Your camera - Astro and Night Sky Photography

Astro and Night Sky
Go to content

Your camera

Basics
Photography Basics
A little understanding of the basic fundamentals of photography will greatly assist you with low level light photography.
There are three basic elements or 'pillars' of photography.

1. Aperture
2. Shutter Speed
3. ISO

APERTURE
The opening of a lens through which light flows to enter the camera is known as the aperture.
If you think about how your eyes operate, it's a simple notion to grasp. The iris in your eyes get bigger or smaller when you move between bright and dark areas, affecting the size of your pupil.
So, aperture refers to your lens's "pupil" in photography.

It  allows more or less light to reach your camera sensor, you can reduce  or increase the aperture size, like squinting or opening your eyes  wider)
You could compare squinting your eyes to say f/11  and opening them wide as  f/1.8. (it also affects the depth of field)

This ' f ' number we referred to is the proportion of light you are letting to your sensor via the lens.
It is a little confusing but if you look at it exactly like a fraction it makes sense.




Example: 1/2  (half) a glass of milk is more than a 1/4 (quarter), a 1/4 is more than an 1/8 (eighth) of a glass.

Study the chart below.



    
f/2.8 is a large aperture (letting in large amount of light), f/22 is s small aperture (letting in a small amount of light)

So in the dark you would open your eyes wide open to see right?,  so open your camera aperture wide too! (f/2.8)


SHUTTER SPEED
Shutter  speed controls two things: adjusting the brightness of your photograph and creating dramatic effects by either freezing or blurring motion.
The  camera shutter – which is a curtain in front of the camera sensor that remains closed until you press the shutter button to take the photo.

The  shutter then opens and fully exposes the camera sensor to the light  that has passed through your lens when the camera fires. The shutter closes soon after the sensor has finished gathering light, preventing light from reaching the sensor.
Because  it opens and closes the shutter, the button that fires the camera is sometimes known as the "shutter" or "shutter button."
The  shutter speed of a camera is the time it takes for the shutter to open  and expose light to the sensor.It's basically how long it takes your  camera to take a photo. This has a few significant implications for the appearance of your photographs.

When  you utilise a long shutter speed (sometimes referred to as a "slow" shutter speed), you expose your sensor for a long time. The first major consequence is motion blur in moving objects and can give a sense of momentum such as vehicles, joggers and moving water.

Slow shutter speeds are also utilised with a tripod to shoot the Milky Way or other things at night or in weak light. This is because the slower  shutter speed allows more light to the sensor. Light being the stars on a  dark night.


Shutter Speed
Try this, take  a photo with a really fast shutter speed of a waterfall, or even a  sprinkler. Then take the same shot with a slower shutter speed.
Ensure you use a tripod.
Then at night, again with a tripod, do the same with your camera pointimg up at the night sky.
Compare your shots and you will have a better understanding of the effects of shutter speed.


ISO
In the very simplest form, ISO is a camera setting that lightens or darkens a photo. Your images will  get increasingly brighter as you increase the ISO setting. As a result, ISO can assist you in capturing photographs low-light situations or  allowing you to be more flexible with your aperture and shutter speed  settings.
Sounds great right? There are however some drawbacks in increasing your ISO.
A photo taken with a high ISO will have a lot of grain, also known as noise. Too much noise and it can ruin the image.

As  a result, increasing the ISO to brighten a photo is always a trade-off. Only increase the ISO if you can't brighten the photo with shutter  speed or aperture.
In  very low light -night sky photography we use a relatively high ISO compared to day time or flash photography. We need a little more light  to bring out the stars.
I have  shot with an ISO 10,000 which is extremely high and it has turned out okay.  Other times I have shot with an ISO of 64,000 and it has too much  noise/grain and is no good.
If  there is moonlight, keep your ISO somewhere between 1600- 3200. A very  dark night with no moonlight you may find you can increase it.

Photographs copyright L.Waite 2024
Back to content