Wednesday, April 22, 2009

Mastering Modes and Metering (or "The magic stuff your camera does")

Now that you've spent some time with your camera, you've probably
noticed that big dial with a whole bunch of symbols on it. Maybe
you've even read the manual (smart cookie) and used some of the pre
programed modes for something like sports or macro.
All of these program modes can be used to simply make your life
easier, or to give you more control over how your photos look. We'll
look at exactly what those guys do a bit futher down.

Camera Modes

There are three other modes available on many compact cameras and all
dslrs which are very useful. These are Av, Tv and M, or respectively
aperture priority, shutter speed priority and manual modes. The first
two are "semi auto" modes. You can fix one or two elements of
exposure, and the camera will automatically adjust the final element to
achieve an exposure based on the ambient light levels. For example in
aperture priority (Av) mode, you would select an F stop, and optionaly
an ISO, and so the camera would select an appropiate shutter speed for
a correct exposure. In shutter speed priority, you would select a
shutter speed, and the camera would adjust the aperture to an f stop
suitable for the ambient light.

There are a few standard modes that you will see on most cameras, including "auto", macro, landscape, sports and portrait.

Auto mode: This basicly turns the camera into a ol' big point and shoot. It's useful for when someone else needs to take a picture with your camera, and doesn't know the first thing about photography, but offers you hardly any control over how or where the camera exposes. Just press the button and the camera figures out the rest. It's ok to spend some time in this mode when you're learning how to use your DLSR, but mastering some of the other modes it gives you will help give you more control over your photos.

Sports mode: gives preference to a high shutter speed to freeze fast
moving objects. It does this by opening up to a wide aperture and
increasing the ISO to allow a typical shutter speed faster than 1/1000
of a second.

Macro mode: sets the preferred focus point to the closest object to the
lens. Useful for capturing fine details of a scene and small stuff like insects or flowers closeup..

Portrait mode: sets the aperture to a maximum value(decreases the F stop number) , to minimise the depth of field. This turns the background into an abstract blur, bringing attention to the subjects face (the focus point) which is sharp and clear.

Landscape Mode: Stops down the lens (increases the F stop number) to maximize depth of field, so you can capture a scene with the foreground and background in clear focus. Think about a mountain scene with some flowers in the foreground - using this mode, you could keep both parts of the picture clear and sharp.

Metering Modes

Aren't these cameras smart? Well if you have ever taken a picture of a
snowy scene you will appreciate how easily they can be fooled. See, to
figure out the exposure, the camera uses one of a few
different tricks called "metering modes". The simplest metering mode
is an average metering, where all the brightness of all points in the frame are just
averaged and the exposure set to make that average a shade of
"middle" (18%) grey. This works pretty well for a lot of scenes, but
is pretty easily fooled. For example, a person set against a white
wall will have a much lighter average value than the 18% grey. So what
will the camera do? Try to underexpose the picture so the white is
much closer to that 'middle grey' value. Of course, we really want an
exposure based on the subjects face, and the wall to be much brighter
than middle grey. So what are we going to do?

The easiest solution in this situation is to use another metering mode
called " spot metering". This metering mode bases the exposure on a
very narrow feild, a roughly circular 'spot', in the center of the
frame. Using this metering, the exposure can be set to the subjects
face, letting the wall be exposed to white. Voila.

Another very common metering mode is "Centre weighted", which is basically a hybrid of spot metering and average metering. The brightness in the middle of the frame is considered 3 or 4 times more important than the parts around the edges of the frame when determing the exposure. Again, in most situations this will ensure the subject has a good exposure, but will also try to not horribly over or under expose the other parts of the image. Either this or spot metering is a good option when your subject is going to have a very different exposure than its surroundings.

Perhaps the most commonly used metering mode is "Matrix Metering". No, it's not related to the enslavement of the human race. The camera measures the exposure at several points in the scene, then does it's little magic tricks to figure out the best exposure based on those points. Thats a pretty vague explaination, but it can vary from camera to camera in exactly how it determines that exposure, and can do so somewhat unpredicataby. However, it will tend to produce the most accurate exposures under most situations if you're not sure where to base your exposure around. Think of it as the "Auto" mode of the metering systems, you don't really think about exactly how it figures it out for you, but it will get it right most of the time.

One other thing worth knowing about the automatic metering modes is the EV or "exposure compensation" function. Sometimes, you'll notice the camera consistantly under or over exposes some types of scenes, even in matrix metering. The classic example is a family shot against a snowwy background - the camera sees all that bright white snow, and tries to dull it down. Problem is, now you've gone and underexposed your subjects.

EV allows you to tell the camera "you need to expose this scene so it's one stop brighter than you would normaly" by dialing in 1 stop of EV. A -1 EV would darken the cameras automatic exposure one stop. On low end DSLRs adjusting EV is often quicker and more intuitive for some people than changing metering modes, so do consider it as an alternative when adjusting exposure.

There you have it, you now know how to control your cameras automatic expsoure functions, and pick the best modes for your subject matter. Pretty neat, no? Now get out and take some pictures, but don't forget to keep on licking.

Saturday, April 18, 2009

Elements of Exposure: Digital camera basics

Exposure is one of those photographic skills that is fairly simple to learn, but hard to master. You will have most likely heard people talk about exposure in the past, probably in realation to a picture being under or over exposed. Exposure is essentially the amount of light recorded by the sensor, which will essentially determine how light or dark your image is. Too high an exposure, and you will be left with a blown out, blanket white picture. Too low and you will be left with an empty black image. Modern cameras can determine a proper exposure for a picture automatically, with a nifty little device inside them called a light meter.

But firstly, how do we control exposure? Every camera has 3 elements which are used to determine exposure.

1. ISO (or how sensitive the sensor is to light)

2. Aperture (or how much light is let through the lens)

3. Shutter speed (how long the sensor is exposed to light)

Each of these will have an effect on both the exposure, and the "look" of the picture.

Lets start with...


ISO is a measure of the sensitivity of a photographic film. ISO itself stands for "international standards organisation", which created a guideline for film sensitivities worldwide. Despite being grounded in film technologies, digital cameras have an adjustable ISO. A higher ISO will make the sensor more sensitive to light, almost akin to a volume control on a stereo. Using this example, turning up the ISO in a low light situation is like turning up the volume for a very quiet song.

However, this has a side effect. A higher ISO introduces more digital noise, or "grain" into a picture. Click on the image to the left to see how grain a high ISO has made it.

High ISO also reduces dynamic range (how dark or light the shadows or highlights can be while maintaining detail). A high dynamic range is particularly useful for salvaging shots with computer software if the exposure is wrong, often called "exposure lattitude".

Sometimes shooting with a high ISO is unavoidable, but generaly I like to shoot with the lowest ISO I can for the clearest shots with the most dynamic range.


You can think of aperture as "how big is the hole in the lens", or how much light can get through the lens. It's measured in F stops, where a lower F -stop is equivalent to a bigger hole, and a brighter exposure.

So, for example, a picture taken at F8 will be brighter than one taken at F11 if the other settings are the same.

Aperture is very important for one other reason - it controls the depth of field of the picture, or how much of the picture is sharp. A higher F stop will have a larger part of the picture in clear focus.
See how most of the image is blurred, and only a small part around her mouth and nose is in sharp focus? That's because this photo was taken at F2, a rather low F stop. This gives some cool creative control over pictures, because now we can direct our viewers eye to a small part of the scene, and abstract everything else in background blur. Or we can increase the F stop, and get a larger part of the scene in clearer focus.

Shutter speed

Finally, we can control exposure by controlling the length of time the sensor is exposed to light. The longer we leave the shutter open, the more light is allowed to fall onto the sensor.

Shutter speed can vary from hours to a 10000th of a second, but typicaly are between 1/2 a second and 1/4000th of a second. A photo is never taken in an instant, only ever over the time the shutter is open. If you're shooting at a 4000th of a second, then you're recording everything that happens in that 4000th of a second. This is pretty neat, because not a lot changes in that type of timeframe. So it's possible to 'freeze' fast moving objects with detail we cannot normaly see, like water droplets splashing.
On the other hand, a longer shutter speed allows thing to move during the exposure. A common use of this is to keep the camera steady on a tripod, and record moving objects as a blur.

In this photo, the water is trickling while it's surroundings are stationary. With a half second exposure and the camera resting on a rock, the sensor records the stream as a soft blur while it's surroundings (that are in focus) are tack sharp.

One other thing to note about shutter speed is camera shake. Hand holding a camera with a long shutter speed will introduce blur because of the camera moving in your hands. A good rule of thumb is to keep the shutter speed shorter than 1/(the focal length of your lens). So if you were using a 200mm lens, then anything faster than 1/200s should produce motion blur free photographs. At 1/100 s, you would risk introducing extra blur.


Ok, now lets put all this into use in a theoretical situation. Suppose using your cameras inbuilt light meter, you know that you will get a good exposure at 1/250 at F8, ISO 200.

However, being the creative genius you are you decide that you want to have a very narrow depth of field to blur out the background, and want to take the picture at F4 instead. No worries, just change that aperture to f4 and take a picture.... what do you know, it's white and washed out. Looks like we over exposed there...

By changing the aperture and keeping all the other settings the same, you've just let more light fall on the sensor and ruined that lovely exposure you had. So what are you going to do? Well this is where understanding "stops" come in.

Note that these are related to the "F stops" that we were measuring the aperture with, but are NOT the same. A stop is simply a relative measure of twice or half the amount of light falling on the sensor.

So if we have our exposure at 1/250 at F8, ISO200 and we were to decrease the shutter speed to 1/500 of a second, then the sensor would be exposed for half as long as before, so we would have decreased the exposure by one "stop". Halve it again to 1/1000th of a second, now we've dropped it 2 stops.
If we increased the ISO to ISO400, then we would have doubled the sensitivity of the sensor, meaning it is now twice as sensitive to light. Hence, we would increase the exposure one stop.

Aperture and F stops

Because aperture is related to the area of a circle (how big the hole is letting the light it) it's numbers work a little differently. Multiplying by the square root of two (around 1.4) gives you an aperture one stop darker.

So some common aperture values,

F1.4 F2 F2.8 F4 F5.6 F8 F11 F16 F22

(each of these is one stop darker than the one preceding it)

Notice that looking at every second number above, the F stop doubles. So, if you double the F stop (for example F8 to F16) then you have actually decreased the exposure 2 stops.

Going back to our original example, if we've gone from F8 to F4 we have actually increased the exposure 2 stops. That explains why that photo was overexposed... So to get an "equivalent exposure" we need to adjust the ISO and shutter speed to cancel out those 2 stops. We can decrease the shutter speed from 1/250th to 1/1000th of a second, which will decrease the exposure 2 stops. The two will cancel each other out, meaning our sensor is receiving exactly as much light as it was with out original exposure.

Understanding exposure can be daunting when just starting out, but its a fundamental tool in photography. Give it a little while and it'll be second nature when you pick up a camera.

Friday, April 17, 2009

The Gear - DSLRs Vs Point and Shoot

So, you want to get started in photography.

I'm going to recommend that you get a camera...

Ok, it sounds obvious but things get tricky here. Spend any amount of time involved in photography, and you will quickly see how people will not hesitate spending absurd amounts of money. That said, photography can be as cheap as you're willing to be creative.

So what is a camera? A camera is a lightproof box designed to record an image.

That's all.

Lets have a look at two examples of this....

Take a look at the Nikon D3x, a top of the line SLR:


24.5 Megapixels, Price: ~ 8000 USD, plus a lens.

Schnazzy, no? But a little on the pricey side...
On the other hand look at a camera 100 times cheaper, the Canon A470Photobucket
7.1 Megapixels, price: $80 USD

Now if you were to take the D3x, and put it right next to the A470, and take a picture outside of a sunny field with each, take the results down to your local camera shop and get some 6X4 prints done, there would be very few notable differences.

This would depend on which lens was on the D3 too, but my point is this - a camera is simply a tool to a purpose. A camera might be able to produce higher resolution images(more megapixels), or more vivid colours, or sharper images (a better lens), but no camera will definitively "take better pictures" than another. Not anymore than a paintbursh will paint you better landscapes, a pair of sneakers will make you a better runner or a new car will make you a better driver. Some people can take the A470 and produce fantastic images, while others can take a D3x and produce piles of mediocrity. It might be sharp, vivid mediocrity but mediocrity regardless.

Case in point - Almost any photographer today would aspire to the quality of work by the great Ansel Adams. What camera did he use? Well, a hulking massive wooden box that few modern photographers would consider using for practical work. There's more technology in that $80 camera than he could have dreamed would ever be used to make photos.

Most people are familiar with compact cameras (often called "point and shoots") like the A470 already, so I won't go into the details of their operation too much. However, I will say if you're trying to develop your photography as a hobby then you should look for a model that has manual (M), shutter priotity (Tv) and apeture priority (Av) modes, and an exposure compensation (EV) function is also very useful, though it will most likely be buried in menus somewhere.. These are modes that are on all "professional" SLR cameras and will give you much more complete control over how the camera works, and using them will help you understand how exposure works.

But mention photographer to the casual observer, and they probably think of someone with an expensive big black camera like the D3x. These are called SLR or DSLR cameras (which stands for [digital] single lens reflex). This is just a fancy way of saying they have a mirror in them which allows you to look through the lens and flips out of the way to take the photo.

If you're paying more than $500 for a camera you should expect it to do a little more than it's little sibblings. Here are some of the advantages of DSLRs over point and shoots:

Interchangeable lenses

Unlike point and shoot cameras, the lens that projects the image onto the sensor can be swapped. This has a few good things about it. By using different lenses, you can get a different field of view. Shorter focal lengths mean a wider view, while longer focal lengths give a narrower view and a more "zoomed in" image. If you are particularly interested in one area of photography, you can get specialist lenses too - a macro lens for extreme closeups, or a fisheye lens for shooting extreme sports with an unusual perspective
Bottom line - You can use different lenses to suit you, your style and your subject

Ease of use

When you look at the back (and the top... and sometimes the front) of a DSLR you will see a whole bunch of snazzy looking switches, dials and buttons. Contrary to popular belief, they are not there just to make the photographer look smarter. A serious DSLR is designed to have all of the commonly used, and most of the not so commonly used, controls accesable at the flick of a switch. This saves time digging through onscreen menus, which becomes very important if you're being payed to take photos of a kid that will only sit still for a second, or trying to get that car going by 170km/h. Though it may look daunting at first, with some learning an DSLR will become easier to use for creative photography.
Bottom line - You can change more settings quicker.

Bigger sensor size

When it comes to sensors, bigger is better. In a point and shoot, the digital sensor which records the image file is typically the size of a pinkie fingenail. A sensor that small heats up quickly, and when these sensors heat up a lot more noise (grain) comes out in images. A bigger sensor in a typical crop DSLR is a little larger tan a thumb print, so the heat is distributed more, and dissipates faster. Bigger sensors can also take advantage of better designed lenses, allowing for sharper images.
Bottom line: You get a clearer image.

Shutter lag and startup time

Point and shoot cameras have come a long way in this regard, but even now many have a noticeable gap between pressing the shutter button to take a picture, and the image being recorded. If you've ever tried to take photos of fast moving objects, you'll probably have noticed this. On a DSLR the shutter lag is minimal, to the point of not being noticeable (less than a tenth of a second). Also, the startup and focusing time is much faster - one you hit the power switch, the camera will be ready to take a photo in around half a second, as opposed to 2-3 seconds for a lot of point and shoot cameras
Bottom line: It's easier to capture fast moving objects or spontanious shots.

Pretty neat eh? Well why doesn't everyone use these things all the time? There are some less touted downsides to those big, expesnive looking cameras -

They're big

There is no way you're going to slip that Dx3 in your jeans pocket. If you're looking for some spontainous family snaps while out and about, size might be a problem. If you're looking to travel the world out of a single suitcase, size might be a problem. If you want to take your camera where ever you go, then be prepared to start carrying a backpack everywhere too.

They're expensive looking

If you can't just wack that camera in a jacket pocket easily, then you have to look at another option. To protect their camera, and keep it on eaily accessable a lot of photographers will hang it on a neckstrap, or in a purpuse built camera bag. Problem is, now you have a sign over your head that "I have a piece of equiptment on me worth between $800 and $8000". Camera bags are often targeted by theives in airports. Personaly I have been lucky enough to never have gear stolen, but it is always a possibility. That said, gear can be insured if it's a serious worry.

They're actually expensive

You should be prepared to spend $6-700 on a new DSLR setup. Thats with a kit lens, a bag, lens cleaner, and a cheap tripod. If you hunt around for an older model in good condition (which will do the job just fine) and some second hand lenses, you can get the bare bones for under $450, likely without a bag, tripod or cleaner. Another lens will give you more focal lengths to work with would be anywhere fromm $200 - $2000 depending on your needs. After that, you will likely want to get your camera and sensor cleaned once a year if changing lenses regularly (dust gets inside the body), at some point those shiney pro lenses will look very appealing (but not to your wallet) and you will find all sorts of ways you'd love to drop money on this new toy of yours.

You need will need time to learn to use them

Yes, you can put a DSLR on full Auto mode and come up with a slightly higher quality point and shoot camera. However, you will need to spend at least a bit of time understanding the camera and it's technology beyond "This button takes a picture". If that bothers you, then a DSLR is probably not for you.

Another important consideration for a casual user is the fact most DSLRs will not record video. Some are emerging with this capability now along with a live view.

Also, increasingly there is crossover between the two classes. EVF (electronic view finders) will look deceptivly like an SLR, but have an electronic display in the viewfinder and a fixed lens. Some of these can cost over $800, and at in my opinion at that price point a DSLR is a far more versitile investment.

So the final verdict? If you are serious about photography, seriously consider investing in a DSLR straight away. It will give you the opportunity to learn the most the quickest. If you're uncertain, don't discount a point and shoot.

For now, lick onwards folks.

Looking at Licking

Welcome to The Lens Licker, a place to learn about digital photography.

I bet you have a plethora of questions about digital photography. How do I take better pictures? Whats the difference between IS and ISO? Who on earth would actually lick a lens? How do I take sharper pictures? Are drop bears as dangerous as my Australian friend says? Wouldn't licking a lens be a bad idea?

I'll tell you now, the answer to the last two is a resounding yes.

I began digital photography about 18 months ago. I make no claims to be inspiring or professional. But I remember what it was like entering the digital realm, and I want to pass on what I have learned in those 18 months to anyone who cares to read. I'm going to start from the ground up. Some of this will be written as I learn it, because I never plan on stopping learning.

To see some of my work, have a look at or

For now, keep on licking.