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Learn Photography- By AK Picarts ~Focusing Basics~

Focusing Basics

Understanding Depth of Field in Photography

In this section we’re going to discuss several crucial elements for exercising greater creative control over your final photographic image. Other than lighting, composition and focus (which includes depth of field) are the main elements that you can exercise complete command over. Focus enables you to isolate a subject and specifically draw the viewer’s eye to exactly where you want it. The first thing to understand about focus is depth of field.

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Depth of Field

Depth of Field (DOF) is the front-to-back zone of a photograph in which the image is razor sharp. As soon as an object (person, thing) falls out of this range, it begins to lose focus at an accelerating degree the farther out of the zone it falls; e.g. closer to the lens or deeper into the background. With any DOF zone, there is a Point of Optimum focus in which the object is most sharp. There are two ways to describe the qualities of depth of field - shallow DOF or deep DOF. Shallow is when the included focus range is very narrow, a few inches to several feet. Deep is when the included range is a couple of yards to infinity. In both cases DOF is measured in front of the focus point and behind the focus point. DOF is determined by three factors – aperture size, distance from the lens, and the focal length of the lens. Let’s look at how each one works.

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Aperture

The aperture is the opening at the rear of the lens that determines how much light travels through the lens and falls on the image sensor. The size of the aperture’s opening is measured in f-stops - one of two sets of numbers on the lens barrel (the other being the focusing distance). The f-stops work as inverse values, such that a small f/number (say f/2.8) corresponds to a larger or wider aperture size, which results in a shallow depth of field; conversely a large f/number (say f/16) results in a smaller or narrower aperture size and therefore a deeper depth of field.

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Small vs Large Aperture

Manipulating the aperture is the easiest and most often utilized means to adjust Depth of Field. To achieve a deep, rich and expansive DOF, you’ll want to set the f-stop to around f/11 or higher. You may have seen this principle demonstrated when you look at photos taken outside during the brightest time of the day. In such a case, the camera is typically set at f/16 or higher (that Sunny 16 Rule) and the Depth of Field is quite deep - perhaps several yards in front of and nearly to infinity beyond the exact focus point. Let’s take a look at these two photos as examples. The photo on the left has an expansive DOF, most likely shot around noon (notice the short, but strong shadows), with an f/22 aperture. The photo on the right has an extremely shallow DOF; probably an f/2.8 aperture setting. However, to achieve an identical proper exposure, the shutter speed is probably closer to 1/1000th to compensate for the increased amount of light entering the lens at f/2.8.

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Aperture Range

The aperture range identifies the widest to smallest range of lens openings, i.e. f/1.4 (on a super-fast lens) to f/32, with incremental “stops” in between (f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, and f/22). Each f-number is represents one “stop” of light, a stop is a mathematical equation (which is the focal length of the lens divided by the diameter of the aperture opening) that determines how much light that enters the lens regardless of the length of the lens. Such that an f/4 on a 50mm has smaller opening than an f/4 on a 200mm, but an equivalent amount of light travels through both lenses to reach the image sensor thus providing the same exposure. Each movement up the range (say f/2 to f.2.8) reduces the amount of light by one-half and each movement down the range (say f/11 to f/8) doubles the amount of light passing through the lens. It’s important to understand this concept and how it affects exposure because it works in tandem with the shutter speed (we’ll discuss this in another section) to establish a given exposure value. Basically, when you change the aperture size one stop, you have to shift the shutter speed one stop in the opposite direction to maintain a consistent exposure… and this change in aperture alters the depth of field (DOF) accordingly.

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Distance from the Lens

The last element affecting depth of field is the distance of the subject from the lens - you can adjust the DOF by changing that distance. For example, the closer an object is to the lens (and the focus is set on that object) the shallower the DOF. Conversely, the reverse is true - the farther away an object is and focused on, the deeper the DOF. Changing the distance to subject is the least practical way to manipulate the depth of field, and by changing the distance from a subject to the lens, you immediately change your image’s composition. To maintain the compositional integrity of the shot, but still have the change in DOF from a distance, you can change the focal length (either by changing lenses or zooming in). Why does changing the focal length negate the effects on DOF? This is because the visual properties of a given lens either provide either greater DOF (shorter lenses) or shallower DOF (longer lenses). The physical properties of a lens at a given focal length also affect the depth of field. A shorter focal length lens (say 27mm) focused at 5 meters, set at f/4 has a deeper DOF (perhaps from 3 meters in front and 20 meters behind) than a longer focal length (say 300mm), also set at f/4 focused at 5 meters. The 300mm lens has a remarkably shallow depth of field. Incidentally, to help you with this, every lens has a manual with a DOF chart for each f/stop and the major focusing distances. DOF is just a matter of physics, and it’s important to grasp this concept.

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Conclusion

Manipulation of depth of field is a good way to modify the characteristics of your photo, and manipulating the aperture is the ideal way to do this because it has little or no effect on composition. You simply need to change the shutter speed (or change the light sensitivity – ISO) to compensate for the changes in the exposure from the adjustments to the f-number. Changes in distance and focal length also affect DOF, but these changes have trade-offs in terms of composition. Therefore, changes to aperture are the best way to manipulate DOF without affecting a photo’s composition.

Learn Photography- By AK Picarts ~ISO Sensitivity~

ISO Sensitivity

Learn How ISO Sensitivity Works

ISO or light sensitivity rating is an algorithmic value that indicates the film’s or the image sensor’s specific sensitivity to light. The ISO values on a roll of film or ISO setting on a digital camera are these indicators.

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ISO Sensitivity

ISO is actually an acronym, which stands for International Standards Organization, and the ISO rating along with the shutter speed and aperture setting are the three elements that determine the final exposure of the photographic image. The ISO rating, which ranges in value from 25 to 6400 (or beyond), indicates the specific light sensitivity. The lower the number, the less sensitive to light the film stock or image sensor is. Conversely, a higher number indicates a higher sensitivity to light, thereby allowing that film or image sensor to work better in low light conditions.

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ISO Sensitivity and Image Noise

With film stocks, the lower ISO rating also meant that the photosensitive grains of salt on the film acetate were very fine, thus producing a smoother, cleaner image. A higher ISO had larger, jagged grains of salt, thus producing “rougher” or grainier images. In digital photography, the same logic applies… the lower the ISO rating, the less sensitive the image sensor is and therefore the smoother the image, because there is less digital noise in the image. The higher the ISO rating (more sensitive) the stronger the image sensor has to work to establish an effective image, which thereby produces more digital noise (those multi-colored speckles in the shadows and in the midtones). So what is digital noise? It is any light signal that does not originate from the subject, and therefore creates random color in an image. The digital camera engineers have designed the image sensor to perform best at the lowest ISO (just like with film). On most digital cameras this is ISO 100, although some high end DSLRs have a mode that brings the ISO down to 50 or even 25.

One more thing about the “grain”; in the old fashioned non-digital image many film photographers found ways to creatively and artistically utilize the grain to affect the final mood and tone of an image. Unfortunately, due to the nature of digital noise (as it manifests as random clumps of colored speckles), it is highly undesirable. However, some photographers have found limited creative ways to use digital noise. Maybe you can join that rare club.

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ISO Speed vs. Motion Blur

Lower ISO ratings produce color-accurate, smooth and aesthetically appealing images… and this requires ideal lighting conditions. However, there are some subjects that you want to photograph in low light conditions. Or, you may want to stop fast-moving objects (a humming bird, a race horse or a carousel). In both situations, you need higher ISOs to capture those images with an acceptable exposure. Unlike film, with a digital camera you can increase the ISO with the touch of a button, and this flexibility makes it much easier to get the image you want. So with the higher ISOs, you can use faster shutter speeds to eliminate motion blur and/or camera shake. In the event that you want to use motion blur creatively, then decreasing the ISO is simple, and you can then decrease the shutter speed (less than 1/30s) to achieve the desired motion blur and still have smooth, noise-less images.

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ISO Speed and Image Sensor Size

The size of the digital camera’s image sensor dictates what ISO setting provides the least amount of digital noise. One must understand that image sensor size is not the same thing as pixel count. Image sensor size is the actual physical dimensions of the sensor, for most of the history of digital photography the image sensor has been smaller than a 35mm film frame. On point and shoot cameras, the sensor was quite small, and on most DSLR cameras, the image sensor has been the size of APC film (23x15mm). Smaller image sensors produce much more digital noise at higher ISOs (like 800) mainly because the high pixel count means that more pixels are being packed into a smaller area, thus producing more grain at all but the lowest ISO.

Currently, many DSLR manufacturers produce image sensors the same size as a 35mm film frame (called Full Frame). The larger Full Frame sensor allows for more and larger pixels to be packed onto the image sensor, thus allowing for smoother, grain-free images at ISO setting of even 1600 (in some cases). On Full Frame sensors, the larger pixels are individually more sensitive to light, so the electronic energy required to mimic ISO 800 doesn’t create the same amount of digital noise as with a smaller image sensor. The Full Frame cameras enable you to capture dynamic and effective images in a variety of challenging or low light conditions without extraneous digital noise.

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Image Quality and ISO Sensitivity

It is important to remember that the lower the ISO rating the better the image quality is going to be. While most digital cameras have a default “Auto ISO” setting, this reduces your control because it can automatically set a higher ISO, which will result in a grainier (noisier) image when other settings could have created an acceptable exposure with less noise. Increasing ISO affects image quality in two major ways: 1) The distinction between fine details is reduced. 2) When you enlarge the image and make digital prints, or when you save the image as a jpeg (which has a high level of compression), the inherent high level of digital noise will result in a “muddier” image after conversion.

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Recommended Settings

As we’ve stated, the lower the ISO the smoother, cleaner, and “better” images you will have. Lower ISO images will be more color-accurate and more aesthetically captivating. ISO between 100 and 200 will give you the best results, and depending on the image sensor and the camera’s engineering you can get away with ISO 400 and still have clear, clean and sharp images for the vast majority of enlargements (up to 20x24).

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Conclusion

The image sensor’s light sensitivity (ISO) is important when acquiring and crafting any digital photographic image, and the reciprocal scale basically trades off a smooth final image with higher ISO rating. The image sensor’s light sensitivity is important in how you craft your photographs. For example, you might need to bring in additional light sources to keep the ISO as low as possible for smoother photos. So when you’re faced with adverse lighting conditions (i.e. low light or high contrast lighting) or require higher shutter speed you must sacrifice the smoothness available with a low ISO to get the shot with a higher ISO. In other words, increase the ISO and deal with the consequences later, because if the alternative (a lower ISO setting) means that you miss the shot, then it is better to make the trade off.

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Learn Photography- By AK Picarts ~Exposure~

Exposure

Understanding Exposure - ISO, Aperture and Shutter Speed Explained

When you think of the craft or art of photography, you must immediately think of exposure. Exposure is a critical element that determines what is actually recorded on film or the image sensor. There are three adjustable elements that control the exposure - ISO, Aperture and Shutter Speed.

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What controls exposure?

ISO ratings determine the image sensor’s sensitivity to light, each value of the rating represents a “stop” of light, and each incremental ISO number (up or down) represents a doubling or halving of the sensor’s sensitivity to light.

The Aperture controls the lens’ diaphragm, which controls the amount of light traveling through the lens to the film plane. The aperture setting is indicated by the f-number, whereas each f-number represents a “stop” of light.

The Shutter Speed indicates the speed in which the curtain opens then closes, and each shutter speed value also represents a “stop” of light. The shutter speed is measured in fractions of a second.

When these three elements are combined, they represent a given exposure value (EV) for a given setting. Any change in any one of the three elements will have a measurable and specific impact on how the remaining two elements react to expose the film frame or image sensor and how the image ultimately looks. For example, if you increase the f-stop, you decrease the size of the lens’ diaphragm thus reducing the amount of light hitting the image sensor, but also increasing theDOF (depth of field) in the final image. Reducing the shutter speed affects howmotion is captured, in that this can cause the background or subject to become blurry. However, reducing shutter speed (keeping the shutter open longer) also increases the amount of light hitting the image sensor, so everything is brighter. Increasing the ISO, allows for shooting in lower light situations, but you increase the amount of digital noise inherent in the photo. It is impossible to make an independent change in one of the elements and not obtain an opposite effect in how the other elements affect the image, and ultimately change the EV.

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ISO Speed

ISO is actually an acronym, which stands for International Standards Organization. The ISO rating, which ranges in value from 25 to 3200 (or beyond), indicates the specific light sensitivity. The lower the ISO rating, the less sensitive the image sensor is and therefore the smoother the image, because there is less digital noise in the image. The higher the ISO rating (more sensitive) the stronger the image sensor has to work to establish an effective image, which thereby produces more digital noise (those multi-colored speckles in the shadows and in the midtones). So what is digital noise? It is any light signal that does not originate from the subject, and therefore creates random color in an image. The digital camera engineers have designed the image sensor to perform best at the lowest ISO (just like with film). On most digital cameras this is ISO 100, although some high end DSLRs have a mode that brings the ISO down to 50 or even 25.

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Aperture

A lens’s aperture is the opening in the diaphragm that determines the amount of focused light passing through the lens. At a small f-stop, say f/2, a tremendous amount of light passes through, even at a fraction of a second; but at f/22, when the diaphragm is perhaps at its smallest, only a tiny amount of light is let in (even at longer shutter speeds). An interesting thing about the aperture and the f-numbers is that it doesn’t matter the focal length of the lens as long as the f-number is held constant. This is because the arithmetical equation that determines the f-number indicates that the same amount of light passes through the lens on a 35mm lens as on a 100mm lens, with a shutter speed of 1/125s. The size of the diaphragm is unquestionably different, but the amount of light passing through is the same.

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Shutter Speed

Shutter speed is measured in fractions of a second, and indicates how fast the curtains at the film plane open and close. The shutter speed controls how long light enters the lens and hits the image sensor or film plane. The shutter speed enables you to capture the world in split seconds, but it can also absorb the world at speeds upwards of three and four seconds (or remain continually open up until the photographer wants to close the curtain). Snapping the shutter in a fraction of a second, also gives you control on how motion is recorded. If the shutter speed is faster than the object or background, then the image will be tack sharp. If the shutter speed is slower, then you’ll get blurred objects. Think about the rain in a rainstorm, how fast is that water falling? Well, at 1/30th the raindrops are streaks of undistinguishable white. But at 1/250th, the raindrops hover in mid air and you can see the full swell of each water drop.

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What is "Auto Bracketing"?

Auto Bracketing is an exposure technique whereby you can ensure that you have the optimal exposure by taking at least three (3) exposures of the exact same composition with one at the metered EV, one at 1/3 of a stop below the metered EV and one at 1/3 of a stop above the metered EV. So “Auto Bracketing” is a function in which you set the EV value then release the shutter and the camera automatically makes the necessary up and down adjustments to the EV to give you the bracketed exposures. Then you can review the three (or more) exposures, see the subtle but critical differences in the images, and decide which one is the best image for your purposes. In the three images on the right, you might prefer the overexposed (by 2 stops) image because the setting sun is most brilliant. Bracketing was a technique that was popularized from shooting slide film, due to the limited ability to correct the image in the darkroom. Many photographers still use the technique today, so they have the exposure that they want. Having the three bracketed images lowers the amount of post-processing time that they might have to spend.

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Overexposure & Underexposure

How do you define overexposure and underexposure, since we said that “correct” exposure is subjective? Simply put, overexposure is when the information in the highlights is effectively unreadable. When there is this type of excessive loss of image information there is no way to “retrieve” that missing information in the digital dark room. Underexposure is pretty much the same concept; except in this case there is no image information contained within the shadows. This non-existant information cannot be retrieved through post processing either. In digital photography, once that image information is gone, there’s no way to retrieve it. This is not always the case in the photochemical world of film photography. With film (as opposed to digital) processing, it is possible to “find” image information in an excessively underexposed frame, and perhaps “find” image information during the printing process for seriously overexposed images as well.

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AE LOCK (AEL)

Auto Exposure Lock is a camera setting in which the EV is locked in (when you’re shooting one of the semi-automatic or fully automatic modes, i.e. Shutter-priority), so that now matter what changes there are to the lighting in the scene, the camera locks in the ISO, Shutter and/or Aperture settings, so you can continually achieve the same EV without having to re-meter the scene.

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Conclusion

One highly practical advantage to digital photography is that it costs next to nothing to experiment with the camera’s controls, so go out there and shoot away. You want to become increasingly proficient with all three elements of the exposure triangle, so that you can make adjustments on the fly and know exactly what the resulting effect is going to be.

Learn Photography- By AK Picarts ~Baby Photography Tips~

Baby Photography Tips

Take Your Portrait Photography to the Next Level!

Few things in life can be as rewarding as photographing babies- after coaxing an expression of cherubic joy - caught with a click. Here are some easy steps you can follow to take the perfect portrait of the apple of your eye.

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Click Away!

Babies are unpredictable so therefore tears and tantrums are to be expected. Don’t be afraid to keep the camera shooting rather than waiting for that perfect pose or moment because somewhere in 30 consecutive shots will be one winner. Presuming you have a good amount of natural daylight, choose an ISO of 100-400 and use a wide aperture (f/2.8-f/8) for a shallow DOF (depth of field). Use continuous shooting mode on your camera to capture 2, 3, 4, or 5 photos in a couple of seconds.

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Check the Lighting

For the best baby shots, photograph during the daytime when there is plenty of natural daylight. Natural light gives a soft focus look to the baby’s skin. Use window light if possible and avoid the harsh sun because it tends to casts shadows and is also unhealthy for the baby’s skin. A standard lens of 50mm is ideal for this kind of image. Turn the mode dial to AV (Aperture Priority) mode, select a high ISO and a wide aperture. Let the camera choose the correct shutter speed. Use an external flash (with a diffuser) to fill in any dark spots.

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'Smile for me Baby'

When photographing babies, you may need to “ham it up” to elicit a reaction. This can include making funny faces, playing hide and seek from behind a piece of cloth, or making goofy clucking noises. There are so many ways you can coax a smile onto an infant’s lips. Get “your better half” to coax that perfect expression, as you set up the shot. You should work fast to capture the moment so choose a fast shutter speed of 1/500s or more, use a wide aperture (f/1.8-f/4) for a blurred background and shoot!

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Simple Backgrounds

Simple baby shots are usually the best; there is no need for cluttered or overly bright backgrounds. A great way to get a photo that looks professional is to get some white, grey or beige cloth and lay it over two chairs. Place the cloth near a large window with the baby on it with some toys. Turn the mode dial to AV (Aperture Priority) mode and select your desired aperture. Feel free to push the ISO up if the window light is not very bright. Spot meter on the baby's face and focus on the baby's eyes.

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Make it Memorable

To take memorable pictures try to capture the baby engaged in an activity, or with family and friends. Siblings, especially if they are close in age can add extra interest to the photograph – get them playing together, eating or interacting as friends. Keep back and don’t try to force friendliness – let the children do what they do. Take the photos from the background, so as not to disrupt them. Seat the kids in an uncluttered area that has lots of natural light, like a large window. Use the auto settings to make sure you get a sharp image, and let the camera choose flash if it is necessary.

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Be Adventurous

Black and white images are classic and timeless, and are perfect for photographing babies! Turn the mode dial to AV (Aperture Priority) mode and select a large aperture for a soft and blurred background. Use the spot metering mode and meter on the baby's face. When shooting in monochrome consider contrast; black and white backgrounds will be the most striking, and contrast in the lighting will also give a dramatic effect.

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Recommended Settings

Generally when working with babies, we want to be quick and without hesitation. Therefore choose fast shutter speeds and/or high ISOs. There’s nothing worse than capturing a great moment that is slightly blurry because the shutter was too slow. With good daylight you want to use 1/500s shutter speed. F/5.6 and wider is also a good rule of thumb in terms of aperture, giving sharp shots without sacrificing shutter speed.

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Recommended Equipment

As well as a good camera, a standard lens of around 50mm is a good tool for baby portraits. Try to choose one with f/1.8 and lower so you get faster shutter speeds and sharper shots (i.e. f/1.4 and f/1.2). A beanbag rather than a tripod is great for stabilizing your camera and getting down on the ground to a baby's level, and a silver or white reflector is ideal for bouncing light so that it is soft and flattering.

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Conclusion

Babies offer a great opportunity for creating beautiful and treasured photographs, though they are by no means an easy subject! Always think on your feet and shoot more images than you think you’ll need. Be open, friendly and playful – if you are awkward the baby will be too. Also, don’t forget to have a helping hand. Babies crawl, they cry, they need changes, etc. A chaperone or helper will make all the difference so that you can focus on capturing the best moments.