Film Astrophotography Techniques

DISCLAIMER: As this site is entitled, I am teaching the hobby of astrophotography with a FILM camera only. Digital photography is growing in leaps and bounds and offers some advantages over film, but also some disadvantages and the quality of film imaging can not be underestimated. While much of the material on this web site is beneficial to the digital photographer, the focus is on film imaging only. If you wish to capture the universe with a digital camera there are plenty of web sites to help you.
Astrophotography Introduction

To capture the beauty of the universe, you have to understand the major problems with doing so. Unlike conventional photography, there are some very unique obstacles to overcome:

  • Objects are moving. Well, the object you are photographing is NOT so much moving - as YOU are. As the Earth revolves, the sky appears to rotate once per day above us. This means every thing you photograph in the sky is a moving target, and thus can be blurred easily. You will need to pan your camera at a very precise rate to track them perfectly. Even though you can not see this movement with your eyes, your camera will within a few seconds. As you move up to photographing through a telescope, you must track the moving objects very well, and being off by as little of 1/4 of second will ruin the shot.
  • Dim Objects. Most of the objects we are going to photograph are extremely faint, some are actually invisible to the naked eye. This means you have to take long time exposures to collect the faint light and create an image on film. It also means it will be difficult to find, and focus your camera on these objects. Many beginners think astronomy subjects are very tiny. This is not usually the case, they are just too faint to see. As seen from Earth, many splendid objects in the Cosmos are several times larger than the full Moon!
  • Film is not sensitive. This last problem is simply that many of the wonders of the universe shine in a specific light frequency that ordinary film may not record. It's not that they are invisible, it's just that film companies are not expecting their customers to be taking such photos, so they manufacture their films to cover conventional objects in daylight. However, there are a few films that are very sensitive to these faint colors, and we'll have to stick with those to achieve the best results.

All the above problems, and a few others will have to be overcome to achieve our goal. The rest of this web site is devoted to helping you achieve that goal. The one mistake that beginners always make is to ignore the basic techniques and rules I will describe. THERE ARE NO SHORTCUTS will be a phrase you will hear me say time and again. Astrophotography is a demanding, precise skill, as much as an art form. The results are images of pure beauty unseen by most people. Enjoy!

Film astrophotography - North American NebulaIn order to capture the colors and beauty of the cosmos, you will need at the very minimum a camera capable of taking time exposures and a tripod or other stable platform to hold the camera. That's it. As we strive to capture smaller or fainter objects we will advance to using telephoto lenses, telescope, motor driven mounts, and become intimately familiar with our universe. The photo on the left was taken with an ordinary 35mm camera and a simple 135mm telephoto lens. If you are new to this hobby you will need a basic understanding of astronomy. This web site is not a lesson in this science, so you will have to gain that knowledge elsewhere. Check the LINKS section for a listing of excellent web sites that will help you. As a minimum you should have a basic understanding of the seasons, constellations, sky coordinates, the solar system, galaxies, nebula and the Milky Way. You should also have an understanding of how a 35mm Single Lens Reflex (SLR) works. Once you have this knowledge you will have little trouble understanding the technique and skills of astrophotography.
Before we continue, it is important to understand what kind of images we are trying to capture.
There are basically 2 types: Fixed Mount and Tracked mount images.

film astrophotography - star trailsFixed Mount images (constellations, star trails, aurora etc...). These are photos on mounts that do not move. Long exposures will show the Earths rotation as stars will blur (trail) from this movement.

What happens if you do NOT track? What you will see is that the object you are photographing will blur or TRAIL as the earth moves your camera. The best photograph to illustrate this is called a STAR TRAIL photograph. In this example, you mount the camera on a tripod and then point it anywhere in the sky and hold the shutter open for several minutes or more. The longer you expose, the longer the stars will trail. If you point the camera at the CELESTIAL POLE all the stars will appear to rotate around that point, creating beautiful arcs across the sky. This is an exciting first picture, as it shows the skies motion, or more accurately, YOUR motion under the sky. The photo on the left is a beautiful star-trail photograph taken in the southern hemisphere by amateur astronomer Ray Palmer. Notice how the trees and house are NOT blurred, while the entire sky revolves around one point. If Ray was to walk towards that point he would end up in Antarctica at the South pole! Astrophotographers in the Northern hemisphere see a similar sight, as the stars rotate under the North Star, Polaris.

I'll give lots more details of how to capture images like this in the TECHNIQUES section of this tutorial.

Tracked photography: This is the bread and butter of astrophotography. It enables very long exposures, lasting over an hour in some cases, with no ill effects from the camera's (Earth's) rotation. Almost all astrophotography, from amateurs to the Hubble Space Telescope, use some form of tracking. The majority of this web site is devoted tracked photography.

To begin tracked astrophotography you must solve two problems:

The Earth rotates at a constant rate, too slow for you to move by hand without introducing some shake, which will ruin exposures with much magnification. The Barn Door mount descibed under MOUNTS, will show you how you can track by hand, but only for short periods and opnly with a short camera lens. If you are photographing through a telescope, you MUST have a motor system to track the sky.

The second problem is that the Earth is at an angle, so the sky moves in one long contiunuous arc. Look at the star trail photo above. The whole sky is rotating around one point, and you will have to rotate your camera likewise. Fortunately there are some clever ways to do this and they will be discussed in the MOUNTS section.