First to you, Denmark boy: I don't know where you read that an alt-az mounted scope is good for astrophotography or CCD imaging, cut they clearly are not. Your suspicions are confirmed. With the exception of the Meade LX200 and 90 series mounted alt-az with a specialized corrector, a straight alt-az scope is for visual use only. As the LX200 & 90 series start at around $1500US, this may well be out of reach to you at present. Dobs can be outfitted with an equatorial plate and a motorized drive, but this also runs into money. If astrophotography is something you think you would like to persue, then I would suggest you get a good reflector on a German Equatorial Mount(which is refered to as a GEM). Equipped with a motorized drive and a guide scope, these will take beautiful pictures. Orion has a very nice 8 inch on a GEM outfitted with dual-drives for both declination and right ascension for $598US that also comes with a CD of The Sky Version 5 Level 2:

http://www.telescope.com/shopping/product/detailmain.jsp?itemID=1148&itemType=PRODUCT&iMainCat=4&iSubCat=8&iProductID=1148

Take your time. Don't rush into purchasing a telescope(or anything else), best to be absolutely sure and not kick yourself later on!

Regards a 6" or 8" telescope, while the 6" is quite capable of showing you a great wealth of deep sky objects(DSO's in the trade), it is a well-known fact that the 8" will allow one to see far more detail. M13 is resolved to the core in the 8", whereas the 6" shows it as a fuzzy ball for example. The 6" would be a good choice if you were planning on mostly viewing the planets and other solar system denizens. But if you wish to go "far out", I would highly recommend the 8". The same is true of refractors. While a 5" refractor makes an excellent planetary scope, one would want a 6" for going way out there. This would cost around $1,000 to manage. This is one reason that most people opt for reflectors - either Dobs or mounted on a GEM - over refractors. More aperture for the money. In the last analysis: You would be happier with an 8", rather than a 6" scope.

Clear Skies,

Dave