Deep Space Astrophotography
I thought I would give you a brief look at how an Astronomy photo is taken. For Deep space atsrophotography it is not just a matter of connecting a camera to a telescope and taking a picture. You could do this but you would end up with a very dark photo as no light would hit the camera sensor. You need a camera that can have its sensor left exposed for long periods of time, most DSLR cameras have this facicilty and a telescope with which is mounted on a mount with tracking capability to enable the scope to follow the target. If you do not have this you would end up with Star Trails for anything over about 180 seconds of exposure. I use a special Astronomy Camera taht also cools the sensor to prevent overheating and noise on the image.
Assuming you have the mount, scope and camera then its easy ! Set up for the night and take at least 15-20 photos of 10-15 minutes exposure and you could end up with some useful data to make a picture.
Below is an image of the Veil Nebula I took last night, its actual 7 x 20 minute images stacked in software called Deep Sky Stacker. This gives you an image equal to 2hours 20 Minutes exposure. Waht do you get? an image thats mainly black with few white stars !
So what Happens next? Well This image is taken using a Filter that basically takes Black & White Pictures. To make a colour Image I will repeat the exercise of taking the same image again using Red, Green & Brown Filters for a similar time giving me a total of about 10 Hours of Data.
Using Photoshop on the above image I will adjust the Image drawing out the light data that has been captured using certain methods in Photoshop. Do not think I am drawing the image , all that is ahppening in is the computer extracting the light in the image so a picture appears. This is done with the Red/Green and Blue images as well and they then get layered on top of each other to create a coloured image. On this occassion I have only captured the main image using a filter that captures all light, not just the colours. The Image below shows the what the above images is like once strechted/processed in Photoshop.
The Veil Nebula is sometimes called the Witches broom. I have unfortunatly not framed this image well as the "Broom" should be more Horizontal. I will be spending more time on this target and a full colour image will follow soon.... that is if I get some clear nights !