What is Astro Photography?

Astrophotography is a specialized type of photography that involves making photographs of astronomical objects in the night sky (such as stars, planets, deep sky objects, star clusters, and galaxies).

It is used to reveal objects that are too faint to the naked eye.

Astrophotography poses challenges that are distinct from other genres of photography.

Astrophotography Using Digital Camera

DSLR or Mirrorless

A wide-angle lens

Battery Grip

Additional Batteries & Memory Cards

Shutter Release

Tripod is MUST!

Session Planning: Planning what to shoot?

Step 1 – Calculate the Moon Phase

Dark skies are essential for star photography.

Even a small crescent moon provides enough light to reduce the brightness of the stars, as seen by your camera.

This means you want to shoot when there isn’t a moon in the sky.

During the New Moon Phase, the moon can not be seen in the sky.

In most cases, 5 days before and after the New Moon are the best times to shoot.

This will change slightly depending on where you live on earth and the time of year.

Step 2 – Find Dark Skies without Light Pollution

Photopills app, dark site finder is great for finding areas without light pollution.

Black areas on the map are great for shooting the night sky, while white areas on the map are light-polluted and should be avoided.

Step 3 – Find Clear Skies & Predict the Weather

You don’t need perfectly clear skies to get great images of the stars and night sky.

I actually prefer to have some clouds in the sky because they add to the composition and “interestingness” of the scene.

Aiming for nights with 0-50% cloud cover will yield the best results.

Step 4 – Determine Moonrise & Moonset Times

Generally, 1-2 hours after sunset or moonset the skies are dark enough for star photography. This darkness will start to fade 1-2 hours before moonrise or sunrise.

Step 5 – Learn to Use Google Earth / Maps

Google Earth is a great way to see where the Milky Way is in the sky.

It’s also one of the best ways to visualize the topographical layout of a location prior to arriving.

What is the 500 Rule?

THE 500 RULE is a simple formula to calculate proper exposure time/shutter speed with a particular lens, full-frame, and or crop sensor camera. This formula, if done correctly will produce those pin-point, razor-sharp stars without any trailing in your Milky Way photos or images of the night sky.

HOW TO USE THE 500 RULE

It's fairly a very easy thing to remember and pull off. You take the number 500 and then divided it by the focal length of your lens = the longest exposure before stars start to trail or blur. For example; let's say you're taking a shot with a 16mm lens on a full-frame camera. 500 / 16 = 31.25 seconds, which you can round to 30 seconds. I'll always run down to the nearest zero.

(NOTE WHEN USING A CROP SENSOR CAMERA YOU HAVE TO MULTIPLY THE CROP FACTOR FIRST BY THE FOCAL LENGTH OF THE LENS BEFORE DIVIDING THAT NUMBER BY 500.) 

CAMERA CROP FACTORS

Sony & Nikon = 1.5 crop factor (EXAMPLE) 1.5 X 16 = 24 | 500/24 = 20 SECONDS

Canon = 1.6 crop factor (EXAMPLE) 1.6 x 16 = 25 | 500/25 = 20 SECONDS

A CALCULATION CHART FOR POPULAR FOCAL LENGTHS FOR FULL FRAME CAMERAS

(all calculations was rounded down to the nearest zero)

12MM = 41 SECONDS

14MM = 35 SECONDS

16MM = 30 SECONDS

20MM = 25 SECONDS

24MM = 20 SECONDS

28MM = 17 SECONDS

35MM = 14 SECONDS

50MM = 10 SECONDS

What Is The NPF Rule And How To Use It For Star Photography?

When you look at the stars in the night sky, you see them as sharp pinpoint lights and so when you photograph them, you will want to record them as sharp points. Due to the rotation of the earth, the stars seem to move across the night sky (although the stars have their own movement around the center of the galaxy) and during very long exposures, we see those star trails recorded in our images.

Why Sharp Stars?

Photographing star trails is a completely different thing and is done by choice, but when you want to photograph sharp point stars or even the Milky Way, you need to expose your camera’s sensor for the correct period of time, so even when you zoom in to the image or print them large, you will not be able to notice any trails in there.

Sharp Stars Require:

Perfect focus

Perfect exposure

How Do You Get Sharp Stars?

In order to achieve this, you will need to calculate the correct exposure time based on the type of camera (full-frame or APS-C or micro four thirds, etc.), lens combination, and use that value as your shutter speed in order to avoid star trails.

The NPF Rule

A more complex formula for calculating shutter speed at night is called the NPF rule.

Here’s the formula: 35 x aperture + 30 x pixel pitch÷ focal length = shutter speed in seconds.

(Pixel pitch is the camera sensor’s physical width in millimeters ÷ number of pixels in width x 1000 to measure it in microns.)

T = Recommended shutter speed

K = Multiplication factor

N = F-number

F = Lens focal length (millimeters)

P = Pixel pitch (micrometers)

δ = Minimum declination