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Welcome to the ASIGN Astrophotography page, for ease of navigation I have created 8 individual sections, which all contain images I have taken using the equipment listed below. When you click on the area of your choice, a new browser instance will open which will contain its own unique naviagation system. All images will originally appear as a thumbnail and when you click on any thumbnail image, it will open up to it's full size. Where possible I have tried to keep the size down without compromising the quality of the image itself.
My Astrophotography Equipment
Camera:
Canon EOS 400D Digital SLR
Optics:
Celestron Nexstar 11 GPS Schmidt Cassegrain Reflector (F/10 Focal Ratio)
Skywatcher Pro Series ED80 Apochromatic Refractor (F/7.5 Focal Ratio)
Methods of image capture:
Piggyback on top of aligned telescope, prime focus photography via T-ring and camera adaptor through the telescope, added eyepieces inside camera adaptor.
Photography configurations
Camera and lens piggyback.
This is a method employed for using your camera for shots by itself. The advantage here is that if you have a polar aligned telescope that can track the movement of the stars, then you can have long exposure photographs. This gives faint light more time to burn an image onto your film or chip, without suffering star trails.
All that is required is a mount, to secure your camera onto the telescope, using your telescope as a tracking platform only.
Prime focus photography.
Now you have practiced piggy back, its time to take the lens off the camera and use your telescope as a lens. This is done via a T-ring. A T-ring has a bayonet type fitting that is unique to your brand and model of camera. These are not available for all cameras, so make sure you can get one for the type of camera you want, before you buy it!
The other side of the T-ring has a fine thread that fits to the camera adaptor tube. This is just a hollow tube, that can be used on its own, or have an eyepiece secured inside it. (Thats another story, see below). The other end of the camera adaptor has a stepped-down tube, available in a couple of sizes, to fit the eyepiece holder of your particular telescope.
Once the T-ring and adaptor is fitted to your camera in place of a lens, all you do is pull out the eyepeice from your telescope, and drop the camera in.
To advance a little further on this, you can use a radial guider. This can be used in place of the camera adaptor for prime focus. The Radial guider is an off-axis setup. Simply put, it has the addition af a small prism that intrudes into the edge of the tube. This takes a tiny little edge out of the field of view (FOV).
You can then swivel your eyepiece and the prism inside, to pick up a guide star somewhere near your subject. You can then keep looking through this for the duration of your exposure, and make tiny adjustments to your telescope, to keep this guide star still. Once you press the shutter release, the flip mirror in your camera will not permit you to look through the camera anymore. For this reason, a radial guider is handy.
To focus your eyepiece in the guider, simply loosen the thumbscrews and slide the eyepiece in and out to get focus. This has nothing to do with the focus on the camera. Make sure you get that right first.
Zooming in for Eyepice photography.
The camera adaptor can be used for prime focus, basically just shooting through a tunnel to the lens (telescope). You can increase the magnification and make your target image look bigger by sliding different eyepieces into your camera adaptor. This makes the object look bigger, but makes the FOV smaller. It also makes focus a lot more critical. This can have advantages and disadvantages. Sometimes its better to keep the image smaller but sharper.
Shutter release.
Make sure you use a shutter release cable to prevent moving the telescope and camera in the image taking sequence. Alternatively you can hold up a black card in front of the lens or telescope, trip the shutter, wait for vibration to stop and take away the black card. Once the exposure time is up, hold the black card in front of the lens again, and release the shutter.
First attempt at Stacking and processing images from the new DSLR.
Today, I had a go with a program called DeepSkyStacker http://deepskystacker.free.fr/english/index.html
These two processed images were taken with a Canon EOS 400D on ISO1600 and comprising of 2 approximately fifty second exposures stacked with darks and bias/offsets - no flats.
The program has a good help file as I did these with absolutely no idea of what I was doing. I just played around with it to see what it did. I'm sure it can do a LOT better, with a bit of perseverance.
The telescope setup was via camera adaptor on prime focus on a Celestron Nexstar11GPS set on Alt-Az tracking mode.
Taken 18 April 07 from A.S.I.G.N. Observatory, Canberra.
Happy astro-imaging!
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