So I just found my DSLR Camera – Nikon D3100 to be precise; tucked away in a box as I put it there years ago after buying it to teach myself photography.
Thinking back to the purchase, I can’t figure out why I spent a couple hundred on the camera but here I am.
Can anyone summarise the different things such as aperture, shutter speed, white balance, and anything else I haven’t listed?
Hopefully this will help other purchase happy shutterbugs with the basics.
In: Technology
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so the 3 important parameters are
*shutter speed*
the speed at which the shutter opens and closes to expose the sensor to light. a slower shutter speed = a longer exposure time = more light = brighter image. the slowest i tend to shoot handheld is 1/20th a second at a push. any slower and the shakes from my hand show up in the image.
You can capture some lovely timelapse effects with a slow shutter speed, or freeze the motion of eg: a dog using a fast shutter speed.
*Aperture*
The amount the aperture of the lense will shrink to. This is kind of a confusing one, but basically the lenses have a set of blades arranged so they form a ring that can be adjusted in size. lower aperture = the ring gets bigger. Dropping the aperture means that the ring is bigger, allowing more light to the sensor, brightening the image. it also has the benefit of adding visually pleasing ‘bokeh’ to the image at low apertures. conversely, increasing the aperture, also called the f number, means less light can get in, darkening the image, reducing bokeh, and increasing the ‘depth of field’. DoF is basically the distance around your focal point that is also in focus.
Imagine you focus on someone 2m away with a 50mm lens, with your lens set to f.2.
At this point, if you didn’t refocus, and the person stepped forwards or backwards about 15cm, they’d be blurry. if you did the same at f.20, they’d still be mostly focussed.
*focal length*
The focal length adjusts how the light is reshaped when it goes into the lens. lower focal lengths mean the image is ‘wider’ and more stuff is shown in the image. higher focal lengths zoom in on specific objects.
as an example, most people reccomend a 50mm lens for your first lens, but most cameras come with an 18-55mm lens. our eyes see somewhere between 35 and 50mm equivalent, so these allow for natural looking compositions. if you want to do landscapes, you might want a high quality ~15mm, and for wildlife, a ~500 which is basically a telescope. some lenses zoom, and non-zooming (prime) lenses tend to be cheaper, or have a lower minimum aperture.
*iso*
This is basically a digital increase in brightness done after the image has been taken.
Say you’re trying to take a photo at dusk, and despite your best efforts, you can’t get the image correctly exposed at the lowest aperture, and with the slowest shutter you can hand shoot.
Your options are pretty limited. you can get a tripod, but if your subject is moving, this won’t help much. the next option is to increase ISO. This effectively multiplies all the light your sensor sees. at ISO 400 your image is 4 times as bright as at ISO 100.
A side effect of bumping up the ISO is that any noise in the image also gets amplified. For that reason, it’s best to keep your ISO low unless you need more light. In the daytime, i try to shoot at ISO 100. how much ISO you can get away with depends on your camera. mine gets very noisy at 3200, so i never go over 1600. Its also possible to shoot raw at ISO 100, and let your images be underexposed, then try to fix them in lightroom. whilst this works, you won’t be able to see the image on-location, so it’s difficult to make work.
With those settings in mind, take your SLR, set to manual, and look through the viewfinder. there’s a little bar along the bottom edge. It’s telling you if the image is correctly exposed. If the blob is to the left, you’re underexposed (not enough light), and to the right is overexposed. try balancing your shutter, aperture, and ISO to keep the blob on or just to the left of the centre (some underexposure is ok in most images and can be fixed afterwards if needed).
When i got my first DSLR I spent the first week or two taking mediocre pictures, but practising using the dials to correctly expose the image, and then being able to weight the settings towards say, a fast shutter, or a low aperture etc.. Bring the camera into lots of different conditions and practise getting your exposure correct. after that you can let your artistic side reign free and find interesting scenes whilst knowing you can correctly expose the image.
Here’s my flickr 🙂 https://www.flickr.com/photos/148065716@N06/
How bright your image becomes is determined by the combination of aperture, shutter speed, and ISO. With shutter speed and ISO, the image becomes brighter the higher the value. With aperture it’s the other way round.
## Exposure (triangle)
The following can be summed up by this handy graphic:
https://i.imgur.com/2vfPgU3_d.jpg
### Shutter Speed
Shutter speed is the speed in seconds—or fractions thereof—of *exposure*. This is how long your sensor will “see” your image subject. By increasing the shutter speed, your image gets brighter but you also risk blurring. Either due to objects moving or due to camera shake if you do not use a tripod.
### ISO
ISO—in its simplest explanation—could be summed up as “sensitivity”. The higher the value, the brighter the image. With the downside of introducing significant ”noise” (comparable to film grain) for higher (>1600, but depends on the camera) values.
### Aperture
Aperture—the f number—determines how “open” your lens is. How high the largest aperture (lowest number) is, is different for each lens. If it is wide open, you get a brighter image compared to it being closed down. What actually happens when closing down is that the aperture blades form a smaller circle(-ish) opening light passes through when exposing.
You could always shoot wide open for the brightest possible image for your lens. However, the wider open the aperture is, the less sharpness and “depth of field” you get. This is because of the size of the hole that lets the light in. By not focussing the light through a smaller hole and instead having a larger hole, the parts you didn’t focus on get blurrier.
#### Depth of field
Depth of field is the depth in three-dimensional space of the perceived sharpness. If you focus on a person and have a low aperture number (i.e. wider opened lens) the person will probably be sharp while the background and foreground won’t be.
Depth of field is not always the same, even when using the same lens and aperture setting. It depends on a combination of the following:
– Sensor size (35mm, APS-C, Micro-Four/Thirds, …)
– Subject distance
– Focal length (the number in your lens. For example 50mm for a 50mm Prime lens or anything between 18 to 55mm on a 18-55mm zoom lens)
– Aperture (lower value: Smaller DoF; karger value: higher DoF)
Here is a screenshot of the app PhotoPills and its depth-of-field calculator. You can see here that for a 50mm lens set to f/4 aperture on your camera, standing 3m away from your subject, you would get a depth of field—i.e. area that is reasonably sharp—of 0.55m. Starting at 0.2m in front of and 0.35m to the back of your subject.
## White balance
White balance determines how yellow-ish or blue-ish your image becomes. The goal for good reproduction of colour is to get the tone of, for example, white or grey within the image as close to how you perceived it.
The white balance setting is measured in Kelvin—a measure for temperature—, which is why it’s also often called colour temperature.
Lower temperature values—e.g. 4500K—result in a more blue image, while higher values—for example 7500K—result in a more yellow image.
Which temperature you choose depends on your surroundings. As a rule of thumb, you could try 5500K for a sunny day with almost clear sky, 6500K for shade, 7500K for a grey, overcast day.
If you don’t want to trust the automatic white balance metering of your camera, you should shoot images in RAW format instead of JPEG. This way, you can change the colour value to your heart’s content later on, with the slight downside that you get larger files, and have to edit each image before being able to post it somewhere.
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