Astrophotography Project for Begginners Print
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Written by Corina Mihaela Paraschiv   
Sunday, 16 December 2007 01:36

One thing I really love to do is to go star gazing. On a night where it isn't cloudy, take the car and drive down to a place without too much light or distractions. I used to try and get friends along only to find that they were sometimes not sharing my enthusiasm about the stars. I later discovered it was better to have an activity to share together around it than what might seem to them like looking up at a bunch of random dots in the sky. So here's a project I've designed which can be done with your friends on a night out :  A great way to observe the sky is by photographing it. This enables you to isolate a part of the sky and distinguish some constellations. The adventure doesn't end with the picture taking; when you head back home, you can print the pictures and link the stars within a constellation using white ink. You can make this even more fun by trying to imagine what the greeks saw in the sky and by drawing it over the constellation.  Here is a step by step guide to doing it.


Taking the Pictures

For the photographies, you'll have to first select well-known constellations that you can already locate in the sky. The first shots I took when I did it were of Cassiopea, Ursa Major and the Dolphin because they are easily recognizable. I made use of a single reflex camera (35 mm) because the digital cameras with the settings we need are for professional use only (and therefore very expensive). So what you want to put your hands on is very old cameras that your grandparents may have stored in the attic.


   One thing about the Big Dipper is it's not actually a constellation.  The Big Dipper, which you see here drawn in golden, is actually what we call an aterism; a smaller, recognizable pattern within a bigger constellation

  What you see here is the actual full constellation of Ursa Major (or "the Big Bear).  Even then lines are going out of the drawing because I did not have enough space, but you nottice only the rear and the tail are represented by the asterism of the big dipper.


Camera Manipulation


Another thing to take into account is you need to make a long exposure (that implies you need to hold down the shutter button for some time, without trailing, which would be somewhere between 10 and 15 seconds) and it also means you have to put your settings right (I think it is the R position if I remember correctly). What do I mean by trailing, shutter, exposition time... You want your camera to be able to take a picture of the night sky. This implies two things. First, that the camera should be able to see the stars brightly enough (and a way you can do that is to keep your camera on a star long enough for it to imprint on your picture). Second, the stars move. So although you want to have a picture that clearly shows all the stars, you don't want to have your camera recording trails because you shot them for too long. The only way you can really be sure you're doing alright is by taking several shots of the same thing varying the times, and looking at home at your set to figure out how long you should keep the shutter button enclenched. The focus is also important when you handle your lenses because you have to focus it at infinity, because the stars are so far they look almost like at the infinite. Otherwise you'll get unfocused blurbs of light.


Last thing you want to consider is the practical consideration of “taking a picture” which is that you're zooming in on a part of the sky and any movement that you make will shake the camera and blur your picture. So pushing down on the shutter button with your finger is probably not a great idea. For this reason, we use a miraculous little invention called the cable release. It is basically a cable that pushes down on the button for you – and the beauty of it is it can stay enclenched for a long time without you needing to physically push it which, for one-hour-long trailing pictures, is great news.



Note that it is wise to keep a record of the field of view and of the constellations you took as you go – using a red light because white light will blind you and you'll be unable to see the fainter stars for some 15 minutes after – because it can be very difficult to tell afterwards what section of the sky you were photographying, specially if you don't have a sense of the scale. You don't actually need very zoomed in pictures either, because if you are working in a darkroom, you can manipulate it later. The dolphin picture I took for instance was croped, and then enlarged when I developped it. It was a way of putting it in evidence.



 Back Home


 When you're done taking the pictures, it's time to take them to the shop or develop them yourself.  The pleasure of developing them yourself is something you should experience at least once in your life; the excitement of waiting for the picture to appear on the photosensitive paper is really great.  You also have more flexibility, as you've seen with the example of the Dolphin picture, to bring forth what you need.  Most likely when you start though, you will be bringing your shots to a photo lab to get them developed.  Remember to specify to the employee taking care of your pictures that these are night shots of the stars, otherwise your pictures may end up not being developed properly (or at all) because technicians are used to develop birthday parties and family portrait pictures, not astropictures.  Always insist to double check your developed film if they tell you they didn't print it because it looked blank, because you are more likely to judge of whether that was the case or whether you still want it print because you can see the faint dots you took earlier on. 


In this first part, a lot of things may go wrong, because you rely heavily on technology for both taking the pictures, and printing them. The key is to have patience and to consult others who know more, in advance. Once these steps are over, it gets easier; you only need your imagination and a pen for the next steps.   Below you see what would happen if you forgot to unclench the cable release on time : star trails would appear, which would not be practical for the type of project we are trying to achieve.  This however is a 35 minutes exposure with maximum aperture and a 210 mm lense focused at infinity.  Chances are if you forgot it just a little, and with a wider lense, you would only see blur but not such clear trails.   

One of the advantages of this project is you will be able to see the magnitude (brightness) of stars relative to each other. Brighter stars will appear like bigger dots on your picture, and fainter stars will be smaller dots. Depending on how much you zoom in and out of the sky, you can also place the constellation in context to other constellations or other stars. With a zoomed picture, for instance, you'll learn to recognize the smaller stars you usually don't associate with those constellation, making it easier for you to track it down next time you're in “zoom-in mode” with your binoculars or telescope (although finders make the task a bit easier).

Last Updated ( Sunday, 16 December 2007 02:12 )