|My astrophotography home in Chiefland, Florida, a 10 foot dome (center) that houses my equipment. Left is a roll off roof observatory belonging to a friend, right is a pod dome belonging to another friend.|
DEEP SPACE – THE FINAL FRONTIER
Two types of mounts - (L) Altitude-Azimuth mount; ® German Equatorial Mount.
|Celestron Advanced VX mount - $799 new, less if you buy used.|
All of the mounts in the $500-$1500 price range are motorized and come with a "Go To" feature. "Go To" mounts allow you to select a target from a menu on the hand controller, push enter, and the mount will automatically slew the telescope to the selected target.
|Screenshot of Stellarium software after a search for "Great Nebula in Orion"|
|Stellarium screen shot showing what you get when using the "ocular view" feature for a target. In this case, the target is the Great Nebula in Orion.|
If Stellarium isn't your cup of tea, Cartes du Ciel is another free planetarium program you can try. You can also go to http://freeware.intrastar.net/planetarium.htm for a list of many other free astronomy programs available for download.
Learning To Walk
|Sky-Watcher Pro ED80, a good, starter 80mm refractor suitable for astrophotography. 600mm focal length @ f7.5. Expect to pay approximately $600 new, less for a used one.|
|Wide field image of the nebulae in the constellation Orion. Orion’s Belt is the diagonal line formed by the three blue stars on the left, ending with the blue star in the center nebula.|
Above is an example of what is possible with a similar setup, including the accessories. I shot a total of 160 images at various shutter speeds ranging from 10 sec to 45 sec at ISO 1600, and 10 images with 1-3 minute exposures to layer in a sky saturated with stars at the end of the Photoshop process. Before wrapping up, I shot ten “flats” at each shutter speed, twelve “darks” (half before starting the imaging process of Orion's nebulae and the other half at the end of the imaging session) at each shutter speed, and ten “bias” frames for the pre-Photoshop processing in software that “stacks” the images together.
Say What???? Flats, Darks, Bias Frames and Stacking???
“Darks” are images taken by covering the end of the lens with the lens cap. Half of the darks are taken at the beginning and the other half at the end. Darks correct the dark signal flaws in image sensors.
“Bias” frames are images taken with the fastest possible shutter speed the camera can shoot and the lens cap on. They contain only the noise generated by the camera’s electronics on the sensor and is subtracted from the data in the darks to identify the true sensor noise. These extra images are time consuming but they will allow you to create the best possible final image.
All of these images are used in the pre-Photoshop processing of images in software that is commonly known as "stacking" software. Darks, flats, and bias frames will be covered in the next post (Part IV) of this series; stacking will be the topic in Part V.