed, while also leaving other parts underexposed — even though our eye would have adjusted to this changing brightness as we looked in different directions. One therefore needs to take extra care when determining the desired exposure.

For example, in landscape photography the foreground foliage is often much less intensely lit than the sky or a distant mountain. This often results in an over-exposed sky and/or an under-exposed foreground. Most photographers therefore use what is called a graduated neutral density (GND) filter to overcome this uneven lighting.

In the example above, the GND filter partially obstructed some of the light from the bright sky, while also gradually letting in more and more light for positions progressively lower in the photo. At the bottom of the photo, the GND filter let in the full amount of light. Move your mouse over the image above to see what it would have looked like without a GND filter. Also take a look at the tutorials on camera lens filters and high dynamic range (HDR) for additional examples.

A wide angle lens is also much more susceptible to lens flare, in part because the sun is much more likely to enter into the composition. It can also be difficult to effectively shield the sides of the lens from stray light using a lens hood, since this hood cannot also block any of the image-forming light across the wide angle of coverage.

Wide Angle Lenses & Depth of Field :

Note that nowhere in this page is it mentioned that a wide angle lens has a greater depth of field. Unfortunately, this is another common misconception. If you are magnifying your subject by the same amount (meaning that they fill the image frame by the same proportion), then a wide angle lens will give the same* depth of field as a telephoto lens.

Technical Note: for situations of extreme magnification, the depth of field may differ by a small amount. However, this is an extreme case and is not relevant for the uses discussed in this page. See the tutorial on depth of field for a more detailed discussion of this topic.

The reason that wide angle lenses get the reputation of improving depth of field is not because of any inherent property with the lens itself. It's because of how they're most often used. People rarely get close enough to their subject to have them fill the same amount of the frame with a wide angle lens as they do with lenses that have narrower angles of view.

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