Virtually all deep sky objects are quite faint and you cant get images of them by simply pointing a camera up to the sky and pressing the button. In order to capture the faint light coming from these objects, you need to take long exposures (of at least 30 seconds). With this in mind, I need to use a camera that has the ability to take very long exposure lengths (aka bulb mode). The camera also has to be of the SLR type so that original lenses can be taken off and the camera body be attached to telescopes via an adaptor. The Canon 400D fits well in to this category well.

The next hurdle is the movement of the sky. The Earth's rotation causes the whole sky to move. The stars rise and set just as the sun and moon do. This means that taking a long exposure of the sky at night makes everything blur in the picture. This is because in the space of 30 seconds or more, the sky has moved a little. To rectify this, the telescope is placed on an equitorial mount. This is more of a glorified heavy duty tripod with motors. Its aligned with a certain point in the sky which then means you can turn the motors on and the telescope will follow its target as it moves across the night sky

When imaging at high magnification, things can get quite tricky. The slightest foreign movement of the telescope will ruin an image. A windy night can postpone an imaging session if its strong enough to move the telescope tube even a fraction. You cannot press the button on the camera, it has to be done remotely. I have two methods for this, one is an infa-red remote control and the other is by use of a laptop and camera control software. Other measures are taken to prevent vibration while the camera opens its shutter/mirror. A simple setting called mirror lock up is set in the camera whereby the camera moves the mirror inside then waits a couple seconds for vibration to settle before opening the actual shutter.

I use software on the laptop called ImagesPlus which lets me choose my exposure lengths, camera settings and choose how many images to take. It will allow me to choose unlimited exposure lengths over 30 seconds (A second serial cable is required to do this). This is great as it allows me to take for example 30 exposures at 60 seconds each and I wont need to press a single button to take them all.

I hear you ask, why take multiple shots of the same thing? In an ideal world, we would take a single shot of our target lasting hours. There are a number of reasons for not doing this. Firstly, digital camera's suffer from 'camera noise' which worsens with longer exposures due to the heat created by the digital sensor chip. It is also very hard to get your telescope to accurately track the sky for such lengths of time, it would take incredible accuracy. My mount for exmaple, when using my large telscope can accurately track an object for around 90 seconds before the stars start to 'trail' on my images. There are other factors like light pollution. This can quickly limit exposure length before the image suffers from too much orange glow. Also, satellites and plane lights sometimes fly through the frame shot. With all this in mind its best to take short exposures and take a lot of them. With digital imagery these shorter images can all be stacked together which bring out the required detail.

Without boring you to tears, I'll keep this short and sweat. The images are captured in RAW format. This way the image has not been adjusted or tweaked by the camera. The images are stacked together and tweaked in many different peices of software with different uses. I use ImagesPlus, Adobe PhotoShop CS3, PixInsight and PaintShop Pro.

Browse through the deep sky section of the gallery and you can be the judge!