Photography articles

Virtually all but the cheapest digital cameras have some form of auto focusing feature built into them. In practice, using the system is fairly easy and intuitive – we are going to let the camera decide where the object is that we are photographing, so that it can then adjust the focus accordingly to capture the sharpest possible image. But how does this actually work?

The explanation of how auto focusing works is actually tied to a concept that is getting more exposure in newer digital cameras: the histogram of pixel intensities for a given digital image. You can view this histogram on your LCD screen after you have captured an image. What it shows is a graphical display of the number of pixels that have recorded a given brightness value in the image.

Basically the graphical display is a series of thin vertical bars stacked side by side. On the leftmost side of the display is the bar showing the number of pixels that recorded a dark value (no light was captured by these pixels), while on the very right of the display is the bar showing the number of pixels that recorded the brightest possible value. As you move from left to right, the intensity associated with the pixels increases, and the height of the bar indicates the number of pixels which recorded that intensity.

So what use is viewing a histogram?

Well, if an image is excessively underexposed, virtually all the pixels will be dark and the vertical bars in the histogram will all be pushed to the left. Alternatively, a histogram with all the bars pushed to the right suggests that most of the pixels recorded a high light intensity and therefore the image is probably over exposed. Most properly-exposed images show a distribution of pixel light intensities that are crowded toward the middle of the histogram.

There are exceptions to this rule. For example, if you shoot a picture of a model silhouetted against a bright window, most of your pixels will either be on the underexposed model, or on the overexposed background provided by the window pane. The histogram will therefore show a sizable number of bars at both the left and right of the histogram, and nothing much in its center.

For regular photographic scenes, however, the histogram offers a great way to size up the overall exposure of the image in a non subjective way. Moreover, the histogram provides a quantified measure of image exposure that the brains of the digital camera can use to understand what it is that it is looking at.

This insight into the nature of light intensity histograms is the key to understanding how auto focusing works.

Some of the newest high-end digital SLR models feature over fifty separate auto focusing areas in the metered image. This means that most of the image can be metered before a final focusing length is selected for the shot. For purposes of this article we need only consider how one of these auto focusing, or AF, elements does its job.

The metered area of a single AF element might represent only one percent of the overall image, but it nonetheless represents a tiny digital image in itself and it has its own little histogram associated with it. So how might looking at a histogram tell us whether or not the image it represents is focused or not?

To make the explanation as simple as possible, let’s suppose the AF element contains a dark insect, a fly, hanging in the air far from the background elements behind it which have merged into a light blurred backdrop. When the fly is in focus, the contrast between the fly and its background is very distinct. There are dark pixels (the fly) and light pixels (the background). Sound familiar? The histogram would have peaks in the lower and upper parts of its intensity distribution, similar to the silhouetted model standing in front of the window pane.

Now consider what happens as the AF element containing the fly is defocused. The image grows increasingly less distinct as the fly blurs into a grey smear that now diffuses throughout the entire element. The corresponding histogram shifts from a bimodal distribution to a much more uniform one as the peaks spread out toward the center of the histogram.

This is how the camera can quantify the degree of sharpness, or contrast, in any given image element. Auto focusing works by optimizing the histogram for non uniformity in the distribution, which it assumes defines the best focusing.

In practice the method works fairly well. But there are situations in which the surveyed scene does not lend itself well to accurate auto focusing.

For example, poorly-lit scenes offer low contrast, and therefore make the point of sharp focus hard to define. Other times, if multiple AF elements are being used to select the best focus, the background might provide the most contrast in the image and the object you are hoping will be targeted for focusing is actually ignored because its contribution to the auto focusing argument is outweighed by the contributions due to the background.

If you were trying to focus on a hummingbird that hung a few feet in front of a tree you might be surprised when the bird blurred into a non distinct spot and the leaves of the tree rendered perfectly sharp – the precise opposite of what you had hoped would happen. In cases like this you need to switch off the multiply metered AF elements and use a single AF element to monitor just the object you are intending to focus upon. You might use just the center AF element in a case like this.

Auto focusing is an extremely useful element of modern photography, virtually indispensable to practitioners of sports and wildlife photography. But it also proves handy in a wide range of everyday photographic situations, since the world around us is rarely ever at rest. So learn to appreciate the auto focusing mechanism in your camera, understand its strengths and limitations, and in the long run this will help you to increase the quality of your photographic portfolio.

To help you select a suitable digital camera to get started with, I have put together an article for you about how to find the right Beginner Digital Camera.

Whether you need a simple point-and-shoot model, or a more complex digital SLR model, you will find the answers, and greatly discounted digital camera offers, at http://www.bestdigitalcameradiscounts.com/

The baby finally is here, so everyone wants photos! However, every time you want to take photos, the beautiful baby turns out like a wrinkled little old man rather than a gorgeous being that he is. So I decided to provide you with some tips on how to pictures of your newborn ang get the best results. First: You need to turn the Flash off! Using window light as a source of natural light is the best type of light you can use to capture pictures of your baby baby. So, just search for a window which has a lot of good light try not to use direct sun light, but go for indirect sunlight. Then, remove clutter and other stuff from the shots background by putting your baby inside a carrier and cover the carrier with a solid blanket that covers it, or even simpler, put it on a bed that has white sheets on. Remove babies clothing except the diapers. The less clothing he has the better it is for newborn photography as it really emphasizes the baby because they dont tend to fit clothing very well in this age, plus clothing acts more as a distraction. If diapers have any cartoons imprinted on, try covering them by folding the diapers over, or by putting some fabric over the area that has cartoons even more drastic, remove the diaper! You have to work fast if you decide to take this route. After you get the camera ready, make sure babys body and face are turned towards the natural light coming from outside through the window, and then start taking photos using different angles. Try filling the entire frame using the baby plus the solid sheet or blanket again try to avoid items or clutter which could get into your way. Dont try getting the baby to smile – only take a few images using different angles, some of baby looking towards the camera plus some of baby\’s profile, then some of the heads top. Keep changing angles while singing and talking to the baby and try engaging him. If he starts fussing, try and soothe him and when he is calm, take another shot. If the baby falls asleep, no problem take pictures while he is sleeping! Take more photos than you actually need youll never know which pictures youll like. Get come half body, full body, close ups of hands, face, feet plus all the other memorable, cute, body parts for example the funny hair lines, the wrinkly shoulders, his funny mouth, lips, and much more. And in the end, its time to develop the pictures either on your PC or in a lab, for developing the pictures, take your time and go through them again, and look at them with an artistic eye, and remember that you have captured the most important moments of your children forever on the camera!

Lighting Techniques Strobes: A lot of people don’t know what strobes are. It’s basically just a giant external flash. It’s the same thing as a flash that you would have on a camera. Usually, they’re round and it has a little flashbulb that’s on it that’s in the round circle. And you can control these with an external flash sync cable and it syncs right up to your camera. They even have a wireless device that will actually trigger the external flash and trip when you hit your button to push down for when you want to take the picture. Strobes are used in the professional world that every photography studio uses. There’s all different kinds. There’s some basic ones; there’s some middle of the road; and there’s some high-end ones. In this case, you’re not going to need something that’s going to be that high-end. Defused light: You have different kinds of devices to create defused light. You have an umbrella. A lot of people have seen these. And there’s different ways to defuse the light. You can take the strobe and you can bounce it off of the umbrella and then shoot it back to your subject. That creates a nice soft light or you can turn the actual strobe around and shoot through the umbrella to your subject. That’s another way to create a nice soft light. My Favorite is the soft box, it’s basically a huge box just like it says and it has a white screen over it and you shoot right through it. And it usually gives a really nice light that wraps around your subject. Budget Lighting: You can create your own. I’ve seen this done–where you take some 2x4s and you nail them together and you take a white sheet and you stretch it over the 2x4s and then you shoot your strobe through it. And that creates your soft box. It’s basically the same thing. So those are some options for diffusing your light. Using window light can work really well, but you need a window in the room and if you’re traveling with this portable studio that I’m going to show you how to do, you might not have a window light in that room. But if you do, you just want to find a window nearest your subject and then bounce the light with a poster board on the other side or a sheet. Something white. So you can be creative with that. But something white to bounce that light from the other side. Because if you only have a window on one side of the room, then you’re going to want to fill in on the other side with a reflector or you might get lucky and have two windows on either side of the room. That would be your best scenario. And then natural light can be really, really nice. And that’s what window light is. It’s just a nice even light. If you’ve ever shot outdoors on an overcast day, you can see that the outside light is nice and even. So that’s window lighting. Outside Lighting: Basically, you’re just going to set everything up outside just like you would in a studio.  Basically just set up your mini-studio outside. Use a poster board or a reflector to direct the light. Again, it’s almost what you see is what you get. So I would look and see where your best positioning is when you put a subject on the area where you’re going to be shooting and see if you see any shadows. And if you do, well you’ve have to move the subject because that’s the advantage with outside lighting. If you see a shadow, you get a shadow. It’s pretty easy to remove them with a few basic techniques. Just take a poster board or something white and reflect the light or bounce the light back in. If you have an external flash, you can use use a fill flash and that will fill in for shadows as well. Using your overcast skies to create a nice even soft light. Think of this as a giant soft box, so use it whenever possible. If you think it’s overcast and it looks gloomy, it’s usually your best light. Create a screen to defuse the sunlight. Now if you have a real bright sunny day and there’s no area where there’s shade, you can create a defused light source by taking the same idea I talked about with the defused light of creating your own. You can take some 2x4s and put them together or pieces of wood and stretch a piece of sheet over them. And you can either build a stand or you can have someone hold it over your subject and that creates a nice even light as well.