Click here if you are having trouble logging into the forums
Privacy Policy |
Please read our Terms
of Service | Signup and
Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User
MattT
sage
Reged: 04/20/06
Loc: SF Bay Area
|
2" Diagonal for Nexstar 8SE
#5291667 - 06/27/12 02:07 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
About to order a Nexstar 8SE. I figure I'll use a 1.25" diagonal with it to start, at least until I see how happy I am with the scope, but I'll keep an eye open for a deal on a 2" diagonal.
I'm guessing I'd want the SCT-type diagonal with the threaded adapter built in, rather than a 2" visual back + refractor-type diagonal. An SCT diagonal should be lighter and save some backfocus distance....right? And I think it'd be a more reliable connection if I wind up hanging a binoviewer on the scope.
What about prism diagonal vs mirror for a C8? The good prisms are not cheap but if they reduce scatter a little compared to a dielectric mirror, it might be worth it. Might be a way to effectively buy back some contrast that's given up to the large obstruction. Since the baffle tube limits the clear aperture of the C8 to something less than full 2" format I wonder of a Baader T2 prism with clear aperture of 34mm might be a good value?
What about the Chinese-made Quartz mirror diagonals? I have a WO quartz diagonal with dielectric coatings on my refractor and it's a great unit, doesn't seem to introduce any appreciable scatter or aberration at all. I wonder how the cheaper Chinese quartz diagonals (GSO makes a lot of them I think) compare? Maybe I should just get a WO SCT adapter ring for the diagonal I already have....hmmm...
|
rmollise
Postmaster
Reged: 07/06/07
|
Re: 2" Diagonal for Nexstar 8SE
[Re: MattT]
#5291915 - 06/27/12 05:21 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
An SCT diagonal is fine. So is a refractor diagonal. An SCT model might save you a little backfocus, but not much. I do prefer a refractor style one for EQ mounted scopes since it is easier to adjust the angle of one...but that is about it.
|
Eddgie
Postmaster
Reged: 02/01/06
|
Re: 2" Diagonal for Nexstar 8SE
[Re: MattT]
#5291922 - 06/27/12 05:23 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
You might hear people say that a prism is better than a good mirror for a diagonal, but you won't hear that from me.
I would recommend a good dielectric. Not becase it is better than a good prism, but because it costs less and will resist scratching when cleaning, and cleaning a diagonal when it is dirty is actually quite important.
It will perform as well as a Prism.
Differences in good diagonals, be they enhanced aluminum, dielectric, or prism, are almost impossible to see at the eyepeice.
Of course there will be someone that owns an expensive prism that will say they are better, but having owned many different prism, enhanced aluminum, and dielectrics, I found the differences in optical performance to be to small to see.
Just buy a good quality diagonal and rest assured that it is not going to degrade the image.
|
REC
Carpal Tunnel
Reged: 10/20/10
Loc: NC
|
Re: 2" Diagonal for Nexstar 8SE
[Re: Eddgie]
#5293386 - 06/28/12 02:30 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
For photography, the visual back is more convenient....FYI. I can easily swap out the diagonal with the EP in it and slip in the camera for some quick snap shots of the Moon and planets. Either way, the 2" will give you a little more light to work with vs. the 1.25"
|
Sorny
super member
Reged: 03/15/12
Loc: Southern MN
|
Re: 2" Diagonal for Nexstar 8SE
[Re: REC]
#5293394 - 06/28/12 02:36 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
You may want to consider a Denk Power Switch S1 diagonal (or S2 if you might want to bino view). The shorty version would probably be best for a NexStar 8, but it is a 2" diagonal, Focal reducer, and Barlow in one convenient package. Each eyepiece becomes 3. This is the very definition of slick. I love not having to mess around to get different magnifications. Roughly 5 seconds to go from low-mag to high-mag, including re-focus time... Not cheap, though not that expensive when you consider what it includes, either.
Most nights, I just throw my WO binos in with 20mm eyepieces and use the setup all night. For me, ~83x/~143x/~238x is a near perfect range of magnifications; these values would be different for you in the 8", but would follow a similar progression.
|
mclewis1
Thread Killer
Reged: 02/25/06
Loc: New Brunswick, Canada
|
Re: 2" Diagonal for Nexstar 8SE
[Re: REC]
#5293441 - 06/28/12 03:11 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Either way, the 2" will give you a little more light to work with vs. the 1.25"
"more light" usually means brighter and that isn't the case here. 2" accessories will give you a bit wider fov to work with ... but they won't make anything brighter.
|
MattT
sage
Reged: 04/20/06
Loc: SF Bay Area
|
Re: 2" Diagonal for Nexstar 8SE
[Re: mclewis1]
#5293847 - 06/28/12 07:57 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Thanks for the comments. I've ordered the Nexstar and will try it with 1.25" output until I see how I like it. But the advantages mentioned of the 2" visual back are helpful; I hadn't thought of that.
The Denk Power Switch was something I hadn't thought of, either.....One reason I wanted the Nexstar was for a lightweight large(ish) aperture grab-and-go setup, and being able to do a variety of observing with only 1 or 2 eyepieces would fit in with that plan.
|
|
9 registered and 9 anonymous users are browsing this forum.
Moderator: Cotts, Starman27
Print Thread
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Thread views: 550
|
|
|
|
|
|
|
Previous
Index
Next
Threaded
