A Little Photo Rules

8/2/2019 A Little Photo Rules

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Focal length

Visualise how focal length will affect the angle of view by imagining looking through a

piece of card with a 35mm wide rectangular hole in it: hold the card twice as far from

your face and you'll see half as much through it.

So doubling the focal length is just like cropping the photo to half of its width and

height and blowing up the result to full size, except without the loss of resolution that

would occur if you did that in Photoshop.Everything else about the picture remains

exactly the same.

A landscape at 18mm, the white box

marking 1/5 of the width and height

The same landscape at 90mm: the focal

length is 5 times longer so the area marked

by the white box fills the whole scene

Focal length and perspective: OK, backpedaling time. If two photos are takenfrom

the same position at different focal lengths, then the longer focal length photo will look

like a crop from the middle of the shorter focal length photo. However, often a

photographer will change position as she changes focal length. When you're shooting a

specific subject you will use a wide angle lens and get right up close to the subject, or a

telephoto lens and stand back; either way, the subject fills the whole frame, but the

perspective will look very different:

Using a wide angle lens means that the camera is much closer to the subject than the

subject is to the background. This exaggerates perspective and makes the background

seem small and distant. The reverse is true with the telephoto shot, which includes less

of the background while making it appear closer to the subject. This thistle was shot

with 3 different focal lengths:


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Stops and exposure settings: the basics

Adding one stop means doubling of the amount of light that the plate records.

The amount of light you record is controlled by the camera's exposure settings:

aperture, shutter speed and sensitivity. Opening the aperture by a stop or decreasing

the shutter speed by a stop or increasing the sensitivity by a stop all have the effect of

doubling the brightness of your scene.

Shutter speed

The shutter speed is considered an exposure setting because opening the shutter for

twice as long lets in twice as much light which increases the exposure of the whole

scene by a stop. However you can also use it aesthetically: faster shutter speeds freeze a

moving subject, slower speeds record a motion blur. Neither is 'correct': a photo of a

stream with a 1/800 second shutter would record each sharp sparkling droplet of water

frozen in mid-air, whereas a 4 second exposure would render the stream as a softly

flowing ethereal smoke. Either can look beautiful.
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A shutter speed of 1/800 second freezes this

baseball in mid-air.

A 10 second exposure produces streaked

lines of headlights and a ghost of a car that

was parked for half of the exposure.

Aperture, or 1, 1.4, 2, 2.8, 4, 5.6, 8Low f-numbers mean wide apertures letting in more light.

Aperture has a reputation for being complicated so some guides suggest that you just

memorize the f-number sequence and ignore the internal details. Being a geek, you'll

find it much simpler when you understand why it is measured like this.

A constant f-number means a constant amount of light entering the aperture

regardless of the focal length.

Each f-number is 1.4 times the previous one and lets in half as much light. Whensomeone says "close", "reduce" or "step down" the aperture, they mean increase the f-

number.

Like shutter speed, aperture affects the look of the photo, specifically the depth of

field. At narrow apertures the whole of a scene will be in focus, whereas at wide

apertures only the bit of the scene that you focus on will be on focus; as is clear in the

case of these cheap fake flowers:

At f/16 the background is distracting At f/1.4 the background is reduced to a blur,but not all of the subject is in focus either.

Long focal lengths and bokeh: Using a long focal length lens appears to make the

background more blurred. In fact the background is just as blurred, but is larger. This is

easier to see in a photo that only contains the out of focus background:
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A blurred leafy background at 30mm, f/2.8 The same shot at 85mm, f/2.8.

In both shots each leaf is just as blurred relative to its own size, but in the wide angle

there are more leaves and each one is smaller. In either shot you would reposition the

camera so that the subject filled the whole frame. The long focal length therefore

increases the size of the background relative to the subject, increasing the apparent blur.

This is useful in portraits, when background detail only serves to distract from your

subject.

Sensitivity

Historical aside

Film photographers had to choose a sensitivity when they loaded a new roll of film into

their camera, and some professional photographers carried two camera bodies loaded

with different film to give them a choice of sensitivity when shooting a scene. As adigital photographer you can change the sensitivity for each shot. Which is nice.

While we're on the subject of choosing film, many old school photographers loved a

film called Fuji Velvia which boosted the saturation in their photos. Digital SLRs

usually come with a saturation setting which allows you to emulate this. I shoot with

+50% saturation on my Canon 30D, which gives the same intense colour to scenes as

Fuji Velvia does.

The sensitivity of the camera's plate is measured in ISO sensitivity units which were

originally used to measure the sensitivity of chemical film. Most digital SLRs offer a

range from 100 to 1600, with 100 being the least sensitive. Some offer lower or higher

ISOs; as of September 2007 the champion is the 3,400 Nikon D3 with a maximum

ISO setting of 25,600.

Sensitivity is a very useful exposure setting, because it (almost) doesn't affect the look

of the final image, so can be used to help you achieve a combination of aperture and

shutter speed that gives you the look you need. Take this shot for example:


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The extreme depth of field required a narrow aperture of f/22, ensuring that the grass

and mountains were sharp, and my camera's meter decided that a shutter speed of 1/15

second was required to correctly expose the image. A breeze was causing the grass to

sway so much that a shutter speed of 1/60 was required to freeze it. 1/60 is 4 times

faster than 1/15, so the scene would be underexposed by 2 stops. I increased the

sensitivity by 2 stops from 100 to 400 and the scene was correctly exposed.

There is a caveat: noise. At very high sensitivities the picture becomes noisy. This is

because at higher ISOs you are making an image from a smaller amount of light, so the

signal to noise ratio drops. As a last resort you can try to remove this noise in

Photoshop, but this can also remove fine detail so it is better to get a clean photo in the

first place.

The following set of magnified images show individual pixels from a photo of a lamp

fitting at various ISOs. These results will hold true for most digital SLRs. However, top

of the line professional models will have lower noise at high ISOs.
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At ISO 100, no noise is visible At ISO 400 the picture is still excellent

At ISO 800, noise becomes visible At ISO 1600 the image is very noisy

However, noise is less obvious in print than it is on screen, so you may well be able to

get away with high sensitivities.

As a rule of thumb you should shoot in the lowest ISO that gives you the shutter

speed and depth of field that you need. If you need more depth of field but don't want

to reduce the shutter speed, increase the ISO and reduce the aperture. If you need a

faster shutter speed and don't want to lose depth of field by opening up the aperture,

increase the ISO and the shutter speed. If you're shooting a still landscape on a tripod at

ISO 800 and 1/100 second shutter speed, you're just wasting image quality: reduce the

ISO to 100 and the shutter speed to 1/12 second. Some SLRs and most Point and Shoot

cameras have an Auto ISO setting, which selects the lowest ISO that will give you a

reasonable shutter speed. What qualifies as "reasonable" is an exercise left to the

manufacturer, so you may still need to set the ISO manually if your camera's choice

isn't appropriate.


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I find that far more of my shots are ruined by motion blur caused by slow shutter speeds

than by noise so don't hesitate to crank up the sensitivity if you need to. In addition,

it is often possible to remove much of the noise on in processing. The following crop is

from a picture that had to be taken at my camera's highest sensitivity. The top half is

processed with the Photoshop pluginNoise Ninja.

Metering

Digital SLRs have built-in light meters that calculate the required exposure settings to

expose the object you're pointing the camera at as a medium tone. However, the camera

doesn't know what you're pointing at, and will happily expose a white subject as grey

unless you correct the exposure settings. You use the exposure dial to tell the camera

to render the object that you are pointing at as a lighter or darker tone.

There are 5 stops between black and white, so black is 2.5 stops below mid-toned and

white is 2.5 stops above mid-toned (take this as read for now, I cover it in more detail in

the next section). Strangely, my Canon 30D's exposure dial only covers 2 stops, so I

have to use manual mode if I need absolute whites or blacks.

The dial at the default

setting: the metered object

will be mid-toned.

The metered object will be

near-white.

The metered object will be

near-black.

You can set your camera to spot metering which meters a small area in the centre of

the scene, centre-weighted metering which meters the whole scene but pays more

attention to the middle, orevaluative metering which meters the whole scene.

Especially for evaluative metering, check the histogram (see the next section) right after

shooting to make sure that the exposure came out correctly.
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The metering lock button lets you meter a specific object, lock the exposure settings

for that meter reading, and then point the camera somewhere else to take the picture.

This is how you meter an object that is not right in the middle of your composition.

This waterfall looked white, so I

spot-metered it and dialed in 2 stops

of overexposure to make sure that it

looked like it appeared in real life.

You can also change the suggested

exposure values for creative effect. This

moody nebulous image was actually a

bright cloudy sky. I metered the cloud at thebottom, used the metering lock button to

record that reading, then dialed in 2 stops of

underexposure to render it near-black.

Digital SLRs have four useful exposure modes that work with metering. Program

mode chooses an aperture and shutter speed for you, leaving you free to think about

composition. Aperture priority mode lets you choose an aperture, and the camera will

set the shutter speed to correctly expose the scene; this is the most useful mode because

it makes it easy to get the best depth of field possible (set to minimum aperture) or the

fastest available shutter speed for the current lighting (set to maximum aperture).

Shutter priority mode lets you pick a shutter speed and the camera will set theaperture. In all of these automatic modes, you point the camera at an object and then

use the exposure dial to tell the camera how light or dark that object should be.

In manual mode the exposure dial works the other way round: you choose an aperture

and shutter speed, and the metering system will set the exposure dial to tell you how

light or dark the object you're pointing at is:

The exposure dial indicating that

with the current settings, themetered object will be 2/3 of a
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stop above mid-toned.

When I'm taking time to work a subject, carefully setting up shots with specific effects

in mind, I like to use manual mode since it forces me to think about the exposure

settings. When I'm walking around looking for interesting moments to take snap shots

of, I stick to the automatic modes.

Histograms

Digital SLRs come with a histogram display so that you can tell how an image is

exposed. Set your camera to show you an RGB histogram of each shot after you take it

so you can tell if it is correctly exposed and retake the shot if necessary. Later in this

guide I show you how to correct a poor exposure on a computer, but you'll get better

results and a smug feeling of competency if you get it right in the field.

Incorrectly exposed images produce histograms with large spikes at either end;correctly exposed images look like smooth bell curves. There is an example of each in

the next section.

Looking at the histogram after each shot is the fastest way to get a feel for correct

exposure.

Stops and exposure: advanced stuff

Recommended article:

Notes on the Resolution and Other Details of the Human Eye.

A fascinatingly geeky comparison of the dynamic range and other optical properties of

the human eye those of a camera.

Every device for capturing light has a dynamic range the number of stops between

the darkest black and the lightest white that can be captured. Shades outside this range

will be clipped, appearing featureless black or white. This is why, when somebody

shines a torch at you at night, you can't see their face the human eye can perceive 15

stops of dynamic range, and the torch bulb is more than 15 stops lighter than their face.

On a film camera there are 5 stops between the darkest black and the lightest white.

This is a much smaller dynamic range than the human eye can detect. This means that if

you have a scene with say a bright cloudy sky and a dark shaded valley, you can see

both in detail at the same time but a camera can not. If the shadows in the valley are

more than 5 stops darker than the white of the clouds, then either the clouds will be a

wash of overexposed white or the shadows will be a mass of underexposed black.

Digital SLR camera sensors actually capture much more information that just the 5

stops that you see on your screen. My Canon 30D captures 9 stops in total: 2 stops on

each side of the 5 stops you can see. It uses this information internally to adjust whitebalance, but in order to reproduce the rich, high-contrast look of traditional film the 9
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stops are clipped down to 5 to produce a JPEG file that looks like a traditional film

print.

Traditional film photographers got around the 5-stop limit by using graduated neutral

density filters attachments for the front of a lens that shaded the sky, decreasing its

brightness so that the sky and shadows could both be properly exposed. Don't bother:the digital artist has two tools not available to the film photographer that are far more

flexible. By using RAW image adjustment and combining multiple shots in

Photoshop, you can create your perfect exposure back in the office, leaving you free in

the field to focus on choices that can't be changed later like motion blur and depth of

field.

Software

Your camera may come with image editing software, but really you need something

more powerful. Personally I can't live without Photoshop; I hear good things about

other programs, but after 10 years of learning Photoshop I'm not interested.

Photoshop has had RAW import options since Photoshop CS released in 2003, but

Photoshop CS3 has by far the best RAW support to date. If you balk at the cost, save

50% by purchasing an old copy of Photoshop on Ebay, transferring the license to you

and upgrading. It saves you so much money that you almost feel it must be dodgy, but

it's perfectly legal. Make sure that it is a legally owned copy and that the seller is

willing to transfer the license to you.

If you still balk at the cost, try downloading The GIMP and then the RAW conversion

plugin UFRaw. Both are free.

Another useful bit of software isGenuine Fractals. Photos from an 8 megapixel camera

will print at A4 or even A3 size without modification. However, if you need to crop an

image to centre on a small area, you can find yourself with a much smaller image that

will become pixelated if you print it large. Genuine Fractals has a scaling algorithm that

detects hard edges and preserves them in the scaled-up version. The following crops are

from a picture resized in photoshop, and with Genuine Fractals:

Click for larger versions.
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RAW image adjustment

Digital cameras actually capture 9 stops of dynamic range and then clip it down to 5

stops when the image is converted to JPEG. However, if you set your camera to shoot

in RAW, all the clipped information will be saved so you can change your mind about

how you want it to be clipped later.

Here's an example of a tree that I shot against a bright sky on a sunny day:

The camera's automatic metering set the aperture to f/10 and shutter speed to 1/250

second which recorded the sky correctly as a light blue with bright white clouds.

However when I looked at the scene in person the tree was a brilliantly backlit bright

green, but here it is a dark silhouette around 2 stops too dark compared to how my

eyes saw it. This histogram of all individual red, green and blue pixel values shows the

problem clearly; the spike to the left is caused by all the detail darker than the lowest of

the 5 stops being clipped to plain black:

If I manually increased the exposure of the whole scene by 2 stops, say by decreasing

the shutter speed to 1/60, the sky would have lost all detail and become a wash of white.

The solution is to use a RAW adjustment program to selectively lighten the
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underexposed shadows without lightening the correctly exposed highlights. Your

camera should come with a program that does this, but if Canon's program is anything

to go by it won't be nearly as usable as Photoshop's RAW file import dialogue. Canon's

program is said to produce a higher image quality; personally I can't tell the difference.

Photoshop gives you a 'Fill light' slider that increases the brightness of the shadowsselectively:

And as you can see from the new histogram, the spike at the left is gone and replaced

with a nice smooth bell curve:

Of course there is a cost loss of contrast in the highlights, which had to be

compressed to make room for the shadow detail. Compare the second histogram to the

first. The three peaks for red green and blue to the right of the graph correspond the

gradient across the sky. They exist in both histograms, but in the second one they are

narrower: the difference between the lightest and darkest bit of sky is smaller than in

the first exposure, and hence the gradient across the sky is less dramatic. In this case,

the trade-off is easily worthwhile.

Combining multiple shots
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RAW image adjustment works well when you have no more than a couple of stops

underexposure or overexposure, because if you go more than 2 stops past the 5 stop

limit of a scene's dynamic range, you exceed the 9 stop dynamic range of your camera's

sensor and any detail in the poorly exposed areas is lost for ever.

Outside the window of my Norwegian holiday cabin where my wife is sunbathing it is abright day; inside where I am hunched over a laptop it is much darker:

In order to get a good exposure of

the inside, I needed a shutter speed

of 1/3 second at f/4

Exposing the outside correctly

required 1/80 second at the same

aperture

This 5 stop difference is far more than we can hope to recover with RAW image

adjustment. If you shoot both exposures, you can combine them in Photoshop using a

layer mask to create an image that would be impossible using a film camera:
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Using a mask used to

combine the 2 exposures ...

... in Photoshop ... ... Yields an image that looks

more like what my eyes saw

at the time.

I created the layer mask by inverting the dark image, blurring it, increasing the contrast

and retouching a few areas with the brush tool.

Make sure you shoot with a tripod so that the two exposures overlay accurately (unlike

in my hurried attempt, where blurring from hand-holding shows up in the interior shot

and rotating / resizing was necessary to realign the images). Then take both photos into

Photoshop as layers, add a layer mask, and use the brush tool on the layer mask to

literally paint detail into the shadows. It's surprising how well it works.

White balance

Artificial light is much warmer than sunlight, with more red and less blue in it. Your

eyes adjust to the current light temperature and after a while you won't notice it.

Cameras do not automatically adjust however:
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limitations of a small amount of kit produces better results than owning the 'dream bag'

of every lens you want.

Here are two ways of spending three grand:

Spend all 3000 on a 300mm f/2.8 IS lens: an object of beauty and arguably the finestlens Canon have ever made.

Spend 300 on a 70-300 f/4.5-5.6 IS zoom: not as glamorous, but very sharp, 1/10 the

price and only 2 stops slower. Spend the remainder on a 2 month-long holiday to an

exotic location taking pictures and learning how to use your equipment well.

Guess which one will yield better photos?

With this in mind, I recommend this path:

The body

First, choose Canon or Nikon. If you have friends who are into photography, choose the

same as them so you can swap lenses. If not then choose Canon because nobody ever

got fired for picking the market leader.

Buy a body with a high crop factor (see previous sidebar) because the body and the

lenses will be cheaper. If you're on a tight budget this means (as of late 2007) the Canon

350D / 400D or Nikon D40 / D40x. If you want to spend a bit more on a larger, sturdier

camera with big controls that you can use with gloves on - the image quality is

essentially the same - then go for a Canon 40D or Nikon D300.

The lenses

Buying the lenses is harder because there is so much choice, so start with the cheap kit

lens that comes with the camera and use it for a month or so until you notice its

limitations.

As you grow your kit, only ever buy a new lens when you have a specific kind of

photography that you can't do with your current lenses. Don't try and anticipate what

this might be, or you might end up with expensive lenses that you hardly use.

The most expensive lenses are ones with large apertures for shooting in low light.

Before you buy these, buy a good tripod and an off-camera flash unit (or two), and

learn how to use them.

My kit

I bought a Canon 30D with the standard kit lens.

I covered the focal length range that I use by buying another two middle of the range,

light-weight zooms:


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Sigma 10-20mm (220)

Canon EF 70-300mm f/4.5-5.6 IS DO (650)

Then for low-light photography I purchased a couple of wide-aperture prime lenses:

Sigma 30mm f/1.4 (250, and actually my big sister bought it for me, thanksFreddie)

Canon 85mm f/1.8 (225)

The latter is also an excellent portrait lens because of the wide aperture / long focal

length combination's effect on bokeh.

Finally I replaced the kit lens with a Canon EF-S 17-85mm f/4-5.6 IS (345), because

the kit lens produces some artifacts like chromatic aberration that were tedious to

remove in Photoshop.

Your mileage may vary: start with the kit lens and buy new ones only when you feel thelimitations of your current kit.

Filters

If you have multiple lenses, buy polarising and ND filters for the largest lens and then a

set of step-up rings to fit them onto your smaller lenses. You won't be able to attach

lens hoods, but this doesn't really matter if you're using a tripod since you can shade the

lens with a hand or a hat. If you must soot with filters anda lens hood then you have to

buy filters for each lens size.

Where to buy

I buy my kit from Ebay, which despite its reputation for dodgy sellers is quite safe if

you're careful. Use a specialist camera shop with high feedback and Paypal buyer

protection (a guarantee that if the item does not arrive, Paypal will arrange a refund up

to 500). If you buy anything that costs more than 500, test them with some purchases

under 500 first. Choose a seller from your country to avoid being stung by import

duties.

FiltersFilters were an important part of the prehistoric photographer's equipment. Coloured

filters could enhance a scene, warming or cooling it to compensate for different kinds of

lighting. Graduated neutral density filters decreased contrast within a scene, allowing a

bright sky and dark land to be captured in one exposure.

The digital artist doesn't need most of the filters because the effects can be applied

digitally white balance settings on your camera or in Photoshop affect the scene

warmth, and the advanced exposure techniques covered above are much more flexible

than graduated neutral density filters.
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There are a 2 filters that are very useful however, because they change the image in

ways that can't be reproduced by a computer:

Polarising filters

If you take any photos outdoors, you need one of these.

Light scattered through the upper atmosphere becomes polarised by ice particles, or

something like that, I forget the details. This polarisation survives being reflected off

shiny surfaces like sweaty foreheads. However, when light is absorbed and re-emitted

from a surface as coloured light, it loses its polarisation. Because of this a polarising

filter can do two things: remove white haze from the sky rendering it a deep blue, and

remove white reflections from surfaces revealing their true colour. Alternatively, if it is

the reflections you are trying to photograph, you can rotate the filter 90 degrees to

increase their brightness.

Photography on sunny days can sometimes be disappointing because the scene never

looks as colourful as it seemed to when you were there. Polarising filters help capture

bright scenes as they appear to the human eye.

A photo without a polarising filter. The

clouds are lost in a white sky that looked

blue to me when I took the photo.

The same shot with a polarising filter. The

sky is darkened so the clouds stand out

more. Now the only problem with the shot

is its utter lack of artistic merit.

Neutral Density filters

Neutral density (ND) filters are dark filters that reduce the brightness of a scene. You

may need them if you like to play with long exposures for artistic effect. Even at the

narrowest aperture, a 5 minute exposure will overexpose anything but the darkest night

scene. Adding a strong ND filter can allow you to use these extreme settings. An ND

filter can also allow you to take photos of very bright subjects without hurting your

eyes.
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An ND filter allowed me to get the 30

second exposure I needed to render this

babbling brook as a serene glassy flow.

Taking a photo directly into the sun would

have hurt my eyes without an ND filter.

ND filters are just another way of affecting exposure, so it should come as no surprise

by now that they're measured in stops. How strong a filter you need depends on your

requirements. I just metered a daylight scene at my camera's minimum sensitivity of

ISO 100 and minimum aperture of f/32 and was told that I needed a shutter speed of

1/50 to expose it properly. That is therefore the longest shutter speed I could achieve

without an ND filter. If I wanted to take a 5 second exposure, I would need an 8 stop

ND filter (1/50 doubled 8 times = 5). If I wanted to do a 5 minute exposure, I'd need a

14 stop filter.

Some filters are sold as, e.g. "8x" filters, which reduce brightness by a factor of eight.

This is equivalent to three halving of the brightness, so it is actually a 3 stop filter.

ND filters can be stacked together and their stop values add together.

Accessories

Tripod

You can hand-hold a photograph at a shutter speed of around 1/focal length, i.e. with

my Sigma 30mm lens on my 1.6x crop factor body, I must have a shutter speed of atleast 1/50 second to reliably hand hold it, and even then the occasional shot may have

noticeable blurring from camera shake. Buying an image stabilised lens (and they

aren't cheap) can let you hand-hold a photo at 2 or 3 stops slower than usual. For shots

that require slower shutter speeds, you'll require a tripod and a remote shutter release

button to avoid shaking the tripod as you press the shutter (though you can use the

camera's self timer for this).

Another benefit of a tripod is that it makes it easier to compose a shot. Especially in low

light and with telephoto lenses, framing and focusing a shot is hard. Using a tripod lets

you carefully set up the shot so that you don't accidentally clip off part of your scene or

introduce a wonky horizon.
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In fact, I'd go so far as to say that if you don't have a good tripod, you are wasting your

money buying expensive lenses. I have a Manfrotto 458(B) Neotec (215) and 468

MGRC2 head (165). This is expensive stuff, but it increases the proportion of my

usable shots far more than a new lens five times that price.

Macro dioptres

Macro dioptres are magnifying glasses that screw onto the filter thread at the end of a

lens and enable it to focus on very close objects. They are called dioptres because

Jessops wouldn't be able to charge 50 for a magnifying glass, but for a dioptre, now

that sounds like a bargain. Long zoom lenses typically have a minimum focusing

distance of 1 to 2 meters. With a Macro dioptre attached they can focus much closer,

enabling you to fill the whole photo with an insect for example.

When working with small subjects

close to the lens the depth of field is

very narrow - note how only the

petals at the front of the flower are in

focus.

An 'actual pixels' crop from the

image shows that it is extremely

sharp. I thought that you would need

a macro lens for this kind of quality.

I was wrong. Score 1 for my

philosophy of trying to get away with

cheap kit before getting expensive

stuff.

Make sure you buy a dual element dioptre, like those from Canon or Nikon. They are

optically far superior to the single element ones, and don't cost much more. A good

macro dioptre mounted on a sharp lens produces results just as good as a dedicated

macro lens, for a fraction of the price.

The end!
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I hope you've found this article entertaining. Think of it as the first section of a book:

now that we've covered the basics, we can have some fun. Every month (hopefully) I'll

publish a new chapter based around a certain technique. It might be long exposure,

flash, portrait photography or anything really. As always, I'll be writing from the

position of a beginner. If you have something you'd like me to write about, or any

questions or comments,post to my blog.

To subscribe to future photography articles, add this link to your RSS reader.

This work is licensed under a Creative Commons Attribution 2.0 UK: England & Wales

License.
http://www.berniecode.com/blog/2007/10/17/a-computer-geeks-guide-to-advanced-photographic-technique/http://www.berniecode.com/blog/2007/10/17/a-computer-geeks-guide-to-advanced-photographic-technique/http://www.berniecode.com/blog/category/photography/feed/http://creativecommons.org/licenses/by/2.0/uk/http://creativecommons.org/licenses/by/2.0/uk/http://creativecommons.org/licenses/by/2.0/uk/http://www.berniecode.com/blog/2007/10/17/a-computer-geeks-guide-to-advanced-photographic-technique/http://www.berniecode.com/blog/category/photography/feed/http://creativecommons.org/licenses/by/2.0/uk/http://creativecommons.org/licenses/by/2.0/uk/


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* The Point & Shoot alternative

Almost all professional photographers use SLR cameras, rather than point and shoot

cameras. SLRs offer very high image quality, a choice of lenses that affect the look of

the photo, and most importantly easy access to the exposure controls that are the subjectof this article.

However, top-of-the-range point and shoot cameras are very good these days. Some of

the photos in this article could have been shot with a P&S camera, others could not. If

you're willing to work within the limitations of a P&S camera, you can take beautiful

photographs.

The single most limiting aspect of P&S cameras in my opinion the depth of field. It is

very hard to get good background blur ("bokeh") with a point and shoot. If you search

on flickr for bokeh, you will see many beautiful photos with backgrounds blurred into

such simple washes of colour that they look like they might have been taken against a

studio backdrop. They were all taken with SLRs.

If you decide to get a P&S camera, seriously consider the Canon G9 for its RAW image

support (the importance of this is discussed later). As an absolute minimum, make sure

that the camera gives you access to the three important exposure modes: aperture

priority, shutter priority and full manual. Also, some P&S cameras have a "hot shoe" to

which you attach an external flash. This is indispensable if you want to take photos of

moving subjects at night, since on-camera flashes produce shockingly poor results.

Geeky aside camera body crop factors

The landscape shots above were taken with a Canon 30D digital SLR with an APS-C

image sensor about 22mm wide. Traditionally, lenses are designed for film cameras

with a 35mm film size, so the lens will project a 35mm wide image onto the back of the

digital camera. Because of the smaller sensor size, the camera body effectively crops

the image down to 0.625 of the width and height. Recall that cropping an image to 1/2

its size is exactly the same as multiplying the focal length by 2 (1/0.5 = 2), so croppingan image to 0.625 of its size is exactly the same as multiplying the focal length by 1.6

(1/0.625 = 1.6). This is why the 30D is said to be a '1.6x crop factor camera body'.

It is often said that these cameras multiply the focal length of a lens by 1.6. Now that

you understand focal length you know that they do nothing of the sort - the focal length

of the lens stays the same, but the smaller sensor size yields a narrower angle of view,

equivalent to a lens 1.6 times longer on a 35mm camera.

A smaller sensor may seem bad, and it's true that they offer less resolution than full size

sensor cameras like Canon's 5D, but they are popular with photographers who use

telephoto lenses a lot since they boost the effective length of their lenses for free, saving

them money and weight compared to buying a lens 1.6 times longer. With the growing
http://www.flickr.com/search/?q=bokehhttp://www.flickr.com/search/?q=bokehhttp://www.flickr.com/search/?q=bokehhttp://www.flickr.com/search/?q=bokeh


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popularity of APS-C camera bodies, lens manufacturers have begun to make lenses that

don't cast a full 35mm image on the camera, such as Canon's EF-S series or Sigma's DC

series. This means that they can be made smaller, lighter and cheaper for the same

image quality, the only downside being that they can't be used on cameras with full size

image sensors like Canon's 5D. You therefore save money twice: once because you can

buy shorter lenses, and again because you can use cheap EF-S and DG lenses.

For example, I shoot head portraits with a Canon's EF 85mm f/1.8. (210, 435g). If I

had a full size sensor camera then the equivalent lens is the EF 135mm f2.0 (500,

750g). One reader objected to this comparison pointing out that the 135mm is a better

lens, and he is absolutely right. However, photographers so good that the 85mm lens

limits the quality of their pictures are few and far between. If I ever become one of

these photographers, I shall buy a full-frame camera and the 135mm f/2L with the

advance ticket sales from my exhibition.

Historical aside

Film photographers had to choose a sensitivity when they loaded a new roll of film into

their camera, and some professional photographers carried two camera bodies loaded

with different film to give them a choice of sensitivity when shooting a scene. As a

digital photographer you can change the sensitivity for each shot. Which is nice.

While we're on the subject of choosing film, many old school photographers loved a

film called Fuji Velvia which boosted the saturation in their photos. Digital SLRsusually come with a saturation setting which allows you to emulate this. I shoot with

+50% saturation on my Canon 30D, which gives the same intense colour to scenes as

Fuji Velvia does.

Software

Your camera may come with image editing software, but really you need somethingmore powerful. Personally I can't live without Photoshop; I hear good things about

other programs, but after 10 years of learning Photoshop I'm not interested.

Photoshop has had RAW import options since Photoshop CS released in 2003, but

Photoshop CS3 has by far the best RAW support to date. If you balk at the cost, save

50% by purchasing an old copy of Photoshop on Ebay, transferring the license to you

and upgrading. It saves you so much money that you almost feel it must be dodgy, but

it's perfectly legal. Make sure that it is a legally owned copy and that the seller is

willing to transfer the license to you.

If you still balk at the cost, try downloading The GIMP and then the RAW conversion

plugin UFRaw. Both are free.
http://www.gimp.org/http://ufraw.sourceforge.net/http://www.gimp.org/http://ufraw.sourceforge.net/


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Another useful bit of software isGenuine Fractals. Photos from an 8 megapixel camera

will print at A4 or even A3 size without modification. However, if you need to crop an

image to centre on a small area, you can find yourself with a much smaller image that

will become pixelated if you print it large. Genuine Fractals has a scaling algorithm that

detects hard edges and preserves them in the scaled-up version. The following crops are

from a picture resized in photoshop, and with Genuine Fractals:

Click for larger versions.

Buying kit

This box used to contain a guide to choosing kit, but I deleted it: there are alreadyplenty of places on the net that will tell you how to spend your money (like the flickr

Canon andNikon groups, andphoto.net) and this page is not going to become another

one. Instead I want to share a philosophy for buying kit:

Firstly, there are people in the world who are taking better photos than you or I will

ever take, with worse gear than you or I will ever own.

Secondly, digital camera technology moves quickly: the cheapest digital SLR camera

you can buy today produces better images than the 5000 professional cameras of a few

years ago, and the point-and-shoot cameras of 5 years time will probably match the

SLRs of today.

Finally, while expensive gear is a pleasure to own, it will not improve the artistic value

of your photos. In fact, plenty of artists would agree that having to work within the

limitations of a small amount of kit produces better results than owning the 'dream bag'

of every lens you want.

Here are two ways of spending three grand:

Spend all 3000 on a 300mm f/2.8 IS lens: an object of beauty and arguably the finest

lens Canon have ever made.
http://www.ononesoftware.com/detail.php?prodLine_id=2http://www.ononesoftware.com/detail.php?prodLine_id=2http://www.flickr.com/groups/canondslr/discuss/http://www.flickr.com/groups/nikondslr/discuss/http://www.flickr.com/groups/nikondslr/discuss/http://photo.net/http://www.berniecode.com/writing/photography/beginners/images/interpolation-tree-fractal-large.jpghttp://www.berniecode.com/writing/photography/beginners/images/interpolation-tree-photoshop-large.jpghttp://www.ononesoftware.com/detail.php?prodLine_id=2http://www.flickr.com/groups/canondslr/discuss/http://www.flickr.com/groups/nikondslr/discuss/http://photo.net/


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Spend 300 on a 70-300 f/4.5-5.6 IS zoom: not as glamorous, but very sharp, 1/10 the

price and only 2 stops slower. Spend the remainder on a 2 month-long holiday to an

exotic location taking pictures and learning how to use your equipment well.

Guess which one will yield better photos?

With this in mind, I recommend this path:

The body

First, choose Canon or Nikon. If you have friends who are into photography, choose the

same as them so you can swap lenses. If not then choose Canon because nobody ever

got fired for picking the market leader.

Buy a body with a high crop factor (see previous sidebar) because the body and the

lenses will be cheaper. If you're on a tight budget this means (as of late 2007) the Canon

350D / 400D or Nikon D40 / D40x. If you want to spend a bit more on a larger, sturdier

camera with big controls that you can use with gloves on - the image quality is

essentially the same - then go for a Canon 40D or Nikon D300.

The lenses

Buying the lenses is harder because there is so much choice, so start with the cheap kit

lens that comes with the camera and use it for a month or so until you notice its

limitations.

As you grow your kit, only ever buy a new lens when you have a specific kind ofphotography that you can't do with your current lenses. Don't try and anticipate what

this might be, or you might end up with expensive lenses that you hardly use.

The most expensive lenses are ones with large apertures for shooting in low light.

Before you buy these, buy a good tripod and an off-camera flash unit (or two), and

learn how to use them.

My kit

I bought a Canon 30D with the standard kit lens.

I covered the focal length range that I use by buying another two middle of the range,

light-weight zooms:

Sigma 10-20mm (220)

Canon EF 70-300mm f/4.5-5.6 IS DO (650)

Then for low-light photography I purchased a couple of wide-aperture prime lenses:

Sigma 30mm f/1.4 (250, and actually my big sister bought it for me, thanks

Freddie)

Canon 85mm f/1.8 (225)


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The latter is also an excellent portrait lens because of the wide aperture / long focal

length combination's effect on bokeh.

Finally I replaced the kit lens with a Canon EF-S 17-85mm f/4-5.6 IS (345), because

the kit lens produces some artifacts like chromatic aberration that were tedious to

remove in Photoshop.

Your mileage may vary: start with the kit lens and buy new ones only when you feel the

limitations of your current kit.

Filters

If you have multiple lenses, buy polarising and ND filters for the largest lens and then a

set of step-up rings to fit them onto your smaller lenses. You won't be able to attach

lens hoods, but this doesn't really matter if you're using a tripod since you can shade the

lens with a hand or a hat. If you must soot with filters anda lens hood then you have to

buy filters for each lens size.

Where to buy

I buy my kit from Ebay, which despite its reputation for dodgy sellers is quite safe if

you're careful. Use a specialist camera shop with high feedback and Paypal buyer

protection (a guarantee that if the item does not arrive, Paypal will arrange a refund up

to 500). If you buy anything that costs more than 500, test them with some purchases

under 500 first. Choose a seller from your country to avoid being stung by import

duties.
http://en.wikipedia.org/wiki/Chromatic_aberrationhttp://en.wikipedia.org/wiki/Chromatic_aberration

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