Simon's Guide to Photography

[Guest]

Okay, with the photography walk coming up on Sunday I thought it would be nice to put down a few suggestions on things to think about. I know one or two who are not able to make it also expressed interest so potentially there might be some benefit to others. Doubtless many will already know much of what I am going to put here, but others might not.

Anyway, let's set the record straight first. I am just organising this Sunday, it's Paul and Bruce that are the experts and them that should be listened to. Unfortunately I think they are both a little busy to type up a huge illustrated post like this so you'll have to make do with me (!) and perhaps Paul, Bruce or indeed any of the other accomplished photographers on here (where's Clive when you need him?) can correct the bits I get wrong or leave out altogether. I'll probably break this up into more than one post or it'll be very hard to read.

COMPACTS and SLR's

Many of the people coming this weekend will have compacts. Don't make the mistake of thinking that what appears to be a simple point and squirt is not capable of producing good pictures if used properly. The person pressing the button is the single most important ingredient here - give a great photographer a simple P&S and they'll still take high quality shots, and correspondingly the reverse will also apply. Obviously though, compacts are more limited so I'll try not to labour too much on some issues which can really only be achieved using an SLR because it won't be relevant to many people reading this.

PHOTOSHOP

It's also important to note that I am going to leave out the Photoshop element of modern photography. As an inhabitant of many photography forums I frequently see breathtaking images posted up which make me insanely jealous. It was only after a while that I began to realise most of these barely qualified as photographs at all as they were created as much as they were shot. Sometimes the photographers posted the originals alongside the finished product and frequently there was barely any resemblance, a fact with which I bored poor Roy (boaters) with at length at the meet last Saturday. Frequently people seem to be taking an approach of set the resolution up to maximum, shoot approximately the image you're after, then get it onto a computer, crop it to the actual picture you wanted, adjust the colour hues and saturation, set the required sharpness, blur or erase things you don't want and hey presto, one magnificent picture.

So it's cards on table time - I'm an old fuddy duddy. To me the above owes more to graphic design than it does to photography and it's photography that I enjoy. I can use Photoshop (or rather Fireworks in my case), not brilliantly, but I can use it. And I'm colourblind, so playing with colours is a bad idea because I'd probably not notice if I inadvertently turned the cat purple. I almost never do any post-processing, or even cropping, 99.99% of anything I print is straight off the camera untouched. I also shoot only JPEG (I expect Paul and Bruce shoot RAW) so I'm also going to touch a little on how things have changed since the advent of digital cameras.

Are you still with me?

One last thing, rather than just rabbit on I'll try to illustrate what I mean with some of my own pics - but as I already pointed out, I am no photography genius so expect example pics, not works of art. Even worse, for reasons too complicated to explain, the only set of pics available to me to take examples from mostly hail from 2006 and with the odd 2007, the rest are elsewhere and I cannot get to them at the moment so I had a limited pool to choose from!

Posts to follow:

1. DIGITAL vs FILM

2. FRAMING YOUR SHOT, including angles of view

3. EXPOSURE, SHUTTER SPEED and DYNAMIC RANGE

4. GOING FOR EFFECT

Lastly I'll do a post on Depth of Field (DoF). That's actually one of the most important things to understand with SLR's but I've put it so far down the list because with compacts you have little ability to manipulate DoF.

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DIGITAL vs FILM

In order to get the best from your camera you need at least a reasonable understanding of how it works. That way you can have an idea of how it might behave in given situations. As a foundation to this, let's start by looking at what happened as digital began to displace film as the principal medium in consumer photography.

For me it is still the case that for out and out quality film is still where it's at, even in 2008, but for sheer versatility, creative freedom and all round convenience it's digital all the way. From 01 Jan 2006 I've been 100% digital. With film, many elements come together to make the photograph that you end up with. A number of the properties of the picture will be determined by the film itself and then later in the development process. Digital can bring together all the stages of what was once a multi-stage process but whilst this is useful and provides a greater level of on location control, it also means there are more things you need to understand.

As an example of how things change, imagine you went back in time and you spoke to someone from say, 1980, and waved a memory card at them saying that in 2008 this was what cameras stored images on. A logical question from 1980 man would be to ask how many pictures you can store. But the answer to that is actually very much more complicated than the old days of film - it's not a case of like for like where a film could hold 24 or 36 frames. The answer here depends on the size of the memory card, only they are all the same - I mean a 64Mb and 4Gb CF card would look identical but one can store very much more than the other. And then there's the resolution of the pictures, the compression level of the JPEG's, the colours and subject matter of actual frames. The real answer is keep shooting until you run out of space to give an exact answer before taking any shots is impossible because digital plays to different rules when with film it was simple - X length of film has space for Y amount of frames. Not any more.

The same is true in other areas. Many aspects of film photographs were dependent on the film being used. I seldom used Kodak Gold because, although sharp, the colours were generally dull. My preferred film was always Fuji Superior which produced brighter, more pleasing colours. And I tended to use ISO400 film because of my preference for long lenses, the faster film gave me an extra stop of light (in other words worked better in poorer light and allowed faster shutter speeds in better light). A lower speed of film, such as ISO100 or ISO200, would have been more limiting. The trade off was a higher "grain" effect in the resulting images. But with the advent of film all this became just another camera setting, or rather a group of different camera settings.

ISO

This is straight forward and easy to explain - it dials the sensitivity of the digital sensor up and down to deal with different lighting levels; more sensitive means you can shoot in lower light. But like film the trade off is in "grain" or rather "image noise" as it is with digital sensors, basically a manifestation of electrical interference which the sensor becomes more sensitive to the more you turn their sensitivity up. The resulting image noise looks much like the grain of film in the resulting picture. ISO will normally only need to be set once at the start of your shooting and lower (ISO100) is better. If you dial up the sensitivity you will increase image noise so only do it if the light is not good enough to allow good shooting at ISO100 or 200.

White Balance / Colour Saturation

These are two further adjustable settings in digital which would once have been determined by the film in your camera, not by the camera itself. To an extent the camera replaces not only the film but the darkroom with these two. Digital shooters who use RAW can largely ignore these and will determine the desired levels at the post-processing stage, i.e. when they are manipulating the shots on the computer. It is only then that you get the finished product. When shooting JPEG the camera is effectively doing the whole darkroom job itself as it creates the finished product then and there. This is when white balance and colour saturation become more important so understanding what they are there for can help you escape the confines of AUTO mode and start taking more control of your pictures.

White Balance

The camera is made up of many components but the principal ones of interest are the lens, the sensor and the processing engine. The processing engine is the biggest change from film to digital.

Your eyes see, they focus and they let in light and your retina captures the image - but it is your brain which processes it. The lens and sensor are the eye, the processing engine is the brain when it comes to cameras. But it's not that clever and the more information you give it, the better picture it will produce. The white balance presets on your camera tell the brain what the prevailing light is like and helps it produce the most accurate final image that it can. Generally you'll see presets for:

Sunshine / Cloud / Incandescent / Fluorescent / Flash

All these do (in simple terms) is inform the camera's brain that when it receives the information from the sensor it needs to apply a set of rules shifting how it draws the final picture to allow for the fact that white might be slightly grey if shooting in cloud cover, or slightly yellow if shooting under incandescent tungsten lighting and so on. White, and all the other colours, are then adjusted accordingly to produce a colour-accurate final image. It's not perfect, but it's better than letting the camera guess in AUTO mode. Generally WB only needs to be set once per session, not normally changed with each picture, though obviously the sun can go in and out, and you can walk into buildings and therefore to electric light etc.

If you're used to shooting AUTO, but you start using P mode instead, where ISO and WB are usually used defined, at first you will probably make some mistakes and forget to change it. I know when I got my first digital compact camera in late 2003 (indeed, most of the example shots in later posts from that very camera) I got quite a few strange colour casts on my pictures at first because I kept forgetting to check WB. But the more you use it, the more you get used to it.

Colour Saturation

This is simply how strong the colours are. The more saturated they are, the brighter and stronger they are. Unfortunately bright strong colours have become a bit of a consumer gimmick because they are eye catching. The fact that hammed up colours are often not a very good representation of the actual scene shot is easily ignored if it boosts unit sales. If you are a more discerning photographer, and your camera has a tendency towards over-saturated colours then you will usually find there is a setting to tone it down a little. This is the kind of thing you will need to determine your preference but once set should more or less never need to change again.

Sharpness

This is another aspect which has moved from film / darkroom to an on camera setting. Again, consumer compacts often sharpen up images quite strongly. This has a wow factor and undoubtedly looks good on computer monitors but often it can detract from the printed photograph with unnaturally sharp edges which can look jagged particularly on straight oblique lines. Again, find the level which works best for you and once set you should probably never need to change it again. If you don't print much, sharper (to a point) might be better, but if you like photo albums and particularly if you enlarge prints you might find settings which look good on screen don't look so good on paper. SLR's, traditionally the territory of more experienced photographers, generally produce softer looking images and this is the reason why. Indeed, when I first bought a dSLR I was disappointed with the on screen results but the printed results are something else.

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FRAMING YOUR SHOT

So, now you understand about ISO and White Balance (WB) you can move the dial from AUTO to P on your camera, or whatever the corresponding mode is. In P mode you get to choose things like the ISO and WB for yourself, but the camera will still do the metering and choose the shutter speed and aperture settings for you. Many people never move beyond this mode and, to be honest, for the majority people you will probably never need to. But no matter whether you do or don't, if you cannot frame a picture properly you will never really get great results - nothing bar nothing is more critical to the final shot than composition. Of course, it is always possible to crop the shot on a computer but when all it takes is a little thought to get it right in the first place, why make so much extra work for yourself?

Framing is partly personal taste, and different people will have a different take on how best to frame a given subject. I hope that is one of the things which comes out on Sunday - we will all be looking at the same things but people will have different ideas on how to frame them and may think of things other have not. So I apologise if I hold forth on personal taste but there is bound to be some element of that.

Example pic no 1 from my 2003 compact (taken in 2007)

One of the most common "mistakes" when shooting people is a tendency to put their eye level in the centre of the shot. Most of the time that produces images where nearly half the picture is sky or background and the subjects are sliced off at the knees or ankles. If you are trying to take a picture of a group of people like the one above, you need to aim the camera somewhere in their middle and watch the top and bottom of the frame to ensure you are not cutting off heads and feet. In the picture above I was also trying not to cut off the end of Angela's wedding dress so I made a little extra room for that. Just paying attention to these little details can help produce a much better shot - and no amount of post-processing will return missing limbs!

Generally, if you can, you want to get the subject somewhere near the centre of the frame (advanced photographers will talk about the Rule of Thirds but we'll just deal with the centre here) and try to avoid distracting clutter getting in. Don't be afraid to use the zoom facility, most digital compacts have 3x or 4x optical zooms. If you have a digital zoom it's probably best to turn it off and pretend it doesn't exist - some cameras handle digital zoom better than others, but generally speaking don't go there. So if you can't get close enough to make the subject fill the frame, zoom in to it. Or if you are trying to set the scene and include "the bigger picture" so want to feature a little of what's around the subject try to position yourself so if there is anything unsightly around the subject you can cut it out, or at least minimise its impact. Furthermore, if the subject is tall, rather than wide, do not be afraid to turn the camera on its end as in the example below taken in 2007 on my compact, which shows the front of Merton College Oxford. The building was much wider than this, but it was this centre section I wanted to concentrate on so I framed it accordingly.

Lastly, even if you do want to include some of what is around the same subject, make sure you don't make the subject too small - remember, most albums are 6x4 which is not that big. If the subject is tiny when you're looking at it, it's going to be very small indeed if it merely fills the centre section only of a 6x4 print. The example below, shot by my wife with the same camera, was a reaction to a scene rich in detail and colour, the original "a picture speaks a thousand words".

Angles

When time and space allows, one advantage of digital is that you can snap away merrily with using up screeds of expensive film. If you are faced with a possible range of different angles and are not sure which one to choose, try several different ones and later on you can decide which one worked best. Try to be creative here too, if something doesn't come off, all you have to do is delete it. I am sure Paul will testify that for every shot he sells as a pro there will be dozens, maybe hundreds, which just get binned. Below is a range of shots taken by a friend of mine on his (cheap) compact in 2006.

He was just experimenting to see what worked best. I dare say in any group of people each picture will be the favourite of somebody.

Another example I can illustrate using this shot I took in 2006 on my SLR of the first time an Airbus A380 touched down in Britain (see below).

I was there to record the arrival of the aircraft and I did a middling job at framing a fast moving object. Behind me was a professional photographer for The Guardian. He asked me if it would be okay for him to take a picture of me taking a picture of the aircraft to be published in the newspaper. I said fine. A moment I turned round and he was gone - but wait, no he wasn't. He was actually lying on the ground behind me. He had decided the best shot for him would be looking up at me as the aircraft went overhead - a novel idea but it obviously worked because the picture was actually on the front page of the newspaper the following day (I don't have a copy to hand).

Some more examples of the above:

In the first shot, both on my compact, I deliberately wanted to capture the scene with the yacht in the middle, rather than just of the yacht itself so I didn't zoom in too far. The second was more of an attempt to concentrate on the yacht and capture the reflection and I nearly got it right (it's slightly off centre) but then I was trying to drive the boat at the time! It just illustrates two different ways to approach the framing.

One more reflection picture I like is this one, captured about 30 mins later. The boats in the shot aren't the prettiest, but the reflection was great so I tried to frame this as symmetrically as possible.

Finally a scene of the absolute tranquillity of the broads. I just knew I had to take this.

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I think it's obvious to all that none of the above pictures are breathtaking in their quality - I'm not that sort of photographer. What I shoot tends to be uncomplicated, matter-of-fact type stuff. There's no real magic to it, they are just honest captures of whatever I was seeing at the time and I guarantee anyone here with a camera of more or less any quality level could have done the same. As I have said before, I hope no-one coming on Sunday is coming expecting magic (unless Paul or Bruce provides it!) - we can't teach amazing photography, just solid "safe" photography.

Some other shots to consider the framing - this view of HMS Belfast, for example, taken on my SLR in 2006. I took the Belfast from countless angles that day, I happened to choose this one purely because it was not a "typical" shot. I rather like it.

Don't be afraid to get close to the subject either - Dillon didn't look like he was preparing to chew my face off in the shot below though I expect I still probably zoomed in from a few feet away. Again, I made sure here that the features of the cat went right to the top of the frame, rather than have his eyes bang in the middle, as some people might, and then end up with lots of pillow and wall filling the top of the frame. I didn't want a picture of pillow and wall, I wanted cat, so I framed accordingly.

[Guest]

Thanks Bruce!

EXPOSURE, SHUTTER SPEED and DYNAMIC RANGE

Okay, so we know how to set our white balance and ISO values, and we know why we do that. We've moved our dial from AUTO to P and we even know not to cut the feet off our subjects and to make sure we frame things as best we can under the circumstances. Now we let's have a look at what the A, S and M modes on that camera dial are.

EXPOSURE

Okay, to be honest, I leave my SLR in A mode for shooting pretty much all the time. But my compact seldom ventures out of P mode. Why? Well really by the time you are shooting at a level where you are playing with these things the gulf between compacts and SLR's starts to open up. The modes essentially do the same thing, but the SLR does it miles better. But that doesn't mean the compact can't do it at all - it would be a bit like fitting a race mode to my Ford Mondeo, it might make the car feel a bit sportier but it won't be like the race mode on a Porsche 911. Even so, there are occasions when it might offer you something the P mode can't.

A mode deals with exposure. Exposure is effectively how bright the picture is. The camera's metering system has to judge how much light there is in the scene you are about to shoot, and whereabouts it is located, and set a combination of shutter speed (how long the shutter is open for) and aperture setting (how wide the iris in the lens is open) which is capture the light level just right. Too short a shutter speed or too small an aperture and not enough light will reach the sensor so the picture will be dark. Too long a shutter speed or too wide an aperture and too much light will reach the sensor resulting in parts, or all, of the scene being a white out. Many combinations of the two will let in the same amount of light and so get the correct exposure, but the resulting photographs will be different.

In P mode, the camera selects the shutter speed and aperture to get the correct amount of light in. You set other items like white balance and ISO. In A mode the aperture is set by you. The camera then chooses the corresponding shutter speed to go with the aperture setting you have chosen. If you open the aperture wider the camera will compensate by choosing a faster shutter speed to maintain the same level of light hitting the sensor. The result for varying aperture is to control something called Depth of Field. I'll explain Depth of Field (DoF) in a later post so I'm not going to dwell on it too much now because there is little you can do on a compact to play with DoF. What you can do, however, is use Exposure Compensation.

Exposure Compensation is a way to prevent the camera from selecting the aperture / shutter settings to provide optimum exposure of the picture. You are effectively overriding it and requesting either a darker or lighter picture, depending on what you are hoping to achieve. There can be two reasons for this; one is that you are looking for an effect or two that you are aware the camera will get the metering wrong so you make adjustments to compensate for the camera's mistake. More experienced photographers will recognise when they see lighting conditions which will confuse the camera's metering system and will know when to intervene. Many people reading this might not, so for now we'll leave it at that. But the first one, adjusting the lighting for an effect, can be a powerful tool. Witness the following two photographs:

They were taken 14 secs apart. Back in 2006 I was staying at a B&B near Norwich station looking for houses and a job in the area. I'd had a meal at an Italian restaurant near the yacht station and afterwards I went for a walk along the yacht station and that was the sight that greeted me. Spotting an opportunity I took two shots on the camera's highest resolution but for the first I dialled the exposure compensation up to capture detail in the cathedral and then set it down several levels to try to capture the silhouette only and make the sky more vivid. As I said earlier, there's no Photoshop involved here at all, these are straight off camera - and you can see the two different effects. With the silhouette I was satisfied it had worked according to plan and the pic is now a framed 10x8 hanging up in our house.

SHUTTER SPEED

Again, playing with shutter speeds is something which works far better on an SLR, but compacts can do and in fact do it rather better than they can play with apertures. For this you need an S mode (Shutter Priority). In this mode you tell the camera the shutter speed and it selects the correct aperture to get the proper exposure. Although compacts often have a decent range of shutter speeds they are limited by the aperture settings. As you set one up the other most go down to keep the exposure the same. Generally compacts only have 4 or 5 possible aperture settings because they have small and simple lenses (many SLR lenses cost more than the SLR's themselves, much less a compact, so it's not surprising they are much more complex). That means you can only adjust the shutter speed one way or the other and maintain the same exposure or you run out of apertures, after which the pics will start to become too dim or too bright. Even so, the effects of differing shutter speeds are much more noticeable, even just a few settings one way or the other.

Shutter speeds, of course, determine how long the shutter is open and therefore how long the sensor gets to the see the outside world. The longer it's open, the more likely you are to see motion blur in an image capture. I took the following pic on my compact using S mode:

My aim was to track the old guy on his bike as he passed and have him in focus but blur the background a little to get the sense of movement. It sort of worked, mainly the problem was that he was actually going really quite slowly and, with the sun behind him, the camera was getting lots of light so it was not keen on using a particularly slow shutter speed. I took the following two shots on my SLR later the same year.

The pics are of the same duck (these are crops, btw, the only two cropped images I am going to use here). The first one I used a slow shutter speed to maximise the motion blur from the duck. It didn't really work, the shutter speed was so slow the whole duck was blurred and the wings almost invisible. The second shot was taken using a much faster shutter speed so the duck was captured much better, but there was still enough motion blur on the wing tips. I do have some better examples, now that I am at home and can get to my pics from other years, but I don't have time to use any others (I have tried but all the files Photoshop is saving are turning out to be corrupted and I cannot afford to lose any more time). By the same token, you can use very fast shutter speeds to halt high speed action completely, like the rotas on a helicopter or the spokes on a bicycle.

Now most cameras will have shutter speeds which last longer than 1 sec. Most people cannot take hand held pictures below about 1/40 second on wide zoom, quicker on longer zooms. If you try, you just get blurred images due to handshake. But with the use of a tripod, or indeed anything handy, you can get round this to get the effects you're after. Two examples here:

The first one of traffic in Singapore was taken on the compact, the second one of my old boatyard in Brundall was taken with my SLR. In both cases the camera was set down on a nearby object (bridge railings / flood defence respectively), the correct exposure was set by the camera and triggered by the self timer so I did not touch the camera at all and job it. The two effects are obviously quite different - the first one intended to show the motion of the traffic whilst keeping good detail in the surroundings, the second was intended to be entirely in focus and just capture the serene atmosphere in the boatyard that evening. The final one below was actually hand held and showed a joke Christmas present my mum bought me last year. It was a remote controlled car with lights on which could spin and do stunts and stand upright on two wheels. The shot was taken with the lights off and a slowish shutter speed of the vehicle spinning. Quite a cool effect I thought!

DYNAMIC RANGE

I won't say too much about this because it gets quite complex. However dynamic range is essentially the ability of a camera to capture a scene which contains both very light and very dark elements in the one shot. The camera's metering system sets the exposure but it can only choose one exposure level. It has to decide whether to shoot a lighter scene and have the highlights blown (i.e. white out) or a darker seen and have the shadow detail disappear in to pitch black. Or of course, it could go half way and have a little of either. This is dynamic range and unfortunately here, even the best digital SLR's are completely cleaned up by film. Digital imaging sensors have a poor dynamic range compared to film so difficulties with dynamic range are always likely to be encountered. Experienced photographers will recognise when the such lighting conditions are likely to be a problem - summer evening shots, for example, with a low bright sun and long shadows and particularly around water or GRP both of which will reflect brightly. So for Broads photography the dynamic range limitations of digital can be a potential problem. Film would do a much better job of retaining shadow detail without blowing the highlights, but then it comes with all the drawbacks of film so you just have to deal with it as best you can and things are getting better as technology advances.

When faced with a situation like this the experienced photographer will decide whether it is the shadow detail or the highlights that he or she is more interested in and, if the camera appears to be favouring the wrong one, or going for middle ground, you adjust the exposure compensation to achieve the desired result.

Sometimes, however, you might get a nice effect from dynamic range issues. Take this:

I liked the contrast of the setting sun reflecting off the boat to the right, the people looking thoughtful on the bow against the contrast of the long evening shadows. Different cameras do different things at this point. I shot a scene similar to this on a Canon EOS400D SLR and the Canon most definitely favours a brighter image with more detailed shadow. The flipside is the that the detail on the boat and the subtle variations in shade are lost as it because a white mass, blown out because the camera is trying to pick up the shadows. My Konica Minolta 5D SLR, on which the above was shot, always favours the darker exposure, losing shadow detail but preventing the highlights from blowing out, hence retaining detail on the boat. Canon is a much bigger name in photography circles and the EOS400D is towards the bottom of the SLR market offering so it's effectively the camera designed to take people from the compact sector and give them a leg up into SLR photography. As such the camera tends to favour the bright punchy images produced by compacts - much less so than the compacts themselves, but noticeably more so than the rather less popular and less consumer orientated (and now defunct!) Konica Minolta.

[Guest]

Now post Number 4 was going to be about going for effect but I've actually covered some of the examples I was going to use already, like the remote controlled car, the night time traffic in Singapore and the motion effect when trying to follow moving subjects. So I'll knock that one on the head for now and I'll move the Depth of Field post up to Number 4 and then Number 5 (probably tomorrow now) can be used to mop up general miscellanea that I've forgotten elsewhere or that did not comfortably fit into any of the other categories.

DEPTH OF FIELD

Okay, so I've left this until last precisely because this is something which compacts do struggle with so this one post is going to be much more useful to SLR users - however, that's not to say that it does not apply to compacts at all but there are certain things you need to do to enhance the effect.

So first of all, what is Depth of Field (DoF)? Well, in its simplest terms it's the amount of the frame in front and behind of the actual focus point which is also in focus. The following shot is not a great shot by any means, but it illustrates DoF.

Whilst the birds are in focus, the grass in front of them and behind is out of focus. Indeed, there is a clearly defined area which is in focus around the birds. The DoF refers to how large the area in front and behind the subject is also in focus (one assumes the subject will always be in focus). You can use DoF to make your subject stand out. Take these:

In both cases I have used a shallow DoF to throw the background out of focus and ensure the subject stands out in the frame. In the example below, a straight forward tourist snap from earlier this year, you can see that both Susan in the foreground and the Royal Palace in the background are in focus. After all, the point of the picture was to have Susan shown in front of the Royal Palace and if either of them was out of focus it would somewhat defeat the purpose of the shot - so I used a large depth of field with this one.

Rather than go too much into detail I'll try to find some higher level articles that explain the elements of physics which give rise to the effect of DoF. For the purpose of this post I'll just concentrate on how you do it - and how you do it is simple. Remember that A mode on your camera? Well this is aperture priority mode where you set the aperture and the camera chooses the corresponding shutter speed to get the right exposure. Aperture is what determines DoF. Small apertures, meaning the iris on the lens is closed right down mean large depth of field, large apertures, meaning the iris is open right up. Remember, the iris, and hence aperture, is there to control the amount of light reaching sensor. It is measured in F stops.

On an SLR most standard issue kit lenses (i.e. cheap) have a widest aperture setting of F3.5 - in other words this is as wide as the iris will go and will give you the smallest depth of field around your subject, normally portrait style photography. Typically the other end will be something like F19 or F22, though typically most people would not go below F16 as the performance of most lenses tends to fall off after this point. You'd normally use this more for landscape type photography. You'll often get better performance from the lens by going one stop down from wide open, so use F4 instead of F3.5 and you might get a sharper result.

Another thing to remember about DoF is that it changes with focal length. Focal length is how far you are zoomed in. If you are fully zoomed out DoF will be at its biggest but decreases the more you zoom into a subject even if you keep the same F number (aperture). So F4 at a zoom level of 200mm will give a much shorter DoF than F4 at 24mm. You might, therefore, need to vary the aperture as you change the zoom in order to maintain a similar DoF.

Compacts

Well compacts struggle with DoF. Their lenses are quite different and generally offer very few aperture changes, but the real key is that the image sensors are much smaller. This has a massive effect on DoF and means that it is almost impossible to isolate single subjects in the field of view and bring the DoF in to highlight them. Normally with a compact if the AF gets it right and your hands don't shake then the whole frame will be in focus - whether you want it to be or not. Even so, you can still just about get DoF effects with a compact, if you rig the photo accordingly. Many compacts still do have an A mode so select that, scroll to the widest aperture it will allow (smallest number). However, it probably won't be enough to get the effect, so here's the clever bit. Back away from the subject and stand as far back as is practical - then zoom in to get the same frame as you would have done stood right in front of them. Remember, DoF decreases as zoom increases so the more you zoom, the smaller the DoF becomes around your subject and the more likely you are to achieve that SLR style focus on one subject. You do actually increased DoF by moving away from the subject but your shrink by a much greater amount by using a longer focal length so the net effect is a smaller DoF overall.

I'll try to mop up anything I've missed out tomorrow.

Further reading on DoF here: http://www.amateursnapper.com/photograp ... -explained