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DSLR Guide News - Get the Most From Your Kit Lens
August 01, 2010
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What many advanced photographers have come to realize is that good photography isn't really about the gear - it's about what you do with the gear you have.
When I first started taking pictures, I was constantly reading up on the latest lenses, flash units and other accessories that I could add on to my camera to make my photos spectacular. Now, I pretty much just use what I've got.
If there's a shot that seems beyond the limits of the gear that I own, I get creative about how I use my existing tools rather than running to the camera store, credit card in hand.
That's why the topic of this beginner photo tip is how to get the most out of your 18-55mm lens (the most common zoom lens sold as a kit with digital SLR cameras).
The first step is to become intimately aware of the LIMITS of your lens. Knowing its boundaries will help you judge whether a shot is possible before you even try to take it.
The main limit on any lens is something called the maximum aperture: this number (or numbers) represents the maximum width of the lens and also tells you how much light a lens can let in.
Instead of a lens, think of curtains on a window. If the curtains are wide open, then lots of light comes through the window. If you shut them halfway, then less light enters the room. If they are closed to just a slit, then the light in the room will be quite dim.
Lens apertures are measured in f-stops, and large f numbers (f/16, f/22) mean the lens opening is narrow while small f numbers (f/3.5, f/5.6) mean the lens is open wide.
Going back to your standard kit lens, you'll often hear to it referred to as an 18-55mm f/3.5-5.6. There are TWO wide f numbers listed here and there's a reason for that: the maximum aperture of an 18-55mm lens gets NARROWER as you zoom the lens.
At 18mm, the maximum aperture is a wide f/3.5, but zoomed to 55mm, the max aperture narrows to f/5.6.
Now that we've covered some of the techno-jabber, let's talk about WHAT these maximum apertures mean for you when you're trying to take pictures.
If action photography is your passion, then you're going to constantly run up against maximum aperture. Here's why: you need to leverage the max aperture of your lens for action shots — a wider aperture provides you with a faster shutter speed.
If you don't want your action subjects to look like giant blurs in your photos, you MUST use fast shutter speeds between 1/250th and 1/1000th of a second. In order to get shutter speeds this fast, the lens has to be letting in a lot of light.
This means that if you want to take a lot of action shots with an 18-55mm kit lens, then the majority of those photos will have to be captured with the lens set to 18mm (wide angle) so that you can take advantage of the wider f/3.5 max aperture.
Try it for yourself:
You should quickly notice two things: 1) the aperture has narrowed to f/5.6 (even though you didn't change it) and 2) the shutter speed is now slower than it was before.
One way to compensate for the slower shutter speed is to use a higher ISO setting. For example, if you did the above exercise at ISO 100, you'll be able to boost your shutter speeds (at all settings) if you use ISO 800 instead. But a higher ISO does result in more image noise, so you don't want to be using ISO 1600 all the time.
I've talked a lot about action photography (because it's by far the trickiest in terms of lens settings) but what about other styles? What if you're into landscapes and portraits?
Landscape photographers - happily - have very few challenges when it comes to lens usage. Since your subject isn't moving, you can use just about any old shutter speed you want (provided the camera itself remains stable).
You also won't ever run into the max aperture of the lens, because you'll want to use narrower apertures between f/8 and f/22 to keep everything from foreground to background in focus (also called infinite depth of field).
For portrait photography, you can use wide apertures, but in this case it won't be to maximize shutter speed. Instead, you'll use the wide aperture to LIMIT depth of field to create a nice blurred background behind your subject.
To maximize the blur effect, you should also set your lens to its telephoto 55mm setting (since longer focal lengths also limit depth of field). The long focal length paired with a wide lens aperture should reduce the sharpness of the background so your portrait subject really stands out.
While AUTO - or TTL - flash is just fine for point-and-shoot type situations, if you've got a bit more time and want better control over your exposure then manual mode flash is the way to go.
Now, you don't need any fancy equipment to use manual mode flash - the technique that I'm about to describe even works with built-in flash.
So, ready to make the switch to manual mode flash?
How easy was that?
All right, I suppose that some more in-depth information is required here for this to make sense.
In manual mode, you have control over both the aperture and shutter speed - the camera isn't picking either one for you (unlike auto mode, where it picks BOTH).
Now, here's the odd part. If you weren't using flash, having manual control over aperture and shutter speed would let you deliberately over or under expose your photos. However, when you're using a TTL flash, changing these settings does NOT really affect your exposure. Instead, it impacts the amount of light your flash puts out.
Let's take a closer look.
Keeping shutter speed at a constant 1/60th of a second, let's play around with the aperture setting.
While the exposure on both photos should look pretty much the same, you should notice that the flash doesn't put out as much light when the aperture is wide.
In the end, your TTL flash is striving for a perfect exposure every time. When you use a wide aperture in dim light, your photo might be only mildly under exposed - the flash just has to provide a small amount of additional illumination to get the exposure right. However, when you select a narrow aperture your image without flash is massively under exposed - in this case, the flash is the ONLY source of light and it therefore has to use more power to ensure a proper exposure.
So changing aperture affects the power level of the flash: wider apertures use less flash power while narrow apertures use a lot. But what about shutter speed?
If you keep your aperture constant and adjust shutter speed instead, you may not notice that it has any real impact at first. This is because the effect of shutter speed on flash photos is a subtle one.
Simply put: changes to shutter speed when using flash ONLY impact the brightness of the background, NOT the subjects closest to the camera.
This is because the light from your flash is responsible for lighting up anything that's close to the camera. And remember, your flash is striving to light everything evenly. Since your flash has limited power, some things in the far background won't be lit by flash.
It is these elements that are subject to changes in shutter speed. If you increase the shutter speed they'll get darker and if you slow down the shutter speed they'll get brighter.
You can leverage this to either show or hide the background behind your primary subject. For example, let's say that you're taking a portrait and the background is very cluttered. Since you don't want that cluttered background to compete with your subject, you can make it go dark: activate your flash and choose a fast shutter speed to reduce the brightness of the background.
Conversely, you may find that you want the background to be brighter so more detail is apparent: just slow down the shutter speed accordingly.
One note of caution if you do try to use slow shutter speeds: motion blur WILL become a problem if your shutter speed gets too slow. You'll need to find a way to stabilize your camera if you want your slow shutter flash photos to turn out nice and sharp.
We've now covered three aspects of a camera's LENS in this Back to Basics section: the focal length, how it focuses, and what it's aperture is.
Now we'll take a break from talking about what the lens can do and will instead talk about the most fundamental setting inside your CAMERA: something called shutter speed.
At its most basic, shutter speed breaks down like this:
Simple right? If only that were so — this is just the tip of the iceberg when it comes to talking about shutter speed.
The reason it's a little more complex than the two bullets above is due to the NUMBER of ways in which a subject and/or camera can be in motion.
Here are just a few examples:
As you can see, either the camera, subject or BOTH can be in motion at the same time. Trying to capture perfectly clear shots when there is a lot of motion, or intentionally adding some motion blur to your photos is part of the fun of working with shutter speed.
Motion blur becomes apparent at shutter speeds right around 1/60th of a second. This is a very general rule of thumb, because a lot depends on the subject.
If you're dealing with a subject that moves VERY fast - cars, planes, etc. - then you'll need much faster shutter speeds (1/500th of a second) if you want to completely eliminate blur. For less speedy subjects anything between 1/125 and 1/320 should work well.
As for the camera, its motion won't really affect your photos until you get to shutter speeds that are slower than 1/15th of a second. At this point, you're really running the risk that your entire photo will look blurry due to the shaking of the camera.
If you're taking pictures of static subjects, you can eliminate all blur completely by using a tripod. With a tripod, you can select ANY shutter speed you want and motion blur won't be apparent in your photo unless a moving subject passed through the scene while the shutter is open.
Shutter Speed NotationShutter speeds are measured in seconds and fractions of seconds.
Unlike maximum aperture - where there is a lot of variation between lenses about how wide they can open - virtually all digital SLR cameras can use the same shutter speeds (although some have higher maximum speeds than others).
The fastest shutter speed on most cameras is 1/4000th of a second - fast enough to freeze the motion of just about ANY moving subject. At the opposite end, shutters can be left open for as long as 30 seconds for dynamic night-time photographs.
If you look at your camera for the shutter speed, you won't see any numbers like 1/1000 or 1/500. Instead, only the denominator displays. A shutter speed of 1/60th of a second displays on your camera as 60.
Since fractional numbers don't display as fractions, very slow shutter speeds use a special notation - a quote mark. A shutter speed of 5 seconds will display as 5" so that you don't confuse it with 1/5th of a second which just displays a 5.
What you should see here is that the shots at high shutter speeds are clear: neither subject motion nor camera motion causes any type of blurring. At 1/30th of a second, motion blur will be evident in some shots but not in others (it will depend on how fast the subject and/or camera is moving). At 1/10th of a second you should see quite a lot of motion blur - in fact, your entire image will look blurry due to the slight motion of the camera when you hold it in your hands.
Other Photography Sites
Great Photo Blogs
Recommended Digital SLR Retailers(These are the three online stores that I use to purchase all of my digital SLR photography gear)
In ConclusionFor the past year, my wife has been hard at work collecting information and photos about hundreds of parks within the United States.
While a lot of the information on the site is California-centric - a purely geographical limitation - she is willing and able to post information about ANY park, regardless of where it is located within the U.S. (she's not QUITE ready to go global yet).
If you happen to have kids, and if you happen to take them to parks, here's an opportunity to not only practice some of the techniques that I describe in this newsletter, but also to help others discover great parks in their neighborhood. Families on vacation can also use the site to discover safe places where their kids can burn off some steam.
Anyone interested in submitting a park - photos are required! - can do so using this page. My wife would certainly appreciate your suggestions and expanding the number parks on the site will be useful for many future visitors.
If nothing else, look at this as a good excuse to get out and use your digital SLR camera!
--Chris Roberts, Your Digital SLR Guide
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