Photography 101 - camera modes

[smilodon]

I was recently asked by a friend to write a piece about photography for a private forum he runs. I'm reposting it here on the chance that someone might find it useful. It's fairly basic so if you're already a keen photographer you might not find anything here of use. But if you're looking to move away from just using full auto settings on your camera this post might be more useful to you.

Get out of Auto Mode

Every camera has an auto/programme mode. From the lowest spec' camera phone up to the mighty Nikon D3 or Canon EOS-1D, all have this setting. Auto means just that. You point the camera at the subject, the camera checks the light levels, adjusts it's settings and takes a decent photograph. But you're not really doing anything other than deciding what to point the camera at and when to press the shutter. The result is in the hands of the designers of the camera, not you. It may be good but it might not. It might be rubbish. And it's at this point that you either shrug your shoulders and say 'that's as good as it gets' or move your photography forward a step and take more control of what you're doing.

Not all cameras have more than the single auto mode. My HTC Desire just shoots for me and there's nothing I can do about it. But many point and shoots and almost all DSLR's have at least three other settings. And it's these settings we're interested in. Now some cameras will have more than three. They'll have lots of settings like sport, landscape, portrait, night time etc.  These are actually auto modes but tweaked for specific types of photography such as the ones mentioned i.e. sport, landscape etc etc. We're interested in three settings common to all decent cameras, aperture priority, shutter priority and manual.

The techie bit. When the camera adjusts itself and takes a picture it is changing two settings, shutter speed and aperture. Shutter speed is the amount of time the shutter is open and aperture is the size of the hole through which the light enters the camera. The correct combination of shutter speed and aperture allows in a specific amount of light into the camera. If the camera does it's job right then the amount of light it lets in is exactly the right amount to get a nice exposure and a decent looking shot.

:sad::doh::blink: Sadly the way cameras display shutter speeds and apertures is a mess. It's a throwback to olden times when we had shillings and farthings and quarts and furlongs. Photography was just the same with a crappy system for labelling shutter speeds and apertures. But here goes for the simple version

Aperture goes up and down by doubling and halving the size of the hole in front of the cameras sensor. This obviously halves or doubles the amount of light that entered the camera in any given amount of time. We display the aperture as an f number. F numbers run as follows f1, f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f32. So f4 is twice as big as f5.6 but half as big as f2.8.

Shutter speed is easier. Whole seconds are shown with a " after them, so two seconds is 2" and four seconds is 4". Fractions of a second are odd as early digital camera displays couldn't show 1/2 as a value so the designers just went with 2. Therefore 2" is two seconds but 2 is one half of a second. Either way like aperture shutter speed halves and doubles as it rises and falls.

An example of a correct exposure might be that for a given scene a shutter speed of 1/500 at f8 aperture gives a decent exposure. As mentioned shutter speed increases or decreases by doubling or halving it's value. So if I move the shutter speed setting on my camera up one level I will double the speed to 1/1000 second. This means exactly half as much light has entered the camera and I'll get a dark underexposed image. However the aperture can also be changed by halving or doubling it's size. This in turns halves or doubles the amount of light that comes into the camera. So if I move the aperture setting up one level to f5.6 and make the hole twice as large I will double the amount of light entering the camera and make the image brighter. So I've halved the time and doubled the size. Half as much light (shutter) and twice as much light (aperture) obviously cancel each other out. So although I've altered both settings my exposure remains the same. Nothing has changed. As long as I change one setting to compensate for the other I can set many different combinations of shutter speed and aperture but still get the same exposure. As long as the same amount of light enters the camera it doesn't matter if that light arrives as a lot of light in a short period of time or a little light over a long period of time. It's all the same in the end. Or is it?

Back to the camera modes. Lets move out of auto mode and into 'shutter priority'. This will appear as 'S' or 'Tv' on your camera. What this does it let you pick the shutter speed and then the camera selects the correct aperture to give you a correct exposure. Why would you want to set your own shutter speed? Well you might want to freeze your image and show it sharp and focused


(image from Motor Cycle News)

or you might want to blur an image to show movement.


(not my image, cannot remember where it came from, found on hard drive)

Jump into shutter priority and set 1/1000 second to get the shot of the motorbike but set 1/15 second for the waterfall. Now you can freeze or blur your shots and add creativity to the image.

Aperture priority, shown as A or Av, is a little more crazy. A property of the size of aperture is how much of your shot is in focus. With a very small aperture (f32 for example) everything from close up to the far horizon is in focus. But with a very large aperture (f2. then only a narrow strip is in focus. If you put your camera into aperture priority you can dictate how much of your image is in focus and how much is not. This can draw attention to your subject and blur the background away. You can then start to dictate what your viewer concentrates on.


(image courtesy of //www.photonet.com)

This shot of a football match (not mine) has the players in focus, however the fans behind them while not pin sharp are still mostly in focus as well. As a result the action is lost in a sea of colour and shapes. We don't know what we're supposed to be looking at. Bad picture.


(image â'¸ Greg Townsend 2008)

This picture of an otter was taken with a very wide aperture. If you look close you will see that while it's eye is in focus it's back is blurred and the rocks that are a foot or two behind it, are completely out of focus. Our attention is drawn to the animal with it's odd pose and not to the rocks and pebbles that surround it. The otter jumps out and takes our full attention. Good picture.

So we can set aperture priority and set wide apertures (f2, f2.8, f4, f 5.6) to isolate our subject from the surroundings. This is good for portraits or shots where we have a main subject we wish to highlight. Or we can set a narrow aperture (f16, f22, f32) when we want to shoot a landscape or scene with everything in focus right through to the mountains on the horizon.

Digital images are free. There's no film costs to worry about so it's simple enough to mess about and practice. Grab one of your kids/grand kids/friends and set a wide aperture for a nice portrait shot with no messy background. Or set a slow shutter speed and shoot them riding their bike or running about for nice blurry speedy shots. Muck about with aperture and shutter priority and see what you can do.

(manual mode to follow)

[DrunkenZombiee]

Awesome post!

Really good 101 for those starting out and for those who wish to get better at photography.



I am looking forward to the manual mode post/edit as I struggle to get the light metering perfect for background and foreground. In the end I have to use flash to pick out peoples faces when against bright backgrounds even in manual mode with the setting tweaked. The human eye is simply too perfect to emulate using a Lens and a CCD/film due to your brain post processing different parts of the image in real time to fill in the gaps and make sense of them. Rods and cones are also more sensitive than a CCD in terms of conventional sight and in particular colour representation (RGB vs CMYK and 7 colour printing is another topic to go into at a later date).

The same can be said about the white balance as this is something I have always left on auto and have corrected in post processing when needed. I don't really know how or when to use it on my 550D and normally by the time I have finished fiddling with the settings the moment is gone =(. Everyone will know all about this at the LAN when I had them all lined up for ages to get the settings right in Manual mode. I normally shoot in Av as portraits and landscapes is more of my niche. During the LAN it was in Av at f/2.8 on my zoom and f/2 on my 50mm prime all the time as it was so low light and there was no way I could get the 1/200 shutter speed that I normally would use for shooting people in good light. IS is your friend!

I might have to have a chat with you at the next LAN about some photography elements if you are attending, as I am keen to learn to take better photos.

The science behind optics is really cool and I am tempted to scan in some some illustrations or ripp off some jpg's which helped me to understand many of the fundamentals of what essentially is a pinhole camera where the hole size is variable.
I might make some illustrations later to avoid copyright issues to share with you all.

If there is interest I may put a post up on the science behind modern cameras such as how a CCD works (really cool how it actually works in terms of photons and crazy physics), what is a Bayer array and how does it differ from film or a sigma foveon camera with a prisim and 3x CCD's for R G and B. This helped me to understand why 18mp is not actually 18mp on most cameras due to the averaging across four pixels on the CCD.

All of this is great to know of course but the best photos are taken by creative people and not geeky people such as myself. You don't necessarily need to know how something works to use it well =).

<\nerdy ramblings>

DZ

[Jamin]

Thx for that, I'm a point and shoot picture taker, but my camera has those options you mentioned to mess with, so I've learnt a little today :thumb:

[smilodon]

Cheers. I'll be at the LAN this year certainly. I know enough about the technicalities of cameras and photography to know I don't know much at all.
You could write books (obviously lots of people do) about all the aspects of photography, such as colour control, flash photography etc etc. The web is brimming with resources to check out.
I've written a couple of these post for my friend, one about composition and one about flash guns. I might add them here if people want, although the flash photography post isn't very good IMHO.

[Blunt]

Keep em coming smilo, very informative