|
Ziguy
super member
Reged: 07/03/06
Posts: 105
|
|
How the optic of the EXT-80 compares to the Orion/Skywatcher ShortTube 80?
I bought a Skywatcher short tube 80 a few years ago and I was disapointed by the high CA. The ETX will be a bit better?
|
jgraham
Postmaster
Reged: 12/02/04
Posts: 6763
Loc: Dayton, Ohio
|
|
Hmmmm, they're both 80mm f/5 achromats, so all things being equal the CA should be the same in both scopes. A minus violet filter should help quite a bit without a significant loss of light.
--------------------
-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
|
caheaton
super member
Reged: 05/26/09
Posts: 159
Loc: SW Ohio
|
|
I own the ETX-80, but being my first refractor I have nothing to compare it to. I will say that I don't find the CA to be at all objectionable, but a V-block filter does sharpen the image of bright objects such as the Moon and the Sun.
Craig
--------------------
Craig
Ancient Tasco 4.5" (from back when Tasco's were good)
Meade ETX-80
Orion XT10i
Meade Super Plossls 6.4, 9.7, 15 & 26mm
Meade #126 Barlow, Opt(GSO) 2.5X short barlow
Zhumell Z Planetary 3mm
Agena Ultra Wide 30mm
|
brianb11213
Carpal Tunnel
Reged: 02/25/09
Posts: 2114
Loc: 55.215N 6.554W
|
|
Quote:
being my first refractor I have nothing to compare it to. I will say that I don't find the CA to be at all objectionable
OK, but don't look through a Newtonian, a catadioptric scope or even an apochromat, because you'll find the false colour hard to live with once you've seen through a scope that doesn't have it.
Short focus achromats are ideal for wide angle low power views of deep sky objects and work very well on the Sun when used with a narrowband filter (Baader solar continuum); otherwise the compromises do come with a performance price. Minus V type filters do help on moon & planets but these small scopes don't have a lot of light grasp to start off with & throwing light away is not something that can be done lightly.
|
Treehopper
professor emeritus
Reged: 07/29/08
Posts: 582
Loc: Upstate NY
|
|
Quote:
OK, but don't look through a Newtonian, a catadioptric scope or even an apochromat, because you'll find the false colour hard to live with once you've seen through a scope that doesn't have it.
Well, let's see...I've looked through plenty of newts, currently own a fairly decent cat, and at one time owned a military-grade 4" (around 100mm) air-spaced apo triplet. Each scope brings its own "personality" to the table when you use it, and you either adopt a "warts and all" attitude toward them or don't use them.
As far as the OP, I understand both to be comparable. Meade and Orion both have similar fabricating standards, both very likely start with the same crown and flint blanks made from the same materials, so you will probably get similar results from both instruments, at least optically.
The difference for me then came down to the choice in mounts and in portability. The Meade ETX-80 comes self-contained on a working GoTo mount which by virtually all accounts is very reliable. The whole package (scope, mount, and tripod) all come in at roughly 5kg and wraps up in a nice, tidy bundle for storage and travel. By comparison, if you stuck with Orion (which is a very good brand, I have no axe to grind with them personally), you'd probably have to get a EQ mount, pay quite a bit extra for dual-axis motors that would fit said mount, and while you would have tracking, you wouldn't have any GoTo capability.
Now, GoTo is not the be-all, end-all to astronomy, and I spent a good many years hand-slewing and tracking objects. But if the scopes themselves are neck-and-neck in quality, then the rest of the measure would have to come in the rest of the package (the mount), and in this regard, dollar-for-dollar and feature-for-feature, I believe the Meade to be the better value.
That's my two cents' worth anyway. 
--------------------
Tim
Champion of small aperture scopes everywhere!
Meade ETX-125PE
Meade ETX-80
Celestron FirstScope 76mm Mini-dob
 Updated: 09/16/2009
|
caheaton
super member
Reged: 05/26/09
Posts: 159
Loc: SW Ohio
|
|
Actually, the ETX-80 isn't my only telescope. It's my only refractor. My other telescope is a 4.5" Newtonian (F8), so I am familiar with views that are free of color. That was the baseline of my comparison...the CA in the ETX80 simply isn't enough to be a problem. When it does occur, the V-block filter eliminates it and sharpens the image.
Craig
(Just happened to think, I have a cheap Ramsden 25mm EP I use with the Newtonian as a finder EP...it has more CA then the ETX combined with the Super Plossls.)
Edited by caheaton (07/08/09 09:36 AM)
|
caheaton
super member
Reged: 05/26/09
Posts: 159
Loc: SW Ohio
|
|
Just thought I'd also add that I agree with Treehopper (Tim) about Meade offering a better value. It comes as a complete and very competent package. But if you want a more rigid mount that can also be used with other scopes, or prefer Equatorial over Goto, then the Orion would be your choice. I too considered the Orion, but I wanted a scope that would be highly portable and able to point to objects quickly (to maximize my time at the park on those 2AM weeknights  ), so I chose to get the Meade. I've owned it for a month now and have been very happy with it. It does surprisingly well on DSO for its size and also affords nice, wide views of the Milky Way and other star fields. It's become my primary scope.
Craig
|
AlienFirstClass
professor emeritus
Reged: 02/13/09
Posts: 742
|
|
The ETX series is an excellent grab and go scope choice.
|
AlexDJ30
sage
Reged: 09/02/08
Posts: 276
Loc: Monterrey, Mexico
|
|
Well between the 2, i think the Orion refractor have a bite more quality mechanically speaking , of course the ETX comes with Go to, something that the Orion short tube doesnt have.
If you want wide views of the sky, moon and form time to time jupiter and saturn its a good scope, if you want to do planetary vieweing most of the time and DSo in second hand i would not go the ETX-80 way.
--------------------
Equipment:
- ETX 125 AT
- C6 ASGT
- WO 66mm SD
- 2.5X ED Barlow, 8-24mm Zoom Eyepice
- Canon EOS Rebel XSi
- Celestron Nextimagen
- Orion Starshoot CCD cam
|
|
0 registered and 2 anonymous users are browsing this forum.
Moderator: Shadowalker, oldsalt
Print Thread
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Thread views: 616
|
|
|
|
|
|
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
[Re: 