i am torn between an 8 inch dob or a 4 inch refractor- am experianced- like refractors-but want more light too

Question

Experianced amateur but out of it for a few yrs- have had dobs n Eq's -I love drawing jupiter- still have a 6 in f10 dob that needs recoated in basement- also have a 12 in f10 superplanetary optics set that i never built the scope for-
money limeted or i'd get 'em all-

Answer 1

Hi. The reflector has both advantages (light gathering, lack of chromatic aberration) and disadvantages (coma, diffraction around the secondary and struts). Good (read as expensive) 4" refractors have a potentially sharper image but focuses different frequencies at different lengths. Have you considered a Maksutov? Some of the advantages of each. (My scope is a 6" Schmidt-Newtonian, nice images, f5.)

Answer 2

I built a 10 inch Dob, and then built an Equatorial Platform to use with it to compensate for the earth's rotation. It makes observing, and especially sharing observing time with others (family and friends, for example) much easier, because when you have the scope aligned on an object, the platform will cause the object to stay in the field of view, even at fairly high magnifications.

You can learn a bit more in a couple places:

http://www.geocities.com/birchardvilleobservatory
and follow the links to astronomy, and then to telescopes
and equatorial platform topics.

The Yahoo Group, EQPlatforms, has a lot of information
on building or buying a platform that would work like mine.
That's where I got most of the information to design and
build the platform I made.

I'm sure you'll want some sort of tracking mount. For the
refractor, a German Equatorial mount is common, but
they are more expensive when they are of high quality.

Answer 3

I'd go for the 8" dob. I'm saving up for an Orion XT8, they've gotten very good reviews.

Happy stargazing!