Expert: Paul Wagner - 4/3/2006

Question
I know the optics of the different types of scope but I hope you can answer a question that's been at me for quite a while. Given that a reflector has more aperture (even considering the secondary) for the money, and given identical quality, why do people spend $5k for a Tak 4" OTA when they can get a 14" cat or newt with mount and drives, the whole thing for the same or less? I've been told over & over that deep sky requires aperture, and a 4" refractor just has less of it than a 12" or 14" reflector. The pictures I've seen seem to prove that it's worth the money, but nobody can explain the performance vis-a-vis the smaller aperture. Hope you can explain. Thanks.

Answer
Dear Tom:

You are asking the wrong guy.  I have four scopes--reflectors from 4.25 to 17.5 inches in diameter, and one refractor that's a 3" one.  There is no comparison.  And for what most amateurs want, the reflector is simply a better choice.  I sometimes use the refractor as a finder or guide scope on my large reflector.

But if you are doing astrophotography, the mounting of a small scope is easier--and more reliable.  And the magnification is easier to manage as well, when you are only talking about 150X or so.  That can make for some nice photos of Saturn.

And those high end refractors appeal to the little boy in all of us, who wants the scope like the Yerkes 40" that he grew up adoring.  And Yeah, they are really nice.  But If you have ever seen some of the great planetary photography with 8" long focus reflectors, you understand that this is vanity, not common sense.

Then again, who ever said that hobbyists should always use common sense?  That's what makes it fun!

Paul Wagner