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Comments/help on new scope plan please...

Started by erik_hammarlund, 07/25/2005 06:36PM
Posted 07/25/2005 06:36PM Opening Post
I'm finally moving to a relatively decent location. Not the darkest skies, nor the clearest (Martha's Vineyard) but I've got a big field and unobstructed views right near my house, so I look forward to viewing a lot more.

So far, I've only owned one large scope---my first: a ~1988 Celestron cardboard tube 8" f6 Dob, single vane. It's functional though sometimes hard to collimate. And the mirror is getting a little dull.

Sadly I learned that my wife and I often like to look at planets, and tracking at high power is a royal pain in the arse. In fact--and this will be no surprise to anyone--ANY tracking is a pain if you're at the wrong angle. Also, I like my kids to look (or other slightly inexperienced friends) and they either bump the tube, try to move the tube and lose the object, or both.

OK... So I need a decent mount, with electric tracking. That's clear.

In terms of the OTA, I want a scope that will allow me to look at planets with high power, and without using 3mm eyepieces and barlows. I've gotten OK results with my 48" focal length dob; i can't see going a whole lot shorter than that; this seems to eliminate most of the short focal length apos. Of course (it's never easy) i _also_ would like to be able to use it to look at smaller deep sky objects, if possible. yes, I know I am asking for two different things. but I'm trying to figure out the 'ideal' focal length is. Even with a 6' scope, i'll be able to view the entire moon using a ~25mm eyepiece (since I can do that now with an 18mm and a 48" scope). Or am I calculating wrong?

OK, that's what I want. now here's what I'm thinking of getting:

I'm leaning heavily towards an Atlas or c6 mount. I don't especially mind the weight, as I don't plan to travel much with my scope. I'm _never_ going to do photo (or if I will i'll just upgrade then). I don't care about goto for now. And I want it to be solid at high mag. Finally, I want to be able to stick other scopes onto it, now or in the future, so I don't have to constantly switch mounts. I know I'd look funny with an 80mm on an Atlas, but I'd rather avoid spending more $$ on a separate mount. I can't afford a gm8. Sensible so far?

For an OTA, I'm really debating between two things: an Intes or Intes Micro maksutov, and a D&G refractor.
Price wise, a D&G 5" is $1600, 6" is $1900, in f12 or f15. The 6" f10 or f12 intes scopes are $1300; the Intes Micro 703 is $2100.

I can imagine the difference in portability, of course--a Mak wins, hands down. But how about cool down? How about viewing? Light transmission? I'm leaning towards the refractors (I am not going to search for a tiny violet fringe to complain about; not my style). I'm guessing that I'll still be able to use a long 2" eyepiece in the refractor to get lower mag, though maybe I'm wrong about that as well...?

i'm guessing there isn't really any mount savings either way. Maybe I could get a GP instead with a 6" mak, but it's not really any cheaper, and I know I don't want a cg5.
Help! Any comparisons or comments would be welcomed.
Posted 07/25/2005 07:27PM #1
Erik
Instead of a tracking tripod, why not a good 8" to 10" dob (pick one) on a tracking platform. Get the best of both worlds aperture and tracking. You might still have to tie their hands so they don't grab the scope but they wouldn't have to touch it to track.
Just a thought
Buck
Posted 07/25/2005 08:22PM #2
I agree with John. A long 5- or 6-inch acromat will require a more substantial mount. An Atlas or C6 is simply not up to the task -- not tall enough, either.

I'd get the biggest Maksutov both my budget and mount could comfortably manage -- likely from either TEC, Intes, or Intes Micro. If my budget &/or mount dictated a six-inch Mak, but I still wanted more aperture, I might very well opt for the Celestron 9.25.

Cheers & best wishes.
-Dan
Posted 07/26/2005 12:16AM | Edited 07/26/2005 03:06AM #3
Couple quick comments:

I owned a D&G 6" F15 on a G11 for a couple years. The G11
is barely adequate -- not stiff enough. Slight breezes
result in large image motions at the eyepiece -- the
long tube made it very sensitive to wind. Height
was not a problem; you get the half-pier extension and
put some extra weight on the back of the scope (Telrad,
finder scope, some big slding weights) and it shifts the
balance point rearward. Gave really nice images even in
marginal seeing conditions (no tube currents, no heat from
observer, etc.). Chromatic aberration not too bad.
Not exactly "grab & go."

I owned a Intes MK67 for a couple weeks. Superb optics.
In real-world planetary observing it was pretty close
to a 4" APO at a small fraction of the cost. But therein
is also the problem -- I thought it was disappointing for a
6" scope. The slow cool-down, large central obstruction
didn't help. Some of the high-end Maks have vents and
fans, but will be pricey.

Someone suggested a Mak-Newt. This is a good suggestion.
I'm pretty happy with my 6" Intes-Micro MN61. Small
obstruction and modern ones have vents and fans. Nice
optics. Performance is close to a similar aperture
refractor, no false color, reasonable sized instrument.
Get a TeleVue 3x Barlow to use with it, if you want
more eyerelief.

SCTs -- again cooldown and large obstruction are
issues for planetary viewing. My C9.25 has great optics,
but seldom reaches its full potential due to cooldown issues.
I think these probably do best in some place with small
day/night temperature swings (Florida, etc.).
Posted 07/26/2005 04:53PM #4
Given your criteria I strongly suggest that you explore an 8" or 10" SCT like the LX90 as it would come in at your price range, would be stable, have computer guidance, a long focal length for viewing planets and plenty of light gathering ability. Also compare the weight of the Meade and Celestron SCT's as there are some differences to consider.