4" TV-102 kicked 8" Discovery Dobs

http://members.cox.net/ronby/Observations/TV-102-kick-Dobs.htm

Ron B[ee]

Ron, your comparison has one huge inconsistency - the optics in the two scopes are not equal.

An accurately-collimated, cooled-down 8" dob with, say, a Zambuto, Royce, or other high-quality mirror will just flat out beat a 4" APO in every category - DSO, planetary, splitting tight binaries. It will easily beat the 4" APO in mediocre seeing and in good seeing. It will give you those aesthetically-pleasing "APO-like" views with no problem at all. This is just a fact.

Ron, comparing your 4" APO to a mass-produced 8" dob is comparing small apples to big oranges - and the results are predictable. You observed exactly what one would have expected. Your results will be different if you compare your 4" APO to a smooth-operating, well-collimated dob with a high-quality mirror.

Doug

Hi Ron,


I can only speak from my experience where my Teleport 10" consistently revelaed more planetary detail and split tighter doubles than my AP 155. I do not know what type mirror or the quality of the mirror in your dob, but the Zambuto in the Teleport was great.


Marc Zukoff

I all fairness the Televue 102 costs more than 4 times what a Discovery dob does (unless you want a mount for the Televue). So it should walk all over the dob, if money has meaning. Of course, we both know what's going to happen in good seeing and dark skies. And, naturally observers should optimize their scope to the conditions where it will be used.

Ron,

Nice field report! One disagreement--some achromats are formidable. My 6" F/15 D&G refractor is indeed massive, but was relatively inexpensive (purchased used for less than a TV 102) and is extremely sharp. Color is minor, IMHO, and only visible on brighter objects.

Clear skies to you and your TV102 and new dob,

John Harrington

Wow, this is a huge thread!

I wish I had time to read everyone's responses, but I'll just put my 2 cents and hope I'm not repeating anyone

I read your review there Ron, it was actually a good review!
I personally can totally relate to what your saying, I think it's alot of what we get used to. We started with a 6 inch Newt, and with that size, usually the stars look pretty good but at high power are a little like **. But then we got a 90mm ETX, and the star test is perfect in it, now false color, the stars are dots like a refractor, but my complaints were that everything is so DIM! Our 10 inch, stars are more like asterixes, but man, globs and nubulas show so MUCH more! I think your lucky though, now you have the best of both worlds! Hope you learn to like collimation though, I actually have fun with doing it! I have it down to about a 45 second deal and maybe a couple minutes for fine collimation on a star. :-)

If your dob moves stiff and it's hard to track, in case no one mentioned this, make a couple washers from a milk jug and put them around the center bolt, I did that and now I have to troubles moving it fine amounts even at almost 300X!

Take care!
Ron S

Hello Everyone,

It appears that the title offended some people. Since this was the furthest thing from my mind, I'd like to offer an apology to those who felt offended. You'll notice the new title.

I also to like to thank everyone for the comments, especially those who provided tips.

Ron B[ee]