Astrophotography, Part 2
by adminOK, in our last entry, we discussed the basics of astrophorography and its difficulties. In part 2 we will discuss what things can be photographed with your telescope and camera.
Let’s start with the stuff that needs minimal equipment and work our way up:
STAR TRAILS. Star trail shots are when you aim a camera at the night sky without any telescope mount (just a standard camera tripod) and open the camera shutter while the stars move through the night sky. This can make for some very pretty images. All that is needed is a manual setting on a SLR camera and dark, moonless night skies (if you don’t have dark skies the shot will get washed out). Set the camera for a 10 minute or longer exposure time (the longer the shot the longer the trail, but the greater chance of something happening to the camera).
The Moon. Our nearest satellite is so bright that almost any telescope that can couple a camera will work, even altazimuth mounts or Dobsonian telescopes can do it! Exposure times need not be long, in fact a common trick of old was to put a hat over the aperture of the telescope, open the shutter of the camera, and then ‘flip’ the hat on and off the telescope tube! This is a bit of a dated method as telescopes have gotten larger and very few folks own a hat that can cover a 10″ reflector tube. But the technique can be modified to work with a larger telescope using some other cover besides a hat.
Star Fields: Here, you are not using the telescope’s optics, but rather the equitorial drive and mount. You can either just put the camera on the mount, or you can ‘piggy back’ the camera to the telescope tube as many larger telescopes have an adapter to mount a camera. If you use the piggy-back method then you can use the telescope as a guidescope. Set the camera to its fastest film setting, and then take a shot that is 10 minutes or longer. If you do it right, you can get impressive shots of star fields. If you point at an area that has a bright Deep Sky Object, such as Orion, you can get even get a decent picture of that object in the star field picture. Star Field shooting is the best technique for beginning Astrophotographers as it gives them experience of the ‘feel’ of astrophotography without any special equipment.
Planets: Its not hard to to photos of the planets, but it is hard to take good shots of the planets. Many fuzzy shots of Saturn or Jupiter have been taken over the years. But the best shots of planets are taken with long focal length telescopes (1200mm f.l. minimum), perfectly collimated, with a long f.l. lens. The exposure time does not need to be long (2-15 seconds), but the system needs to be tracking almost perfectly, and be almost perfectly collimated.
Nebulas & Galaxies: Large aperture telescope is needed, but usually with a short focal length. Exposures depend on how bright the nebula or galaxy is, but shot time runs from 10 minutes and up. Use the camera’s fastest film setting. The Direct Objective method is probably the best way to take these kinds of shots and a guidescope is almost a requirement.
There are other objects in the night sky that can be shot:Star Clusters, Comets, and even the sun. But these object guides will give you an idea of what is needed for any form of astrophotgraphy.
If you decide that you really, really want to jump into astrophotography then by all means do not let this blog post be your only guide. Get books on the subject, read up on camera theory, and most importantly, talk to people in your local astronomy club. These folks are more than happy to talk about their hobby and the equipment they use. They are a resource, use them!
Happy Starshooting!
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