Tripod-mounted unguided astrophotography is relatively easy to learn, and it doesn’t cost an arm and a leg. Here’s what you’ll need to get started:
· 35-mm SLR camera
· Camera tripod
· Guide Book
Choosing a Camera
Today’s modern, fully automated cameras make taking great vacation photos a breeze. However, many are not suitable for astrophotography. A basic 35-mm SLR camera with full manual operation is much better for this kind of work. There are several features you need. The camera should have a non-battery B (bulb) setting. This feature allows you to take long exposures without draining the camera battery. Some camera shutters require battery power to open and close. Some use battery power to hold the shutter open. A series of 15-minute astrophotos on a cold winter night will quickly drain the battery and leave the camera dead on the tripod. The non-battery B (bulb) setting is an essential feature of an astrophotography camera.
The camera should also have a feature called mirror lockup. A typical 35-mm camera uses an internal mirror to redirect light to the viewfinder. This allows you to see the image and set focus before taking an exposure. When the shutter is tripped, the mirror slaps up out of the light path. The image in the viewfinder goes dark because all the light is passing through the lens to the film. This mirror slap introduces a small amount of vibration. Since most daylight photos last a small fraction of a second, the vibration is not recorded. However, the longer exposures used to photograph the night sky will record any vibration caused by mirror slap. Images will look fuzzy and unfocused. Mirror lockup allows you to position the mirror out of the light path before the exposure is taken. This is another essential feature of a good astrophoto rig.
Also, look for a camera that accepts a variety of focusing screens. Most standard issue focusing screens work well for bright objects but do not allow you to achieve critical focus on the stars. A simple, clear, matte focusing screen is often the best choice. This feature is valuable but non-essential. Since all objects in the night sky are for all practical purposes infinitely far away, you can set the focus of your camera to infinity and get good results.
These are the main features that make for a good astrophotography rig. To summarize, you should look for a camera with the following:
· Non-battery B (bulb) setting
· Mirror Lockup
· Accepts a variety of focusing screens
Many newer cameras are so automated that they don’t make good astrophotography rigs. An older, used camera can be the perfect choice for the beginning astrophotographer. Here’s a list of older cameras that have all the desired features:
· Olympus OM-1 – The camera of choice for many
· Nikon F2
· Canon F-1
· Pentax K1000
With the exception of the Nikon, these aren’t necessarily top of the line cameras. However, they are affordable and offer the features you will need to take good astrophotos.
A camera tripod serves as a stable platform for the camera. Since astrophotos typically last several minutes or more, it’s not possible to hold the camera steady throughout the exposure. Bogen, Tiffen and Velbon are companies that make reasonably priced camera tripods. My favorite mail order company, Eagle Optics, carries these and other brands.
The tripod can be broken down into two areas, the legs and the head. The more expensive brands allow you to mix & match leg and head combinations. Valuable features to look for in a tripod leg include an adjustable center column, leg spread and telescoping legs. These features make the tripod easily adaptable to any terrain. Spreadable legs allow you to place the camera very low to the ground. Aluminum tripod legs cost more and are somewhat heavier than plastic legs. However, aluminum is stronger and more rugged while still being light weight.
The tripod head should allow pan and tilt motion in at least two axes. The better heads have motion through three axes, pan, tilt and side-to-side. This flexibility in motion is valuable to the astrophotographer because the constellations are oriented haphazardly across the sky. A two or three axis head is essential to framing the perfect shot. The head should have a safety lock that, when engaged, prevents accidental release of the adapter plate. You’ll be working with the tripod in dark and the last sound you want to hear is that of your new camera slamming into the rocky ground.
These are the features to look for in a camera tripod for astrophotography. Now, let’s take a look at astro film.
Wading through the ocean of photographic films to find the perfect choice for astrophotography may seem daunting. It really isn’t. The most important feature is speed. You want a fast film that will record a lot of stars in an exposure lasting a few minutes. The speed of a film is represented by an ISO number. The larger the number the faster the film.
The Moon is second only to the Sun in apparent brightness. Since it is illuminated by the Sun, you can use normal “daylight” speed films and exposures. ISO 100 and 200 films work well when shooting the Moon. The exposure times will be short, too. An exposure of 1/500-second will record the full Moon at f/4.5 on 200 speed film. Films ranging from ISO 400 to 800 are good for general photography of the constellations. Films as fast as ISO 1600 and 3200 work well for comets and other extended, faint objects.
Here’s the approach I use. First, I determine the film speed needed for the subject. Then, I go to the local discount retailer and buy whatever is on sale. Over time, I have come to like the Fujinon Superia color print film. You can go as high as ISO 800 and still get good sharpness. Faster films tend to look too grainy for my taste.
You may want to experiment with slide films. The advantage of slide film is that the processing can’t be botched. What you’ve shot is what will appear on the slide. Some photographers swear by slide films as the only way to go. Fujinon Provia is my slide film of choice. However, more often than not, I use color print film. Prints are easier to show off to friends and, should one of my photos miraculously turn out to be good, it’s easier to have copies made from print negatives than from slides. However, digital imaging technology and consumer scanners are quickly making this a non-issue.
The Guide Book
There is only one choice when selecting a beginning astrophotography guide book. Michael Covington’s Astrophotography for the Amateur is far and away the best guide book available. Covington skillfully leads you through the basics.
He guides the reader through the equipment choices and techniques using plain English. More advanced techniques such as prime focus guided photography are also covered.
The book is well-illustrated, and brimming with charts and indexes that allow the greenest beginner to chose the right exposure for a variety of subjects and setups. In short, the best thing you could do at this point is go to Amazon.com and buy his book.