Subexposure Times
I don't believe I have come across a topic that causes more contention and tension on the various forums than the subject of optimum sub-exposure time, and with it the total exposure time needed for acquiring a great image For sub-exposure times there are two boundary conditions, the lower bound and the upper bound. The lower bound is the shortest sub-exposure you can take before the CCD noise becomes the predominant source of noise. For the Hyperstar system and SXV-H9C camera with IDAS LP...
Narrowband Imaging and Light Pollution Filters
As mentioned previously, I always have an IDAS LP filter in the optical train. This filter cuts out emissions from common light-polluting sources sodium and mercury vapour lamps and as a bonus I find I do not need to radically alter the colour balance of my one-shot colour images. I have tried other nebula or light pollution filters and have found it necessary to make substantial colour balance changes to get a good colour-balanced image. Also mentioned previously was the Hydrogen Alpha...
Takahashi Sky 90 Refractor
For the Sky 90 refractor there is the native f 5.6 telescope, or with the Takahashi reducer corrector we can convert this to an f 4.5 refractor. The parameters for the various combinations are as below CCD F F.O.V. arc minutes Sampling arc seconds SXV-M25C 5.6 160.7X107.1 3.19 SXV-M25C 4.5 200X133.3 3.97 We can see that the short focal length of the Sky 90 makes for a nice wide field imaging system. Wide field imaging at reasonable sampling make these combinations look appealing for those large...
Celestron Nexstar 11 GPS SCT
For this reflector, the mirror diameter 11 is 280 mm, and the focal length in its normal mode of operation as a Schmidt-Cassegrain telescope is 2800 mm which gives us an f 10 system in the normal mode of operation. We can put an f 6.3 reducer corrector R C on the eyepiece end of the telescope Celestron make these R C elements and this will reduce the effective focal length to 1764 mm. There is also an f 3.3 R C available made by Meade and this results in an effective focal length of 924mm....
Prdttfal
Patrick Moore's Practical Astronomy Series Navigating the Night Sky How to Identify the Stars and Constellations Guilherme de Almeida Observing and Measuring Visual Double Stars Bob Argyle Ed. Observing Meteors, Comets, Supernovae and other transient Phenomena Neil Bone Human Vision and The Night Sky How to Improve Your Observing Skills Michael P. Borgia How to Photograph the Moon and Planets with Your Digital Camera Tony Buick Practical Astrophotography Jeffrey R. Charles Pattern Asterisms A...
How did I start
This Chapter may help if you are just starting out in deep-space imaging. Personally I find it very useful to see how other people entered the hobby, because in that way you can see what their major mistakes were, and hopefully you can then circumvent the major problems. I am fortunate enough to live in a semi-rural location with reasonably dark skies. I was also in the fortunate financial position of being able to buy myself a reasonable quality telescope. At this point in time, around...