Orion Europa 250mm, F4.8 Newtonian reflector.
http://www.orionoptics.co.uk/
For good images the aperture of the telescope seems to dictate the quality of the final picture. The larger the clear aperture, the better the picture. The images are degraded by seeing conditions, vibration or wobble of the mount, poor focusing and IR bluring (on sun spots). However, I have now replaced the original GEM mount, that was far too flimsey, with the Skywatcher EQ6. This has made a lot of difference to the quality of the images. I have also changed the focuser to a two inch Crayford and replaced the 2-bar spider with a four vane spider. This has removed the two big diffraction spikes and replaced them with the more astheic and traditional four star spikes.
I use an apodizing filter on the bright planets to supress distortion brought about by atmospheric turbulence.An apodizing filter is a alternative to stopping down the telescope's aperture. The advantage is that the telescope can still resolve the detail at full aperture. The image does become duller and the screen produces some colourful deffraction paterns. Luckily, these patterns are outside the filed of view for the CCD chip.
Apodizing screens are discussed in detail on the following web page and in the Planetary Observers Handbook, Fred W. Price, State University of New York, Buffalo (ISBN-13: 9780521789813 & ISBN-10: 0521789818).
http://home.digitalexp.com/~suiterhr/TM/apodize.htm
Web Camera
Philips ToUCam Pro webcam.
The camera needs to be slightly modified before use. Firstly, remove the lens and then add a purpose made thredded adaptor to fit the focuser barrel. I also use an IR/UV block filer to prevent dust collecting on the face on the CCD and to help resolve detail on sun spots.
When taking images from the web cam, be sure not to set the shutter speed too low. Its always possible to bring out detail if the image is dark but detail is lost forever if it is ove rexposed.
For most planets, you can take your time downloading the avi at moderate frame rates. However, for Jupiter, you need to download as fast as possible as the planet details move suprisingly quickly afffecting the final image with bluring. I typically download at 30 frames per second for 30 second, resulting in an avi containg 900 frames.
Solar imaging requires a certain amount of precaution and it is very important to use a solar filter over the aperture end of the telescope. I use a full aperture Baarder filter.
The web cam is fitted with an IR/UV block filter to help sharpen focusing for sun spot work and also to prevent dust settling on the CCD.
The camera is ideal for prime focus or with a Barlow lens. However, for an f4.8 system a higher magnifaction is required for planetary work. This is acheived by eye piece projection. Although there are specialized eye piece projection tools, I use a cheaper solution. The picture below shows the web cam fixed to a 10mm eye piece by using a plastic plumbing pipe joiner.
In order to move away from this set-up, I have purchased a 4x barlow that allows me to get almost the same magnification without the need for eye piece projection.
DSLR
I have recently purchased a Nikon D50 and I am still experimenting with it's capabilities. The original rack-and-pinion focuser on the scope was not able to rack far enough in to use the Nikon while at prime focus. However, the problem was solved by moving the primary mirror about an inch up the tube. This was a very simple process and just involved the replacement of three short screws with three longer screws on the mirror cell.
Focusing with a DLSR is always going to be an issue as the target object is inevitably far too small and faint to be clearly visible in the small LCD previewer a the back of the camera. There are some very precise and expensive focus aids such as knife-edge focusers and Ronchi screens. A simple Hartman mask will get you close to focus and then a little bit of trial and error to reach final focus. Most DSLRs will have accompanying software that will allow you to control the camara from a laptop. This means that you can preview you image on a large screen and is a good way to reduce the amount of test images that you need to perform.
I would also recomend a mains power adapter for the camera as you will easily drain a couple of battery packs during a night's observing.
Dell Precision Laptop. 2.4GHz, 1GByte RAM.
The main requirememt for the computer is that is able to download at images at around 30 frames per second. Any new computer will suffice. The laptop does not have USB2 ports that are desireable for faster download speeds. However, a 2-port PC card can provide USB2.
Software
VirtualDub is a free program that enables you to edit avi files that are produced by the web cam. It is crucial, from a speed perspective, to convert the avi file so that it uses IYUV compression. It will reduce Registax processing time from hours to minutes.
http://www.virtualdub.org/
The Registax software is an amazing tool that averages and enhances frames from an avi file taken by your web cam. All the astro pictures on this site have been generated in this way. This program is freeware and available via the link below.
http://www.astronomie.be/registax/
Registax has a lot of controls and options that are described in its help file. However, good images can be generated without paying to much attention to getting these settings absolutley correct.
http://www.gimp.org/
Final image enhancement is done in a graphics packeage like Photoshop or Paintshop. Although these packages are not free, there is an open source program called "The Gimp" that has all the functionality that you need.
I use the the "Unsharp Mask" in Paintshop Pro 7 to squeeze the last bit of enhancement from the image. Then I use the colour tools to make the images more vivid and less "washed out".
DeepSky Stacker is a freeware program that allows you to average a number of images in order to increase image fidelity and reduce noise. It also allows darkfame subtraction. This is essential for use with my DSLR as thermal noise from the electronics cause a red-pink bloom to appear on the image.
http://deepskystacker.free.fr/english/index.html
