Hi. Chris Hadfield here on the International Space Station inside the cupola.
I hope people are enjoying all the pictures we've been taking.
It's not Instagram, it's Space-a-gram.
Let me show you how we take these pictures.
We orbit 400 kilometres above the Earth.
So if you want to get a good detailed picture of something, you need a long lens.
I have one velcro-ed to the wall.
This is the big one, 400mm of many pieces of glass so we can focus on what's going on in the world.
Three important things when you take a picture from space: focus, frame and fire.
Let's talk about camera settings.
Typically the light from the Earth is very bright and of course, space is very black.
The camera gets confused if you mix the two.
So often, we'll set it to manual.
So if you can see over my shoulder,
the camera is on, I'm going to set my mode to manual and then we use the sunny 16 rule.
So I set my F-stop to about 16.
So I've got manual 16.
You can choose your ISO based on just how bright it is,
but typically about 200 works fine with the Sunny 16 rule and we use very high resolution pictures.
So we set it in the back here, we use an F format, not jpeg.
So each pictures is about 10 megs.
It rapidly fills up the card, but that's how we set our camera to take a picture in space.
One of the most striking parts of the world is the Sahara, a huge barren colourful rock, no vegetation covering it up.
You can see all the textures and varying shades of the world.
The Sahara is beautiful, we're coming up on it now.
This beautiful cloud is just on the coast, the brown and blue of Africa.
It's just around lunchtime on the Sahara right now, so the sun is coming straight down.
It makes for a nice time to take pictures because the light is very strong on the surface, so it's good to get the detail.
Something I really look for are edges and borders and changes
and the Sahara has those where you go from one ancient style of rock to another or where the dunes of the desert are -
have stopped in one area and started in another. So they almost make straight lines and weird textures.
It looks skin or hide and I often look for those in space.
We're going around the world 8 kilometres a second.
The sun and the Earth are sort of in a fixed geometry,
but we're moving so the angle between us and the sun and the Earth is changing,
and therefore, the reflection of the sunlight changes.
So we get a sun glint off the surface and you can see water on the surface so nicely in the sun glint
and pick out rivers and lakes and ponds.
You can follow a whole river as the sun glints along it,
something that you could barely see normally.
When you catch the sun's glint and it glows like a silver worm or a vein of ore and then the angle changes
and it - it's as if someone turned the lights off in the river and it wakes up.
The beauty of space station is if it's not here at this time, tomorrow it might be,
or maybe next week or maybe a month from now,
but there's not a race to get a picture.
You can be patient like a hunter.