Photography Basics
I wrote this for a guy in the office who had just bought his 1st SLR (D or otherwise) – a Nikon D50. It may be of help to others too.
To begin with, don’t get bogged down in too many techniques & technicalities. Photography is about capturing images – it’s not an engineering or physics Master Class or University Degree course. I’d argue the following are what you need to know.
The Basics
Aperture/F stop & Shutter speeds :
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Unless you are using flash - use Aperture Priority (Av), & start from f8 for landscape or f4 for people.
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F or f = Aperture, or the size of the hole (created by the lens diaphragm) that lets light pass thro’ it & enter onto the sensor.
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Strangely, f2.8 is a LARGE aperture, & f16 is SMALL.
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F2.8 is LARGE because it is a bigger hole (O) than f16 ( o ), which is SMALL by comparison.
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LARGE is also known as WIDE (but not WIDE angle, just WIDE open), or FAST (because the bigger the hole - i.e. the nearer to 1 that F or f is – the more light gets in, so the faster the shutter speed can be if exposure remains constant).
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Full F stops are 2, 2.8, 4, 5.6, 8, 11, 16, 22. Each step is a halving (or doubling) of the amount of light (so long as the shutter speed remains constant).
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Full stop differences in shutter speeds are halving (or doubling) of the speed – i.e. 1/1,000 (of a second), 1/500, 1/250, 1.125, 1/60, 1/30, 1/15…
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In an equation where overall “exposure” remains constant, as the Aperture (F or f) gets smaller (the higher the numeric value), the slower (longer) the shutter speed becomes - & vice versa.
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So 1/125 @ f8 is the same as 1/250 @ f5.6 (double one means ½ the other – or vice versa), or 1/60 @ f16, or 1/1000 @ f2.8. The outcome is that the quantity of light reaching the sensor is always constant, no matter what the shutter-speed/aperture combination are - see table 1.
TABLE 1
Shutter Speed (of a second) |
1/15 |
1/30 |
1/60 |
1/125 |
1/250 |
1/500 |
1/1,000 |
Aperture F or f |
22 |
16 |
11 |
8 |
5.6 |
4 |
2.8 |
Depth of Field |
Very Deep |
Very Deep |
Deeper |
Deep |
Shallow |
Shallower |
Very Shallow |
Blur/Motion Effect |
Some |
Some |
So, so |
Little |
Very Little |
None |
None |
Aperture/F stop & Depth of Field (DoF) :
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The smaller the hole (the higher the numeric F or f value), the larger/deeper the depth of field – i.e. the range of distance in focus from front to back. This is typically used for landscapes where you want maximum detail & visual information, from the flowers in front of you to the mountains in the distance. F8 or smaller (i.e. f11 or f16), is standard practice. Use whatever suits you at f8 or more, but remember that the smaller the hole the longer the shutter speeds, & in some instance this will allow water, clouds, cars – any movement – to blur. Typically this will begin happen at 1/30 second or longer. 1 second will totally blur water, & sometimes clouds will not be sharp either. See below left for large DoF & below right for long shutter speed (20 seconds) blur.
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Use 1/90 or 1/60 of a second for taking pictures of helicopters in order to show a little (natural) movement in the rotors. -
It is very difficult to get sharp, detailed shots at slower than 1/60 (some argue 1/30) of a second, hand held (without a tripod, or other means of solid support).
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The larger the hole (the nearer to 1 the numeric F value), the smaller/shallower the depth of field – i.e. the range of distance in focus from front to back. This is typically used for portraits to make the background out of focus & thereby concentrate the viewer’s attention on what is in focus – the face. Typical f values are f5.6 or wider (i.e. f2.8 or f4). See at left for an out of focus backdrop - you cannot tell what is in the background at all.
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The closer to the camera (the nearer the point of focus to you/the lens), the lesser the depth of field (DoF) at any given exposure combination.
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The hyper-focal theory says that to gain maximum DoF you should focus on a point 1/3 of the way into the DoF you require. So if you are at point A & want your image to have a DoF from point B to point C, you should focus 1/3 of the way from point B to point C. If your camera has a DOF preview (usually a button next to the lens mount) use this (but the D50 doesn’t have one). The viewfinder will darken but a visible difference should be available.
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The above is illustrated further in the diagrams below - first a large DoF, then a shallow DoF :
Basic Guidelines :
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Set - & keep – the colour space to Adobe RGB (RGB 1998 or Adobe 1998 RGB). But not sRGB.
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Set white balance to Auto.
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Accepted rule for hand holding a camera & the shutter speed to avoid shake is the focal length of the lens inverted to the shutter speed x1.5. So if you have a 100mm lens, the shutter speed should be 1/150 or faster (i.e. 1/250) to avoid shake.
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If you are using slow shutter speeds/small apertures (for landscapes) &/or long/heavy lenses (300mm or more), get - & use – a decent tripod with a solid head/quick release system (the Arca Swiss dovetail system is the industry standard).
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Always take a moment to compose the photo through the viewfinder. Check for distractions or things you’d rather not see – someone’s head, hand, foot, the branch of a tree, TV aerials or power-lines in landscape shots etc. Also check for things you want to see – are someone’s feet, or arm or ear missing ? Check the extremities for both. I often wish I had a set of step ladders that I could climb up to get above the heads, arms, hats, bushes, road signs, hand rails...
Exposure Meter Settings
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My advice is to experiment with your camera using each of the different camera settings available in a variety of different conditions/situations – i.e. indoors, portraits, outside in bright sunlight, outside in overcast, cloudy &/or stormy conditions, night time, portraits, on the beach or in snow. Find out which works best – both in general & for any given circumstance - & stick with it.
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For the majority of the time I use Centre Weighted Average on the 1D MkII, simply because that’s what I find works consistently. Occasionally I’ll use Spot Metering if there it high contrast & I want to emphasis a certain subject/area. Spot works by calculating the exposure of a small area – usually 5% or less of the viewfinder - & is often set to the centre point, but can usually also be linked to the AF sensor(s).
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Although you can regain a lot of shadow - & some highlight – detail in Photoshop, it is far better to have the image correctly exposed from the start.
Exposure Compensation & Exposure Bracketing
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These are basically similar, & they do the same thing, only the execution is different.
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The aim of both is to adjust the quantity of light reaching the sensor, thereby either making the image darker (under exposed) by causing less light to enter, or making the image brighter (over exposed) by allowing more light to reach the sensor.
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Exposure compensation does this by you dialing in a given amount more, or less, & the camera then takes the shot at the settings it is told – i.e. exposure plus one stop (the equivalent of 1/60 @ f8 on Table 1).
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Exposure bracketing – surprisingly – “brackets”. This means it does a photo on either side of the “normal”. So if you “dial in” +/- 1 stop, it will take one photo at the metered setting (i.e. 1/125 @ f8), one at one stop “less” (underexposed – i.e. 1/250 @ f8) & one at one stop more (overexposed – i.e. 1/60 @ f8). Note, in Av mode (Aperture priority), the aperture (f number) will remain constant & the shutter speed will change to accommodate the +/-. In Tv (Shutter priority), the shutter speed will stay constant & the aperture (f number) will change. -
At right is an image shot using Exposure compensation. Here, “underexposure” was dialed in to make the image darker. This had the dual effect of making the foreground virtually black (i.e. a silhouette) and also saturating the blue sky (slight underexposure - i.e. 1/3 of a stop - often makes blue more blue).
