This is what it should become:

• Mirror: 15 or 20cm, grinded by myself. Because I have no grinding experience whatosever, we play it safe and choose a 15cm.
• Optics: f/8 Newton: the light of the main mirror is deflected by a (flat) little mirror towards the ocular. A drawback is that the little mirror is in the way of the light falling onto the main mirror. But the little mirror isn't too big, so the loss of light is not that bad. The f/8 indicates that the focal length is 8 times the mirror diameter, in this case this is 8x15cm = 120cm. Mirrors with small f-numbers (e.g. f/5) are called fast mirrors; mirrors with large f-numbers (f/10) are called slow (surprise). These names have something to do with exposure times when you do astrophotography. (See also the ATM FAQ.)
• Mount: altazimut. This means that the scope can turn around two axis: left-right (azimut) and up-down (altitude). The reason for choosing altazimut is that I want the construction to be mechanically as simple as possible. The drawback of this approach is that following is more difficult using a motor. This is because the stars apparently describe circles in the sky, so we need to rotate on both axis, as opposed to other mount types where only one axis turns, but the construction is somewhat more elaborate. This is not a real problem since I want to have computer steering anyway. This under the motto keep the hardware simple and put the complexity into the software. It's much simpler, cheaper and reliable to make complex software than complex hardware. It appears that we need an accuracy of about 4 arcseconds for astrophotography.
• Computer steering: I want to revive my old laptop (its poor harddisk died recently) and to drive two stepper motors via the parallel port (one stepper for left-right and the other for up-down). Maybe I'll install a third motor later to rotate the camera around its axis (to compensate for the so called field rotation), but for the time being I won't install a camera, so that can wait. Moreover, I intend to install a CCD camera, and then we can rotate the camera image in software (see the motto above).
  Nowadays you can find more star catalogues than you can dream of, and it would be of course very nice to put such a catalogue into the laptop and hook it up to the telescope steering program. In other words, the laptop shows a star map, on which you walk around and the telescope turns automatically to the indicated part of the sky.
• CCD-camera: to make nice pictures, of course :-)
  Combined with the computer steering, we can track with more precision, because we can check if the motors have turned far enough just by looking at the images the camera sends back.
  A CCD camera has some advantages compared to a classic camera: the CCD camera catches more light, and you can do a lot of stuff purely in software. An idea is to have a look what is possible by not exposing the CCD one long time (say 15 minutes) and then reading out the CCD, but taking a lot of briefly exposed images and than add them up by ourselves. What can we gain by using this method? We can correct each separate image; a simple kind of correction is to make sure that the stars don't `move' (because the tracking was not precise enough, or somebody hit the telescope, I don't know) by moving the images a little so that they are all exactly aligned: More advanced possibilities are maybe dropping `bad' images (whatever that may be, e.g. if temporarily the image is obstructed by clouds or passers-by). Maybe we'll get it one day to the point that we can compensate seeing (jittering and deforming of the image because the air in the atmosphere itself is unstable). Another possibility is to do some image restoration: if we know the errors of the optics precisely enough, we can calculate an `ideal' image without those errors out of the image we see.
  Of course we don't buy a ready-made (expensive) CCD camera, but we buy some cheap CCD chip from the electronics store and see what we can do next. A problem is that those CCD's tend to generate a lot of data, and the laptop needs to read that in fast enough (even small CCD's have 512x512 pixels and we need to push them all through the parallel port). Maybe we can help a little by connecting a small processor (a microcomtroller) to the CCD that compresses the images before sending them to the laptop.
• Cooling for the CCD: It appears that CCD's generate noise on the images when they are too warm, so we have to cool the thing. There are Peltier elements available which we could try out (those are things that become cold on the one side and hot on the other when you put electric current on them).